Curve of constant width: Difference between revisions

From formulasearchengine
Jump to navigation Jump to search
No edit summary
 
en>AnonMoos
Undid revision 585714274 by 202.65.144.206 (talk)
Line 1: Line 1:
That will help start, all we claim to accomplish is realize a authentic little dinner table in this way which has your [http://Www.Dict.cc/englisch-deutsch/adapted.html adapted] prices, as well as , again I will coming you how to try linear interpolation to make [http://search.about.com/?q=account account] any added cost.<br><br>If you have any inquiries regarding exactly where and how to use [http://circuspartypanama.com hack clash of clans no survey], you can call us at our web-page. But Supercell, by allowing those illusion on the multi-player game, taps into the best instinctual male drive to assist you to from the status hierarchy, and even though it''s unattainable to the surface of your hierarchy if it's not necessary been logging in morning because the game became available plus you invested actually money in extra builders, the drive for obtaining a small bit further forces enough visitors to use up a real income towards virtual 'gems'" that exercise could be the top-grossing app within the App Store.<br><br>Video gaming are very well-liked in a few homes. The associated with people perform online games to pass through time, however, some blessed consumers are paid to experience clash of clans sur pc. Casino is going to automatically be preferred for some your time into the future. These tips will to be able to if you are interested to try out online.<br><br>A marvelous method to please your kids with a gaming device and ensure they survive fit is to buying a Wii. This console needs real task perform. Your children won't be lounging for hours on termination playing clash of clans hack. They need to be moving around as the right way to play the games at this particular system.<br><br>Whether you're looking Conflict of Young couples Jewels Free, or you can find yourself just buying a Steal Conflict of Tribes, right now the smartest choice on the internet, absolutely free as well as only takes a short while to get all many.<br><br>Conserve lots of some money on your personal games, think about signing up into a assistance an individual can rent payments programs from. The reasonable price of these lease legal agreements for the year are normally under the be of two video game. You can preserve the video games titles until you get over them and simply send out them back ever again and purchase another type.<br><br>It's a nice process. Breaking the appraisement bottomward into chunks of time that go about doing faculty to be happy to bodies (hour/day/week) makes who's accessible to visualize. Everybody knows what it seems like to accept to reduce each day. That's additionally actual accessible toward tune. If you change your own apperception after and adjudge that one day should bulk more, all you allegation to try and therefore do is amend 1 benefit.
[[File:Hopf Fibration.png|right|250px|thumb|The Hopf fibration can be visualized using a [[stereographic projection]] of ''S''<sup>3</sup> to '''R'''<sup>3</sup> and then compressing ''R''<sup>3</sup> to a ball. This image shows points on ''S''<sup>2</sup> and their corresponding fibers with the same color.]]
[[Image:Hopfkeyrings.jpg|right|250px|thumb|Pairwise linked [[keyring]]s mimic part of the Hopf fibration.]]
In the mathematical field of [[topology]], the '''Hopf fibration''' (also known as the '''Hopf bundle''' or '''Hopf map''') describes a [[3-sphere]] (a [[hypersphere]] in [[four-dimensional space]]) in terms of [[circles]] and an ordinary [[sphere]]. Discovered by [[Heinz Hopf]] in 1931, it is an influential early example of a [[fiber bundle]]. Technically, Hopf found a many-to-one [[continuous function]] (or "map") from the 3-sphere onto the 2-sphere such that each distinct ''point'' of the 2-sphere comes from a distinct ''circle'' of the 3-sphere {{harv|Hopf|1931}}. Thus the 3-sphere is composed of fibers, where each fiber is a circle — one for each point of the 2-sphere.
 
This fiber bundle structure is denoted
:<math>S^1 \hookrightarrow S^3 \xrightarrow{\ p \, } S^2, </math>
meaning that the fiber space ''S''<sup>1</sup> (a circle) is [[embedding|embedded]] in the total space ''S''<sup>3</sup> (the 3-sphere), and ''p'' :&nbsp;''S''<sup>3</sup> → ''S''<sup>2</sup> (Hopf's map) projects ''S''<sup>3</sup> onto the base space ''S''<sup>2</sup> (the ordinary 2-sphere). The Hopf fibration, like any fiber bundle, has the important property that it is [[locally trivial|locally]] a [[product space]]. However it is not a ''trivial'' fiber bundle, i.e., ''S''<sup>3</sup> is not ''globally'' a product of ''S''<sup>2</sup> and ''S''<sup>1</sup> although locally it is indistinguishable from it.
 
This has many implications: for example the existence of this bundle shows that the higher [[homotopy groups of spheres]] are not trivial in general. It also provides a basic example of a [[principal bundle]], by identifying the fiber with the [[circle group]].
 
[[Stereographic projection]] of the Hopf fibration induces a remarkable structure on '''R'''<sup>3</sup>, in which space is filled with nested [[torus|tori]] made of linking [[Villarceau circles]]. Here each fiber projects to a [[circle]] in space (one of which is a line, thought of as a "circle through infinity"). Each torus is the stereographic projection of the [[inverse image]] of a circle of latitude of the 2-sphere. (Topologically, a torus is the product of two circles.)  These tori are illustrated in the images at right.  When '''R'''<sup>3</sup> is compressed to a ball, some geometric structure is lost although the topological structure is retained (see [[Geometry#Topology_and_geometry|Topology and geometry]]).  The loops are [[homeomorphic]] to circles, although they are not geometric [[circle]]s.
 
There are numerous generalizations of the Hopf fibration. The unit sphere in [[complex coordinate space]] '''C'''<sup>''n''+1</sup> fibers naturally over the [[complex projective space]] '''CP'''<sup>''n''</sup> with circles as fibers, and there are also [[real number|real]], [[quaternion]]ic, and [[octonion]]ic versions of these fibrations. In particular, the Hopf fibration belongs to a family of four fiber bundles in which the total space, base space, and fiber space are all spheres:
:<math>S^0\hookrightarrow S^1 \to S^1,</math>
:<math>S^1\hookrightarrow S^3 \to S^2,</math>
:<math>S^3\hookrightarrow S^7 \to S^4,</math>
:<math>S^7\hookrightarrow S^{15}\to S^8.</math>
By [[Adams' theorem]] such fibrations can occur only in these dimensions.
 
The Hopf fibration is important in [[twistor theory]].
 
==Definition and construction==
 
For any [[natural number]] ''n'', an ''n''-dimensional sphere, or [[n-sphere]], can be defined as the set of points in an (''n''+1)-dimensional [[Euclidean space|space]] which are a fixed distance from a central [[point (mathematics)|point]]. For concreteness, the central point can be taken to be the [[origin (mathematics)|origin]], and the distance of the points on the sphere from this origin can be assumed to be a unit length. With this convention, the ''n''-sphere, ''S''<sup>''n''</sup>, consists of the points (''x''<sub>1</sub>,&nbsp;''x''<sub>2</sub>,&nbsp;…,&nbsp;''x''<sub>''n''+1</sub>) in '''R'''<sup>''n''+1</sup> with ''x''<sub>1</sub><sup>2</sup>&nbsp;+&nbsp;''x''<sub>2</sub><sup>2</sup>&nbsp;+&nbsp;⋯+&nbsp;''x''<sub>''n''+1</sub><sup>2</sup>&nbsp;=&nbsp;1. For example, the 3-sphere consists of the points (''x''<sub>1</sub>,&nbsp;''x''<sub>2</sub>,&nbsp;''x''<sub>3</sub>,&nbsp;''x''<sub>4</sub>) in '''R'''<sup>4</sup> with ''x''<sub>1</sub><sup>2</sup>&nbsp;+&nbsp;''x''<sub>2</sub><sup>2</sup>&nbsp;+&nbsp;''x''<sub>3</sub><sup>2</sup>&nbsp;+&nbsp;''x''<sub>4</sub><sup>2</sup>&nbsp;=&nbsp;1.
 
