Main Page: Difference between revisions

From formulasearchengine
Jump to navigation Jump to search
No edit summary
mNo edit summary
Line 1: Line 1:
{{Other uses2|Conformal}}
The '''Nash embedding theorems''' (or '''imbedding theorems'''), named after [[John Forbes Nash]], state that every [[Riemannian manifold]] can be isometrically [[embedding|embedded]] into some [[Euclidean space]].  Isometric means preserving the length of every [[rectifiable path|path]].  For instance, bending without stretching or tearing a page of paper gives an [[isometric embedding]] of the page into Euclidean space because curves drawn on the page retain the same [[arclength]] however the page is bent.
[[Image:Conformal map.svg|right|thumb|A rectangular grid (top) and its image under a conformal map ''f'' (bottom). It is seen that ''f'' maps pairs of lines intersecting at 90° to pairs of curves still intersecting at 90°.]]


In [[mathematics]], a '''conformal map''' is a [[function (mathematics)|function]] which preserves [[angle]]s. In the most common case the function is between domains in the [[complex plane]].
The first theorem is for [[continuously differentiable]] (''C''<sup>1</sup>) embeddings and the second for [[analytic function|analytic]] embeddings or embeddings that are [[smooth function|smooth]] of class ''C<sup>k</sup>'', 3 ≤ ''k'' ≤ ∞. These two theorems are very different from each other; the first one has a very simple proof and is very counterintuitive, while the proof of the second one is very technical but the result is not at all surprising.


More formally, a map,
The ''C''<sup>1</sup> theorem was published in 1954, the ''C<sup>k</sup>''-theorem in 1956.  The real analytic theorem was first treated by Nash in 1966; his argument was simplified considerably by {{harvtxt|Greene|Jacobowitz|1971}}. (A local version of this result was proved by [[Élie Cartan]] and [[Maurice Janet]] in the 1920s.)  In the real analytic case, the smoothing operators (see below) in the Nash inverse function argument can be replaced by Cauchy estimates.  Nash's proof of the ''C<sup>k</sup>''- case was later extrapolated into the [[h-principle]] and [[Nash–Moser theorem|Nash–Moser implicit function theorem]].  A simplified proof of the second Nash embedding theorem was obtained by {{harvtxt|Günther|1989}} who reduced the set of nonlinear [[partial differential equation]]s to an elliptic system, to which the [[contraction mapping theorem]] could be applied.


: <math>f: U \rightarrow V</math>
==Nash–Kuiper theorem (''C''<sup>1</sup> embedding theorem) {{anchor|Nash–Kuiper theorem}}==
'''Theorem.''' Let (''M'',''g'') be a Riemannian manifold and ƒ: ''M<sup>m</sup>'' → '''R'''<sup>''n''</sup> a [[short map|short]] ''C''<sup>∞</sup>-embedding (or [[Immersion (mathematics)|immersion]]) into Euclidean space '''R'''<sup>''n''</sup>, where ''n'' ≥ ''m''+1. Then for arbitrary ε > 0 there is an embedding (or immersion) ƒ<sub>ε</sub>: ''M<sup>m</sup>'' → '''R'''<sup>''n''</sup> which is
:(i) in class ''C''<sup>1</sup>,
:(ii) isometric: for any two vectors ''v'',''w''&nbsp;&isin;&nbsp;''T<sub>x</sub>''(''M'') in the [[tangent space]] at ''x'' &isin; ''M'',
:::<math>g(v,w)=\langle df_\epsilon(v),df_\epsilon(w)\rangle</math>,
:(iii) &epsilon;-close to ƒ:
:::|ƒ(''x'')&nbsp;&minus;&nbsp;ƒ<sub>&epsilon;</sub>(''x'')|&nbsp;<&nbsp;&epsilon; for all ''x''&nbsp;&isin;&nbsp;''M''.


is called '''conformal''' (or '''angle-preserving''') at {{math|{{var|u}}{{subsub|0}}}} if it preserves oriented angles between [[curve]]s through <math>\scriptstyle u_0</math> with respect to their [[orientation (mathematics)|orientation]] (i.e., not just the acute angle). Conformal maps preserve both angles and the shapes of infinitesimally small figures, but not necessarily their size.
In particular, as follows from the [[Whitney embedding theorem]], any ''m''-dimensional Riemannian manifold admits an isometric ''C''<sup>1</sup>-embedding into an ''arbitrarily small neighborhood'' in 2''m''-dimensional Euclidean space.


The conformal property may be described in terms of the [[Jacobian matrix and determinant|Jacobian]] derivative matrix of a [[coordinate system#Transformations|coordinate transformation]]. If the Jacobian matrix of the transformation is everywhere a scalar times a [[rotation matrix]], then the transformation is conformal.
The theorem was originally proved by John Nash with the condition ''n'' ≥ ''m''+2 instead of ''n'' ≥ ''m''+1 and generalized by [[Nicolaas Kuiper]], by a relatively easy trick.


Conformal maps can be defined between domains in higher dimensional [[Euclidean space]]s, and more generally on a [[Riemannian manifold|Riemannian]] or [[semi-Riemannian manifold]].
The theorem has many counterintuitive implications.  For example, it follows that any closed oriented Riemannian surface can be ''C''<sup>1</sup> isometrically embedded into an arbitrarily small [[ball (mathematics)|&epsilon;-ball]] in Euclidean 3-space (there is no such ''C''<sup>2</sup>-embedding since from the [[Gaussian_curvature#Alternative_Formulas|formula for the Gauss curvature]] an extremal point of such an embedding would have curvature ≥ &epsilon;<sup>-2</sup>).  And, there exist ''C''<sup>1</sup> isometric embeddings of the hyperbolic plane in '''R'''<sup>3</sup>.


==Complex analysis==
==''C''<sup>''k''</sup> embedding theorem==
An important family of examples of conformal maps comes from [[complex analysis]]. If ''U'' is an [[open set|open subset]] of the complex plane, <math>\scriptstyle\mathbb{C}</math>, then a [[function (mathematics)|function]]
The technical statement is as follows: if ''M'' is a given ''m''-dimensional Riemannian manifold (analytic or of class ''C<sup>k</sup>'', 3 ≤ ''k'' ≤ ∞), then there exists a number ''n'' (with ''n'' ≤ ''m''(3''m''+11)/2 if ''M'' is a compact manifold, or ''n'' ≤ ''m''(''m''+1)(3''m''+11)/2 if ''M'' is a non-compact manifold) and an [[injective]] map ƒ: ''M'' → '''R'''<sup>''n''</sup> (also analytic or of class ''C<sup>k</sup>'') such that for every point ''p