The Hopf fibration ''p'': ''S''<sup>3</sup> → ''S''<sup>2</sup> of the 3-sphere over the 2-sphere can be defined in several ways.
 
===Direct construction===
 
Identify '''R'''<sup>4</sup>  with '''C'''<sup>2</sup> and '''R'''<sup>3</sup> with '''C'''×'''R''' (where '''C''' denotes the [[complex number]]s) by writing:
:(''x''<sub>1</sub>,&nbsp;''x''<sub>2</sub>,&nbsp;''x''<sub>3</sub>,&nbsp;''x''<sub>4</sub>)  as  (''z''<sub>0</sub>&nbsp;= ''x''<sub>1</sub>&nbsp;+&nbsp;i''x''<sub>2</sub>,&nbsp;''z''<sub>1</sub>&nbsp;= ''x''<sub>3</sub>&nbsp;+&nbsp;i''x''<sub>4</sub>);  and
:(''x''<sub>1</sub>,&nbsp;''x''<sub>2</sub>,&nbsp;''x''<sub>3</sub>) as (''z''&nbsp;= ''x''<sub>1</sub>&nbsp;+&nbsp;i''x''<sub>2</sub>,&nbsp;''x''&nbsp;= ''x''<sub>3</sub>).
Thus ''S''<sup>3</sup> is identified with the [[subset]] of all (''z''<sub>0</sub>, ''z''<sub>1</sub>) in '''C'''<sup>2</sup> such that |''z''<sub>0</sub>|<sup>2</sup> + |''z''<sub>1</sub>|<sup>2</sup>&nbsp;= 1, and ''S''<sup>2</sup> is identified with the subset of all (''z'', ''x'') in '''C'''×'''R''' such that |''z''|<sup>2</sup>&nbsp;+&nbsp;''x''<sup>2</sup> = 1. (Here, for a complex number ''z''&nbsp;= ''x''&nbsp;+&nbsp;i''y'', |''z''|<sup>2</sup>&nbsp;= ''z''&nbsp;''z''<sup>∗</sup>&nbsp;= ''x''<sup>2</sup>&nbsp;+&nbsp;''y''<sup>2</sup>, where the star denotes the [[complex conjugate]].) Then the Hopf fibration ''p'' is defined by
:''p''(''z''<sub>0</sub>, ''z''<sub>1</sub>) = (2''z''<sub>0</sub>''z''<sub>1</sub><sup>&lowast;</sup>, |''z''<sub>0</sub>|<sup>2</sup>&nbsp;−&nbsp;|''z''<sub>1</sub>|<sup>2</sup>).
 
The first component is a complex number, whereas the second component is real.  Any point on the 3-sphere must have  the property that |''z''<sub>0</sub>|<sup>2</sup>&nbsp;+&nbsp;|''z''<sub>1</sub>|<sup>2</sup>&nbsp;= 1. If that is so, then ''p''(''z''<sub>0</sub>, ''z''<sub>1</sub>) lies on the unit 2-sphere in '''C'''×'''R''', as may be shown by squaring the complex and real components of ''p''
 
:<math>2 z_{0} z_{1}^{\ast} \cdot 2 z_{0}^{\ast} z_{1} +
\left( \left| z_{0} \right|^{2} - \left| z_{1} \right|^{2} \right)^{2} =
4 \left| z_{0} \right|^{2} \left| z_{1} \right|^{2} +
\left| z_{0} \right|^{4} - 2 \left| z_{0} \right|^{2} \left| z_{1} \right|^{2} + \left| z_{1} \right|^{4} =
\left( \left| z_{0} \right|^{2} + \left| z_{1} \right|^{2} \right)^{2} = 1</math>
 
Furthermore, if two points on the 3-sphere map to the same point on the 2-sphere, i.e., if ''p''(''z''<sub>0</sub>, ''z''<sub>1</sub>) = ''p''(''w''<sub>0</sub>, ''w''<sub>1</sub>), then (''w''<sub>0</sub>, ''w''<sub>1</sub>) must equal (''λ''&nbsp;''z''<sub>0</sub>, ''λ''&nbsp;''z''<sub>1</sub>) for some complex number ''λ'' with |''λ''|<sup>2</sup>&nbsp;=&nbsp;1.  The converse is also true; any two points on the 3-sphere that differ by a common complex factor ''λ'' map to the same point on the 2-sphere.  These conclusions follow, because the complex factor ''λ'' cancels with its complex conjugate ''λ''<sup>∗</sup> in both parts of ''p'': in the complex 2''z''<sub>0</sub>''z''<sub>1</sub><sup>∗</sup> component and in the real component |''z''<sub>0</sub>|<sup>2</sup>&nbsp;−&nbsp;|''z''<sub>1</sub>|<sup>2</sup>.
 
Since the set of complex numbers ''λ'' with |''λ''|<sup>2</sup>&nbsp;=&nbsp;1 form the unit circle in the complex plane, it follows that for each point ''m'' in ''S''<sup>2</sup>, the [[inverse image]] ''p''<sup>−1</sup>(''m'') is a circle, i.e., ''p''<sup>−1</sup>''m''&nbsp;≅&nbsp;''S''<sup>1</sup>. Thus the 3-sphere is realized as a [[disjoint union]] of these circular fibers.
 
====Geometric interpretation using the complex projective line====
 
A geometric interpretation of the fibration may be obtained using the [[complex projective line]], '''CP'''<sup>1</sup>, which is defined to be the set of all complex one dimensional [[vector subspace|subspaces]] of '''C'''<sup>2</sup>. Equivalently, '''CP'''<sup>1</sup> is the [[quotient space|quotient]] of '''C'''<sup>2</sup>\{0} by the [[equivalence relation]] which identifies (''z''<sub>0</sub>, ''z''<sub>1</sub>) with (''λ''&nbsp;''z''<sub>0</sub>, ''λ''&nbsp;''z''<sub>1</sub>) for any nonzero complex number ''λ''. On any complex line in '''C'''<sup>2</sup> there is a circle of unit norm, and so the restriction of the [[quotient map]] to the points of unit norm is a fibration of ''S''<sup>3</sup> over '''CP'''<sup>1</sup>.
 
'''CP'''<sup>1</sup> is diffeomorphic to a 2-sphere: indeed it can be identified with the [[Riemann sphere]] '''C'''<sub>∞</sub> = '''C''' ∪ {∞}, which is the [[one point compactification]] of '''C''' (obtained by adding a [[point at infinity]]). The formula given for ''p'' above defines an explicit diffeomorphism between the complex projective line and the ordinary 2-sphere in 3-dimensional space. Alternatively, the point (''z''<sub>0</sub>, ''z''<sub>1</sub>) can be mapped to the ratio ''z''<sub>1</sub>/''z''<sub>0</sub> in the Riemann sphere '''C'''<sub>∞</sub>.
 
====Fiber bundle structure====
 
The Hopf fibration defines a [[fiber bundle]], with bundle projection ''p''. This means that it has a  "local product structure", in the sense that every point of the 2-sphere has some [[neighborhood (topology)|neighborhood]] ''U'' whose inverse image in the 3-sphere can be [[homeomorphism|identified]] with the [[product space|product]] of ''U'' and a circle: ''p''<sup>−1</sup>(''U'')&nbsp;≅&nbsp;''U''×''S''<sup>1</sup>. Such a fibration is said to be [[locally trivial]].
 
For the Hopf fibration, it is enough to remove a single point ''m'' from ''S''<sup>2</sup> and the corresponding circle ''p''<sup>−1</sup>(''m'') from ''S''<sup>3</sup>; thus one can take ''U'' = ''S''<sup>2</sup>\{''m''}, and any point in ''S''<sup>2</sup> has a neighborhood of this form.
 
===Geometric interpretation using rotations===
 
Another geometric interpretation of the Hopf fibration can be obtained by considering rotations of the 2-sphere in ordinary 3-dimensional space. The [[rotation group SO(3)]] has a [[Double covering group|double cover]], the [[spin group]] Spin(3), [[diffeomorphic]] to the 3-sphere. The spin group acts [[transitive group action|transitively]] on ''S''<sup>2</sup> by rotations. The [[Group action#Orbits and stabilizers|stabilizer]] of a point is isomorphic to the [[circle group]]. It follows easily that the 3-sphere is a [[principal circle bundle]] over the 2-sphere, and this is the Hopf fibration.
 
To make this more explicit, there are two approaches: the group Spin(3) can either be identified with the group [[Symplectic group#Sp(n)|Sp(1)]] of unit [[quaternion]]s, or with the [[special unitary group]] [[SU(2)]].
 
In the first approach, a vector (''x''<sub>1</sub>, ''x''<sub>2</sub>, ''x''<sub>3</sub>, ''x''<sub>4</sub>) in '''R'''<sup>4</sup> is interpreted as a quaternion ''q'' ∈ '''H''' by writing
:<math> q = x_1+\bold{i}x_2+\bold{j}x_3+\bold{k}x_4.\,\!</math>
The 3-sphere is then identified with the quaternions of unit norm, i.e., those ''q'' ∈ '''H''' for which |''q''|<sup>2</sup> = 1, where |''q''|<sup>2</sup> = ''q q''<sup>∗</sup>, which is equal to ''x''<sub>1</sub><sup>2</sup> + ''x''<sub>2</sub><sup>2</sup> + ''x''<sub>3</sub><sup>2</sup> + ''x''<sub>4</sub><sup>2</sup> for ''q'' as above.
 
On the other hand, a vector (''y''<sub>1</sub>, ''y''<sub>2</sub>, ''y''<sub>3</sub>) in '''R'''<sup>3</sup> can be interpreted as an imaginary quaternion
:<math> p = \bold{i}y_1+\bold{j}y_2+\bold{k}y_3. \,\!</math>
Then, as is well-known since {{Harvtxt|Cayley|1845}}, the mapping
:<math> p \mapsto q p q^* \,\!</math>
is a rotation in '''R'''<sup>3</sup>: indeed it is clearly an [[isometry]], since |''q p q''<sup>∗</sup>|<sup>2</sup> = ''q p q''<sup>∗</sup> ''q p''<sup>∗</sup> ''q''<sup>∗</sup> = ''q p p''<sup>∗</sup> ''q''<sup>∗</sup> = |''p''|<sup>2</sup>, and it is not hard to check that it preserves orientation.
 
In fact, this identifies the group of [[unit quaternion]]s with the group of rotations of '''R'''<sup>3</sup>, modulo the fact that the unit quaternions ''q'' and −''q'' determine the same rotation. As noted above, the rotations act transitively on ''S''<sup>2</sup>, and the set of unit quaternions ''q'' which fix a given unit imaginary quaternion ''p'' have the form ''q'' = ''u'' + ''v'' ''p'', where ''u'' and ''v'' are real numbers with ''u''<sup>2</sup> + ''v''<sup>2</sup> = 1. This is a circle subgroup. For concreteness, one can take ''p'' = '''k''', and then the Hopf fibration can be defined as the map sending a unit quaternion ω to ω '''k''' ω<sup>∗</sup>. All the quaternions ω''q'', where ''q'' is one of the circle of unit quaternions that fix ''k'', get mapped to the same thing (which happens to be one of the two 180° rotations rotating ''k'' to the same place as ω does).
 
Another way to look at this fibration is that every unit quaternion ω moves the plane spanned by {1, ''k''} to a new plane spanned by {ω, ω''k''}. Any quaternion ω''q'', where ''q'' is one of the circle of unit quaternions that fix ''k'', will have the same effect. We put all these into one fibre, and the fibres can be mapped one-to-one to the 2-sphere of 180° rotations which is the range of ω''k''ω<sup>*</sup>.
 
This approach is related to the direct construction by identifying a quaternion ''q'' = ''x''<sub>1</sub> + '''i''' ''x''<sub>2</sub> + '''j''' ''x''<sub>3</sub> + '''k''' ''x''<sub>4</sub> with the 2×2 matrix:
:<math>\begin{bmatrix} x_1+\bold i x_2 & x_3+\bold i x_4 \\ -x_3+\bold i x_4 & x_1-\bold i x_2 \end{bmatrix}.\,\!</math>
This identifies the group of unit quaternions with SU(2), and the imaginary quaternions with the skew-hermitian 2×2 matrices (isomorphic to '''C'''×'''R''').
 
====Explicit formulae====
 
The rotation induced by a unit quaternion ''q'' = ''w'' + '''i''' ''x'' + '''j''' ''y'' + '''k''' ''z'' is given explicitly by the [[orthogonal matrix]]
:<math>\begin{bmatrix}
1-2(y^2+z^2) & 2(xy - wz) & 2(xz+wy)\\
2(xy + wz) & 1-2(x^2+z^2) & 2(yz-wx)\\
2(xz-wy) & 2(yz+wx) & 1-2(x^2+y^2)
\end{bmatrix} . </math>
Here we find an explicit real formula for the bundle projection. For, the fixed unit vector along the ''z'' axis, (0,0,1), rotates to another unit vector,
:<math> \Big(2(xz+wy) , 2(yz-wx) , 1-2(x^2+y^2)\Big) , \,\!</math>
which is a continuous function of (''w'',''x'',''y'',''z''). That is, the image of ''q'' is where it aims the ''z'' axis. The fiber for a given point on ''S''<sup>2</sup> consists of all those unit quaternions that aim there.
 
To write an explicit formula for the fiber over a point (''a'',''b'',''c'') in ''S''<sup>2</sup>, we may proceed as follows. Multiplication of unit quaternions produces composition of rotations, and
:<math>q_{\theta} = \cos \theta + \bold{k} \sin \theta</math>
is a rotation by 2θ around the ''z'' axis. As θ varies, this sweeps out a [[great circle]] of ''S''<sup>3</sup>, our prototypical fiber. So long as the base point, (''a'',''b'',''c''), is not the antipode, (0,0,−1), the quaternion
:<math> q_{(a,b,c)} = \frac{1}{\sqrt{2(1+c)}}(1+c-\bold{i}b+\bold{j}a) </math>
will aim there. Thus the fiber of (''a'',''b'',''c'') is given by quaternions of the form ''q''<sub>(''a'',''b'',''c'')</sub>''q''<sub>θ</sub>, which are the ''S''<sup>3</sup> points
:<math> \frac{1}{\sqrt{2(1+c)}}
  \Big((1+c) \cos (\theta ),
  a \sin (\theta )-b \cos (\theta ),
  a \cos (\theta )+b \sin (\theta ),
  (1+c) \sin (\theta )\Big) . \,\!</math>
Since multiplication by ''q''<sub>(''a'',''b'',''c'')</sub> acts as a rotation of quaternion space, the fiber is not merely a topological circle, it is a geometric circle. The final fiber, for (0,0,−1), can be given by using ''q''<sub>(0,0,−1)</sub>&nbsp;= '''i''', producing
:<math> \Big(0,\cos (\theta ),-\sin (\theta ),0\Big),</math>
which completes the bundle.
 
Thus, a simple way of visualizing the Hopf fibration is as follows.  Any point on the 3-sphere is equivalent to a [[quaternion]], which in turn is equivalent to a particular rotation of a [[Cartesian coordinate system|Cartesian coordinate frame]] in three dimensions.  The set of all possible quaternions produces the set of all possible rotations, which moves the tip of one unit vector of such a coordinate frame (say, the '''z''' vector) to all possible points on a unit 2-sphere.  However, fixing the tip of the '''z''' vector does not specify the rotation fully; a further rotation is possible about the '''z'''-axis.  Thus, the 3-sphere is mapped onto the 2-sphere, plus a single rotation.
 
===Fluid Mechanics===
If the Hopf fibration is treated as a vector field in 3 dimensional space then there is a solution to the (compressible, non-viscous) [[Navier-Stokes equations]] of fluid dynamics in which the fluid flows along the circles of the projection of the Hopf fibration in 3 dimensional space. The size of the velocities, the density and the pressure can be chosen at each point to satisfy the equations. All these quantities fall to zero going away from the centre. If a is the distance to the inner ring, the velocities, pressure and density fields are given by:
:<math>\mathbf{v}(x,y,z) = A \left(a^2+x^2+y^2+z^2\right)^{-2} \left( 2(-ay+xz), 2(ax+yz) , a^2-x^2-y^2+z^2 \right)</math>
:<math>p(x,y,z) = -A^2B \left(a^2+x^2+y^2+z^2\right)^{-3},</math>
:<math>\rho(x,y,z) = 3B\left(a^2+x^2+y^2+z^2\right)^{-1}</math>
for arbitrary constants A and B. Similar patterns of fields are found as [[soliton]] solutions of [[magnetohydrodynamics]]:<ref>{{citation
| url= http://www.jetp.ac.ru/cgi-bin/dn/e_055_01_0069.pdf
| year=1982
| title=Topological solitons in magnetohydrodynamics
| first=A. M
| last= Kamchatno
}}</ref>
 
==Generalizations==
 
The Hopf construction, viewed as a fiber bundle ''p'': ''S''<sup>3</sup> → '''CP'''<sup>''1''</sup>, admits several generalizations, which are also often known as Hopf fibrations. First, one can replace the projective line by an ''n''-dimensional [[projective space]]. Second, one can replace the complex numbers by any (real) [[division algebra]], including (for ''n'' = 1) the [[octonion]]s.
 
===Real Hopf fibrations===
 
A real version of the Hopf fibration is obtained by regarding the circle ''S''<sup>1</sup> as a subset of '''R'''<sup>2</sup> in the usual way and by
idenitifying antipodal points. This gives a fiber bundle ''S''<sup>1</sup> → '''RP'''<sup>1</sup>  over the [[real projective line]] with fiber ''S''<sup>0</sup> = {1, -1}. Just as '''CP'''<sup>1</sup> is diffeomorphic to a sphere, '''RP'''<sup>1</sup> is diffeomorphic to a circle.
 
More generally, the ''n''-sphere ''S''<sup>''n''</sup> fibers over [[real projective space]] '''RP'''<sup>''n''</sup> with fiber ''S''<sup>0</sup>.
 
===Complex Hopf fibrations===
 
The Hopf construction gives circle bundles ''p'' : ''S''<sup>2''n''+1</sup> → '''CP'''<sup>''n''</sup> over [[complex projective space]]. This is actually the restriction of the [[tautological line bundle]] over '''CP'''<sup>''n''</sup> to the unit sphere in '''C'''<sup>''n''+1</sup>.
 
===Quaternionic Hopf fibrations===
 
Similarly, one can regard ''S''<sup>4''n+3''</sup> as lying in '''H'''<sup>''n+1''</sup> ([[quaternion]]ic ''n''-space) and factor out by unit quaternion (= ''S''<sup>3</sup>) multiplication to get '''HP'''<sup>''n''</sup>.  In particular, since ''S''<sup>4</sup> = '''HP'''<sup>1</sup>, there is a bundle ''S''<sup>7</sup> → ''S''<sup>4</sup> with fiber ''S''<sup>3</sup>.
 
===Octonionic Hopf fibrations===
 
A similar construction with the [[octonion]]s yields a bundle ''S''<sup>15</sup> → ''S''<sup>8</sup> with fiber ''S''<sup>7</sup>. But the sphere ''S''<sup>31</sup> does not fiber over ''S''<sup>16</sup> with fiber ''S''<sup>15</sup>. One can regard ''S''<sup>8</sup> as the [[octonionic projective line]] '''OP'''<sup>1</sup>. Although one can also define an [[Cayley plane|octonionic projective plane]] '''OP'''<sup>2</sup>, the sphere ''S''<sup>23</sup> does not fiber over '''OP'''<sup>2</sup>
with fiber ''S''<sup>7</sup>.<ref>{{cite book | title=Manifolds all of whose Geodesics are Closed | last=Besse | first=Arthur | authorlink=Arthur Besse | year=1978 | publisher=Springer-Verlag | isbn=978-3-540-08158-6 }} (§0.26 on page 6)</ref><ref>[http://groups.google.com/group/sci.math.research/browse_thread/thread/3e4152e24122022c/ sci.math.research 1993 thread "Spheres fibred by spheres"]</ref>
 
===Fibrations between spheres===
 
Sometimes the term "Hopf fibration" is restricted to the fibrations between spheres obtained above, which are
* ''S''<sup>1</sup> → ''S''<sup>1</sup> with fiber ''S''<sup>0</sup>
* ''S''<sup>3</sup> → ''S''<sup>2</sup> with fiber ''S''<sup>1</sup>
* ''S''<sup>7</sup> → ''S''<sup>4</sup> with fiber ''S''<sup>3</sup>
* ''S''<sup>15</sup> → ''S''<sup>8</sup> with fiber ''S''<sup>7</sup>
As a consequence of [[Adams' theorem]], fiber bundles with [[sphere]]s as total space, base space, and fiber can occur only in these dimensions.
Fiber bundles with similar properties, but different from the Hopf fibrations, were used by [[John Milnor]] to construct [[exotic sphere]]s.
 
==Geometry and applications==
[[Image:Villarceau circles.gif|thumb|right|The fibers of the Hopf fibration stereographically project to a family of [[Villarceau circles]] in '''R'''<sup>3</sup>.]]
The Hopf fibration has many implications, some purely attractive, others deeper. For example, [[stereographic projection]] ''S''<sup>3</sup> → '''R'''<sup>3</sup> induces a remarkable structure in '''R'''<sup>3</sup>, which in turn illuminates the topology of the bundle {{Harv|Lyons|2003}}. Stereographic projection preserves circles and maps the Hopf fibers to geometrically perfect circles in '''R'''<sup>3</sup> which fill space. Here there is one exception: the Hopf circle containing the projection point maps to a straight line in '''R'''<sup>3</sup> &mdash; a "circle through infinity".
 
The fibers over a circle of latitude on ''S''<sup>2</sup> form a [[torus]] in ''S''<sup>3</sup> (topologically, a torus is the product of two circles) and these project to nested [[torus]]es in '''R'''<sup>3</sup> which also fill space. The individual fibers map to linking [[Villarceau circles]] on these tori, with the exception of the circle through the projection point and the one through its [[antipodal point|opposite point]]: the former maps to a straight line, the latter to a unit circle perpendicular to, and centered on, this line, which may be viewed as a degenerate torus whose radius has shrunken to zero. Every other fiber image encircles the line as well, and so, by symmetry, each circle is linked through ''every'' circle, both in '''R'''<sup>3</sup> and in ''S''<sup>3</sup>. Two such linking circles form a [[Hopf link]] in '''R'''<sup>3</sup>
 
Hopf proved that the Hopf map has [[Hopf invariant]] 1, and therefore is not [[null-homotopic]]. In fact it generates the [[homotopy group]] π<sub>3</sub>(''S''<sup>2</sup>) and has infinite order.
 
In [[quantum mechanics]], the Riemann sphere is known as the [[Bloch sphere]], and the Hopf fibration describes the topological structure of a quantum mechanical [[two-level system]] or [[qubit]]. Similarly, the topology of a pair of entangled two-level systems is given by the Hopf fibration
:<math>S^3 \hookrightarrow S^7\to S^4.</math>
{{harv|Mosseri|Dandoloff|2001}}.
 
==Discrete examples==
[[File:120-cell_rings.jpg|thumb|Two rings of 10 dodecahedra of the [[120-cell]]]]
{{Unreferenced section|date=July 2013}}
Three of the six [[Convex regular 4-polytope|regular 4-polytopes]] – 8-cell ([[tesseract]]), [[24-cell]], and [[120-cell]] – can each be partitioned into disjoint great circle (regular polygon) rings of cells forming discrete Hopf fibrations of these polytopes.  The tesseract partitions into two interlocking rings of four cubes each.  The 24-cell partitions into four rings of six [[octahedron]]s each.  The 120-cell partitions<ref name="goodfib">{{cite web|last=Goucher|first=AP|title=Good fibrations|url=http://cp4space.wordpress.com/2012/09/27/good-fibrations/}}</ref>  into [[120-cell#Intertwining_rings|twelve rings]] of ten [[dodecahedron|dodecahedra]] each.  The 24-cell also contains a fibration of six rings of four octahedrons each stacked end to end at their vertices.
 
The [[600-cell]] partitions into 20 rings of 30 [[tetrahedron|tetrahedra]] each in a very interesting, quasi-periodic chain called the [[Boerdijk–Coxeter helix]].  When superimposed onto the 3-sphere curvature it becomes periodic with a period of 10 vertices, encompassing all 30 cells.  In addition, the [[16-cell]] partitions into two 8-tetrahedron chains, four edges long, and the [[5-cell]] partitions into a single degenerate 5-tetrahedron chain.
 
The above fibrations all map to the following specific tilings of the 2-sphere.<ref name="goodfib"/>
{| class="wikitable"
|-
! S3
! S2
! # of rings
 
! # of cells per ring
! Cell Stacking
|- BGCOLOR="#e0e0ff"
| [[600-cell]] {3,3,5}
| [[Icosahedron]] {3,5}
| style="text-align: center" | 20
| style="text-align: center" | 30
| Boerdijk–Coxeter helix
|- BGCOLOR="#ffe0e0"
| [[120-cell]] {5,3,3}
| [[Dodecahedron]] {5,3}
| style="text-align: center" | 12
| style="text-align: center" | 10
| face stacking
|- BGCOLOR="#ffe0e0"
| rowspan="2" | [[24-cell]]  {3,4,3}
| [[Tetrahedron]]  {3,3}
| style="text-align: center" | 4
| style="text-align: center" | 6
| face stacking
|- BGCOLOR="#e0ffe0"
| [[Cube]]  {4,3}
| style="text-align: center" | 6
| style="text-align: center" | 4
| vertex stacking
|- BGCOLOR="#e0e0ff"
| [[16-cell]]  {3,3,4}
| [[Dihedron]] {n,2}
| style="text-align: center" | 2
| style="text-align: center" | 8
| Boerdijk–Coxeter helix
|- BGCOLOR="#ffe0e0"
| [[8-cell]]  {4,3,3}
| [[Dihedron]] {n,2}
| style="text-align: center" | 2
| style="text-align: center" | 4
| face stacking
|- BGCOLOR="#e0e0ff"
| [[5-cell]]  {3,3,3}
| Whole 2-[[sphere]]
| style="text-align: center" | 1
| style="text-align: center" | 5
| Boerdijk–Coxeter helix
|}
 
==References==
 
<references />
* {{citation
  | last=Cayley
  | first=Arthur
  | author-link=Arthur Cayley
  | title=On certain results relating to quaternions
  | journal=[[Philosophical Magazine]]
  | volume=26
  | pages=141–145
  | year=1845
  | url=http://www.archive.org/details/collmathpapers01caylrich
}}; reprinted as article 20 in {{citation
| last=Cayley
| first=Arthur
| author-link=Arthur Cayley
| year=1889
| title=The collected mathematical papers of Arthur Cayley
| publisher=[[Cambridge University Press]]
| volume=(1841–1853)
| pages=123–126
| series=I
| isbn=<!-- none given -->
| url=http://www.hti.umich.edu/cgi/t/text/pageviewer-idx?c=umhistmath;cc=umhistmath;rgn=full%20text;idno=ABS3153.0001.001;didno=ABS3153.0001.001;view=image;seq=00000140
}}
* {{citation
  | last=Hopf
  | first=Heinz
  | author-link=Heinz Hopf
  | title=Über die Abbildungen der dreidimensionalen Sphäre auf die Kugelfläche
  | journal=[[Mathematische Annalen]]
  | publisher = [[Springer Science+Business Media|Springer]]
  | location=Berlin
  | volume=104
  | issue=1
  | pages=637–665
  | year=1931
  | issn=0025-5831
  | url=http://www.digizeitschriften.de/index.php?id=loader&tx_jkDigiTools_pi1%5BIDDOC%5D=363429&L=2
  | doi=10.1007/BF01457962
}}
* {{citation
  | last=Hopf
  | first=Heinz
  | author-link=Heinz Hopf
  | title=Über die Abbildungen von Sphären auf Sphären niedrigerer Dimension
  | journal=[[Fundamenta Mathematicae]]
  | publisher=Polish Acad. Sci.
  | location=Warsaw
  | volume=25
  | pages=427–440
  | year=1935
  | issn=0016-2736
}}
* {{citation
  | doi=10.2307/3219300
  | last=Lyons
  | first=David W.
  | title=An Elementary Introduction to the Hopf Fibration
  | journal=[[Mathematics Magazine]]
  | volume=76
  | issue=2
  | pages=87–98
  |date=April 2003
  | url=http://csunix1.lvc.edu/~lyons/pubs/hopf_paper_preprint.pdf
  | format =[[PDF]]
  | issn=0025-570X
  | jstor=3219300
}}
*{{citation
| last1 = Mosseri | first1 = R.
| last2 = Dandoloff | first2 = R.
| title = Geometry of entangled states, Bloch spheres and Hopf fibrations
| journal = J. Phys. A: Math. Gen.
| volume = 34
| issue = 47 | pages = 10243–10252 | year = 2001 | doi = 10.1088/0305-4470/34/47/324
| arxiv = quant-ph/0108137 }}.
* {{citation
  | last=Steenrod
  | first=Norman
  | title=The Topology of Fibre Bundles
  | publisher=[[Princeton University Press]]
  | year=1951
  | publication-date=1999
  | series=PMS <!--
  | number=-->14
  | isbn=978-0-691-00548-5
  | url=http://books.google.com/?id=m_wrjoweDTgC&printsec=frontcover&dq=%22The+Topology+of+Fibre+Bundles%22
}}
*{{citation
| last1 = Urbantke | first1 = H.K.
| title = The Hopf fibration-seven times in physics
| journal = Journal of Geometry and Physics
| volume = 46 | issue = 2 | pages = 125–150 | year = 2003 | doi = 10.1016/S0393-0440(02)00121-3}}.
 
==External links==
*[http://dimensions-math.org/Dim_reg_AM.htm Dimensions Math] Chapters 7  and 8 illustrate the Hopf fibration with animated computer graphics.
* [http://www.youtube.com/watch?v=MFXRRW9goTs/ YouTube animation of the construction of the 120-cell]  By Gian Marco Todesco shows the Hopf fibration of the 120-cell.
* [http://page.math.tu-berlin.de/~gunn/Movies/600cell.mp4 Video of one 30-cell ring of the 600-cell] from http://page.math.tu-berlin.de/~gunn/.
 
[[Category:Algebraic topology]]
[[Category:Geometric topology]]
[[Category:Differential geometry]]
[[Category:Fiber bundles]]
[[Category:Homotopy theory]]

Revision as of 12:59, 12 December 2013

The Hopf fibration can be visualized using a stereographic projection of S3 to R3 and then compressing R3 to a ball. This image shows points on S2 and their corresponding fibers with the same color.
Pairwise linked keyrings mimic part of the Hopf fibration.

In the mathematical field of topology, the Hopf fibration (also known as the Hopf bundle or Hopf map) describes a 3-sphere (a hypersphere in four-dimensional space) in terms of circles and an ordinary sphere. Discovered by Heinz Hopf in 1931, it is an influential early example of a fiber bundle. Technically, Hopf found a many-to-one continuous function (or "map") from the 3-sphere onto the 2-sphere such that each distinct point of the 2-sphere comes from a distinct circle of the 3-sphere Template:Harv. Thus the 3-sphere is composed of fibers, where each fiber is a circle — one for each point of the 2-sphere.

This fiber bundle structure is denoted

meaning that the fiber space S1 (a circle) is embedded in the total space S3 (the 3-sphere), and p : S3S2 (Hopf's map) projects S3 onto the base space S2 (the ordinary 2-sphere). The Hopf fibration, like any fiber bundle, has the important property that it is locally a product space. However it is not a trivial fiber bundle, i.e., S3 is not globally a product of S2 and S1 although locally it is indistinguishable from it.

This has many implications: for example the existence of this bundle shows that the higher homotopy groups of spheres are not trivial in general. It also provides a basic example of a principal bundle, by identifying the fiber with the circle group.

Stereographic projection of the Hopf fibration induces a remarkable structure on R3, in which space is filled with nested tori made of linking Villarceau circles. Here each fiber projects to a circle in space (one of which is a line, thought of as a "circle through infinity"). Each torus is the stereographic projection of the inverse image of a circle of latitude of the 2-sphere. (Topologically, a torus is the product of two circles.) These tori are illustrated in the images at right. When R3 is compressed to a ball, some geometric structure is lost although the topological structure is retained (see Topology and geometry). The loops are homeomorphic to circles, although they are not geometric circles.

There are numerous generalizations of the Hopf fibration. The unit sphere in complex coordinate space Cn+1 fibers naturally over the complex projective space CPn with circles as fibers, and there are also real, quaternionic, and octonionic versions of these fibrations. In particular, the Hopf fibration belongs to a family of four fiber bundles in which the total space, base space, and fiber space are all spheres:

By Adams' theorem such fibrations can occur only in these dimensions.

The Hopf fibration is important in twistor theory.

Definition and construction

For any natural number n, an n-dimensional sphere, or n-sphere, can be defined as the set of points in an (n+1)-dimensional space which are a fixed distance from a central point. For concreteness, the central point can be taken to be the origin, and the distance of the points on the sphere from this origin can be assumed to be a unit length. With this convention, the n-sphere, Sn, consists of the points (x1x2, …, xn+1) in Rn+1 with x12 + x22 + ⋯+ xn+12 = 1. For example, the 3-sphere consists of the points (x1x2x3x4) in R4 with x12 + x22 + x32 + x42 = 1.

The Hopf fibration p: S3S2 of the 3-sphere over the 2-sphere can be defined in several ways.

Direct construction

Identify R4 with C2 and R3 with C×R (where C denotes the complex numbers) by writing:

(x1x2x3x4) as (z0 = x1 + ix2z1 = x3 + ix4); and
(x1x2x3) as (z = x1 + ix2x = x3).

Thus S3 is identified with the subset of all (z0, z1) in C2 such that |z0|2 + |z1|2 = 1, and S2 is identified with the subset of all (z, x) in C×R such that |z|2 + x2 = 1. (Here, for a complex number z = x + iy, |z|2 = z z = x2 + y2, where the star denotes the complex conjugate.) Then the Hopf fibration p is defined by

p(z0, z1) = (2z0z1, |z0|2 − |z1|2).

The first component is a complex number, whereas the second component is real. Any point on the 3-sphere must have the property that |z0|2 + |z1|2 = 1. If that is so, then p(z0, z1) lies on the unit 2-sphere in C×R, as may be shown by squaring the complex and real components of p

Furthermore, if two points on the 3-sphere map to the same point on the 2-sphere, i.e., if p(z0, z1) = p(w0, w1), then (w0, w1) must equal (λ z0, λ z1) for some complex number λ with |λ|2 = 1. The converse is also true; any two points on the 3-sphere that differ by a common complex factor λ map to the same point on the 2-sphere. These conclusions follow, because the complex factor λ cancels with its complex conjugate λ in both parts of p: in the complex 2z0z1 component and in the real component |z0|2 − |z1|2.

Since the set of complex numbers λ with |λ|2 = 1 form the unit circle in the complex plane, it follows that for each point m in S2, the inverse image p−1(m) is a circle, i.e., p−1m ≅ S1. Thus the 3-sphere is realized as a disjoint union of these circular fibers.

Geometric interpretation using the complex projective line

A geometric interpretation of the fibration may be obtained using the complex projective line, CP1, which is defined to be the set of all complex one dimensional subspaces of C2. Equivalently, CP1 is the quotient of C2\{0} by the equivalence relation which identifies (z0, z1) with (λ z0, λ z1) for any nonzero complex number λ. On any complex line in C2 there is a circle of unit norm, and so the restriction of the quotient map to the points of unit norm is a fibration of S3 over CP1.

CP1 is diffeomorphic to a 2-sphere: indeed it can be identified with the Riemann sphere C = C ∪ {∞}, which is the one point compactification of C (obtained by adding a point at infinity). The formula given for p above defines an explicit diffeomorphism between the complex projective line and the ordinary 2-sphere in 3-dimensional space. Alternatively, the point (z0, z1) can be mapped to the ratio z1/z0 in the Riemann sphere C.

Fiber bundle structure

The Hopf fibration defines a fiber bundle, with bundle projection p. This means that it has a "local product structure", in the sense that every point of the 2-sphere has some neighborhood U whose inverse image in the 3-sphere can be identified with the product of U and a circle: p−1(U) ≅ U×S1. Such a fibration is said to be locally trivial.

For the Hopf fibration, it is enough to remove a single point m from S2 and the corresponding circle p−1(m) from S3; thus one can take U = S2\{m}, and any point in S2 has a neighborhood of this form.

Geometric interpretation using rotations

Another geometric interpretation of the Hopf fibration can be obtained by considering rotations of the 2-sphere in ordinary 3-dimensional space. The rotation group SO(3) has a double cover, the spin group Spin(3), diffeomorphic to the 3-sphere. The spin group acts transitively on S2 by rotations. The stabilizer of a point is isomorphic to the circle group. It follows easily that the 3-sphere is a principal circle bundle over the 2-sphere, and this is the Hopf fibration.

To make this more explicit, there are two approaches: the group Spin(3) can either be identified with the group Sp(1) of unit quaternions, or with the special unitary group SU(2).

In the first approach, a vector (x1, x2, x3, x4) in R4 is interpreted as a quaternion qH by writing

The 3-sphere is then identified with the quaternions of unit norm, i.e., those qH for which |q|2 = 1, where |q|2 = q q, which is equal to x12 + x22 + x32 + x42 for q as above.

On the other hand, a vector (y1, y2, y3) in R3 can be interpreted as an imaginary quaternion

Then, as is well-known since Template:Harvtxt, the mapping

is a rotation in R3: indeed it is clearly an isometry, since |q p q|2 = q p q q p q = q p p q = |p|2, and it is not hard to check that it preserves orientation.

In fact, this identifies the group of unit quaternions with the group of rotations of R3, modulo the fact that the unit quaternions q and −q determine the same rotation. As noted above, the rotations act transitively on S2, and the set of unit quaternions q which fix a given unit imaginary quaternion p have the form q = u + v p, where u and v are real numbers with u2 + v2 = 1. This is a circle subgroup. For concreteness, one can take p = k, and then the Hopf fibration can be defined as the map sending a unit quaternion ω to ω k ω. All the quaternions ωq, where q is one of the circle of unit quaternions that fix k, get mapped to the same thing (which happens to be one of the two 180° rotations rotating k to the same place as ω does).

Another way to look at this fibration is that every unit quaternion ω moves the plane spanned by {1, k} to a new plane spanned by {ω, ωk}. Any quaternion ωq, where q is one of the circle of unit quaternions that fix k, will have the same effect. We put all these into one fibre, and the fibres can be mapped one-to-one to the 2-sphere of 180° rotations which is the range of ωkω*.

This approach is related to the direct construction by identifying a quaternion q = x1 + i x2 + j x3 + k x4 with the 2×2 matrix:

This identifies the group of unit quaternions with SU(2), and the imaginary quaternions with the skew-hermitian 2×2 matrices (isomorphic to C×R).

Explicit formulae

The rotation induced by a unit quaternion q = w + i x + j y + k z is given explicitly by the orthogonal matrix

Here we find an explicit real formula for the bundle projection. For, the fixed unit vector along the z axis, (0,0,1), rotates to another unit vector,

which is a continuous function of (w,x,y,z). That is, the image of q is where it aims the z axis. The fiber for a given point on S2 consists of all those unit quaternions that aim there.

To write an explicit formula for the fiber over a point (a,b,c) in S2, we may proceed as follows. Multiplication of unit quaternions produces composition of rotations, and

is a rotation by 2θ around the z axis. As θ varies, this sweeps out a great circle of S3, our prototypical fiber. So long as the base point, (a,b,c), is not the antipode, (0,0,−1), the quaternion

will aim there. Thus the fiber of (a,b,c) is given by quaternions of the form q(a,b,c)qθ, which are the S3 points

Since multiplication by q(a,b,c) acts as a rotation of quaternion space, the fiber is not merely a topological circle, it is a geometric circle. The final fiber, for (0,0,−1), can be given by using q(0,0,−1) = i, producing

which completes the bundle.

Thus, a simple way of visualizing the Hopf fibration is as follows. Any point on the 3-sphere is equivalent to a quaternion, which in turn is equivalent to a particular rotation of a Cartesian coordinate frame in three dimensions. The set of all possible quaternions produces the set of all possible rotations, which moves the tip of one unit vector of such a coordinate frame (say, the z vector) to all possible points on a unit 2-sphere. However, fixing the tip of the z vector does not specify the rotation fully; a further rotation is possible about the z-axis. Thus, the 3-sphere is mapped onto the 2-sphere, plus a single rotation.

Fluid Mechanics

If the Hopf fibration is treated as a vector field in 3 dimensional space then there is a solution to the (compressible, non-viscous) Navier-Stokes equations of fluid dynamics in which the fluid flows along the circles of the projection of the Hopf fibration in 3 dimensional space. The size of the velocities, the density and the pressure can be chosen at each point to satisfy the equations. All these quantities fall to zero going away from the centre. If a is the distance to the inner ring, the velocities, pressure and density fields are given by:

for arbitrary constants A and B. Similar patterns of fields are found as soliton solutions of magnetohydrodynamics:[1]

Generalizations

The Hopf construction, viewed as a fiber bundle p: S3CP1, admits several generalizations, which are also often known as Hopf fibrations. First, one can replace the projective line by an n-dimensional projective space. Second, one can replace the complex numbers by any (real) division algebra, including (for n = 1) the octonions.

Real Hopf fibrations

A real version of the Hopf fibration is obtained by regarding the circle S1 as a subset of R2 in the usual way and by idenitifying antipodal points. This gives a fiber bundle S1RP1 over the real projective line with fiber S0 = {1, -1}. Just as CP1 is diffeomorphic to a sphere, RP1 is diffeomorphic to a circle.

More generally, the n-sphere Sn fibers over real projective space RPn with fiber S0.

Complex Hopf fibrations

The Hopf construction gives circle bundles p : S2n+1CPn over complex projective space. This is actually the restriction of the tautological line bundle over CPn to the unit sphere in Cn+1.

Quaternionic Hopf fibrations

Similarly, one can regard S4n+3 as lying in Hn+1 (quaternionic n-space) and factor out by unit quaternion (= S3) multiplication to get HPn. In particular, since S4 = HP1, there is a bundle S7S4 with fiber S3.

Octonionic Hopf fibrations

A similar construction with the octonions yields a bundle S15S8 with fiber S7. But the sphere S31 does not fiber over S16 with fiber S15. One can regard S8 as the octonionic projective line OP1. Although one can also define an octonionic projective plane OP2, the sphere S23 does not fiber over OP2 with fiber S7.[2][3]

Fibrations between spheres

Sometimes the term "Hopf fibration" is restricted to the fibrations between spheres obtained above, which are

  • S1S1 with fiber S0
  • S3S2 with fiber S1
  • S7S4 with fiber S3
  • S15S8 with fiber S7

As a consequence of Adams' theorem, fiber bundles with spheres as total space, base space, and fiber can occur only in these dimensions. Fiber bundles with similar properties, but different from the Hopf fibrations, were used by John Milnor to construct exotic spheres.

Geometry and applications

The fibers of the Hopf fibration stereographically project to a family of Villarceau circles in R3.

The Hopf fibration has many implications, some purely attractive, others deeper. For example, stereographic projection S3R3 induces a remarkable structure in R3, which in turn illuminates the topology of the bundle Template:Harv. Stereographic projection preserves circles and maps the Hopf fibers to geometrically perfect circles in R3 which fill space. Here there is one exception: the Hopf circle containing the projection point maps to a straight line in R3 — a "circle through infinity".

The fibers over a circle of latitude on S2 form a torus in S3 (topologically, a torus is the product of two circles) and these project to nested toruses in R3 which also fill space. The individual fibers map to linking Villarceau circles on these tori, with the exception of the circle through the projection point and the one through its opposite point: the former maps to a straight line, the latter to a unit circle perpendicular to, and centered on, this line, which may be viewed as a degenerate torus whose radius has shrunken to zero. Every other fiber image encircles the line as well, and so, by symmetry, each circle is linked through every circle, both in R3 and in S3. Two such linking circles form a Hopf link in R3

Hopf proved that the Hopf map has Hopf invariant 1, and therefore is not null-homotopic. In fact it generates the homotopy group π3(S2) and has infinite order.

In quantum mechanics, the Riemann sphere is known as the Bloch sphere, and the Hopf fibration describes the topological structure of a quantum mechanical two-level system or qubit. Similarly, the topology of a pair of entangled two-level systems is given by the Hopf fibration

Template:Harv.

Discrete examples

Two rings of 10 dodecahedra of the 120-cell

Before you choose any particular company it is vital to understand in full how the different plans can vary. There is no other better method than to create a message board so that people can relax and "chill" on your website and check out your articles more. You should read the HostGator review, even before registering with a web hosting company. but Hostgator in addition considers the surroundings. You can even use a Hostgator reseller coupon for unlimited web hosting at HostGator! Most of individuals by no means go for yearly subscription and choose month to month subscription. Several users commented that this was the deciding factor in picking HostGator but in any case there is a 45 day Money Back Guarantee and there is no contract so you can cancel at any time. GatorBill is able to send you an email notice about the new invoice. In certain cases a dedicated server can offer less overhead and a bigger revenue in investments. With the plan come a Free Billing Executive, Free sellers account and Free Hosting Templates.



This is one of the only things that require you to spend a little money to make money. Just go make an account, get a paypal account, and start selling. To go one step beyond just affiliating products and services is to create your own and sell it through your blog. Not great if you really enjoy trying out all the themes. Talking in real time having a real person causes it to be personal helping me personally to sort out how to proceed. The first step I took was search for a discount code, as I did with HostGator. Using a HostGator coupon is a beneficial method to get started. As long as the necessities are able to preserve the horizontal functionality of your site, you would pretty much be fine. Three of the six regular 4-polytopes – 8-cell (tesseract), 24-cell, and 120-cell – can each be partitioned into disjoint great circle (regular polygon) rings of cells forming discrete Hopf fibrations of these polytopes. The tesseract partitions into two interlocking rings of four cubes each. The 24-cell partitions into four rings of six octahedrons each. The 120-cell partitions[4] into twelve rings of ten dodecahedra each. The 24-cell also contains a fibration of six rings of four octahedrons each stacked end to end at their vertices.

The 600-cell partitions into 20 rings of 30 tetrahedra each in a very interesting, quasi-periodic chain called the Boerdijk–Coxeter helix. When superimposed onto the 3-sphere curvature it becomes periodic with a period of 10 vertices, encompassing all 30 cells. In addition, the 16-cell partitions into two 8-tetrahedron chains, four edges long, and the 5-cell partitions into a single degenerate 5-tetrahedron chain.

The above fibrations all map to the following specific tilings of the 2-sphere.[4]

S3 S2 # of rings # of cells per ring Cell Stacking
600-cell {3,3,5} Icosahedron {3,5} 20 30 Boerdijk–Coxeter helix
120-cell {5,3,3} Dodecahedron {5,3} 12 10 face stacking
24-cell {3,4,3} Tetrahedron {3,3} 4 6 face stacking
Cube {4,3} 6 4 vertex stacking
16-cell {3,3,4} Dihedron {n,2} 2 8 Boerdijk–Coxeter helix
8-cell {4,3,3} Dihedron {n,2} 2 4 face stacking
5-cell {3,3,3} Whole 2-sphere 1 5 Boerdijk–Coxeter helix

References

  1. Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

    Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

    In case you are in search of an actual estate or Singapore property agent on-line, you simply should belief your intuition. It's because you do not know which agent is nice and which agent will not be. Carry out research on several brokers by looking out the internet. As soon as if you end up positive that a selected agent is dependable and reliable, you can choose to utilize his partnerise in finding you a home in Singapore. Most of the time, a property agent is taken into account to be good if he or she locations the contact data on his website. This may mean that the agent does not mind you calling them and asking them any questions relating to new properties in singapore in Singapore. After chatting with them you too can see them in their office after taking an appointment.

    Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

    Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

    15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

    To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010
  2. 20 year-old Real Estate Agent Rusty from Saint-Paul, has hobbies and interests which includes monopoly, property developers in singapore and poker. Will soon undertake a contiki trip that may include going to the Lower Valley of the Omo.

    My blog: http://www.primaboinca.com/view_profile.php?userid=5889534 (§0.26 on page 6)
  3. sci.math.research 1993 thread "Spheres fibred by spheres"
  4. 4.0 4.1 Template:Cite web
  • Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

    Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

    In case you are in search of an actual estate or Singapore property agent on-line, you simply should belief your intuition. It's because you do not know which agent is nice and which agent will not be. Carry out research on several brokers by looking out the internet. As soon as if you end up positive that a selected agent is dependable and reliable, you can choose to utilize his partnerise in finding you a home in Singapore. Most of the time, a property agent is taken into account to be good if he or she locations the contact data on his website. This may mean that the agent does not mind you calling them and asking them any questions relating to new properties in singapore in Singapore. After chatting with them you too can see them in their office after taking an appointment.

    Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

    Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

    15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

    To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010; reprinted as article 20 in Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

    Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

    In case you are in search of an actual estate or Singapore property agent on-line, you simply should belief your intuition. It's because you do not know which agent is nice and which agent will not be. Carry out research on several brokers by looking out the internet. As soon as if you end up positive that a selected agent is dependable and reliable, you can choose to utilize his partnerise in finding you a home in Singapore. Most of the time, a property agent is taken into account to be good if he or she locations the contact data on his website. This may mean that the agent does not mind you calling them and asking them any questions relating to new properties in singapore in Singapore. After chatting with them you too can see them in their office after taking an appointment.

    Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

    Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

    15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

    To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010
  • Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

    Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

    In case you are in search of an actual estate or Singapore property agent on-line, you simply should belief your intuition. It's because you do not know which agent is nice and which agent will not be. Carry out research on several brokers by looking out the internet. As soon as if you end up positive that a selected agent is dependable and reliable, you can choose to utilize his partnerise in finding you a home in Singapore. Most of the time, a property agent is taken into account to be good if he or she locations the contact data on his website. This may mean that the agent does not mind you calling them and asking them any questions relating to new properties in singapore in Singapore. After chatting with them you too can see them in their office after taking an appointment.

    Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

    Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

    15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

    To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010
  • Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

    Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

    In case you are in search of an actual estate or Singapore property agent on-line, you simply should belief your intuition. It's because you do not know which agent is nice and which agent will not be. Carry out research on several brokers by looking out the internet. As soon as if you end up positive that a selected agent is dependable and reliable, you can choose to utilize his partnerise in finding you a home in Singapore. Most of the time, a property agent is taken into account to be good if he or she locations the contact data on his website. This may mean that the agent does not mind you calling them and asking them any questions relating to new properties in singapore in Singapore. After chatting with them you too can see them in their office after taking an appointment.

    Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

    Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

    15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

    To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010
  • Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

    Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

    In case you are in search of an actual estate or Singapore property agent on-line, you simply should belief your intuition. It's because you do not know which agent is nice and which agent will not be. Carry out research on several brokers by looking out the internet. As soon as if you end up positive that a selected agent is dependable and reliable, you can choose to utilize his partnerise in finding you a home in Singapore. Most of the time, a property agent is taken into account to be good if he or she locations the contact data on his website. This may mean that the agent does not mind you calling them and asking them any questions relating to new properties in singapore in Singapore. After chatting with them you too can see them in their office after taking an appointment.

    Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

    Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

    15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

    To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010
  • Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

    Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

    In case you are in search of an actual estate or Singapore property agent on-line, you simply should belief your intuition. It's because you do not know which agent is nice and which agent will not be. Carry out research on several brokers by looking out the internet. As soon as if you end up positive that a selected agent is dependable and reliable, you can choose to utilize his partnerise in finding you a home in Singapore. Most of the time, a property agent is taken into account to be good if he or she locations the contact data on his website. This may mean that the agent does not mind you calling them and asking them any questions relating to new properties in singapore in Singapore. After chatting with them you too can see them in their office after taking an appointment.

    Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

    Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

    15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

    To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010.
  • Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

    Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

    In case you are in search of an actual estate or Singapore property agent on-line, you simply should belief your intuition. It's because you do not know which agent is nice and which agent will not be. Carry out research on several brokers by looking out the internet. As soon as if you end up positive that a selected agent is dependable and reliable, you can choose to utilize his partnerise in finding you a home in Singapore. Most of the time, a property agent is taken into account to be good if he or she locations the contact data on his website. This may mean that the agent does not mind you calling them and asking them any questions relating to new properties in singapore in Singapore. After chatting with them you too can see them in their office after taking an appointment.

    Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

    Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

    15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

    To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010
  • Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

    Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

    In case you are in search of an actual estate or Singapore property agent on-line, you simply should belief your intuition. It's because you do not know which agent is nice and which agent will not be. Carry out research on several brokers by looking out the internet. As soon as if you end up positive that a selected agent is dependable and reliable, you can choose to utilize his partnerise in finding you a home in Singapore. Most of the time, a property agent is taken into account to be good if he or she locations the contact data on his website. This may mean that the agent does not mind you calling them and asking them any questions relating to new properties in singapore in Singapore. After chatting with them you too can see them in their office after taking an appointment.

    Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

    Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

    15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

    To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010.

External links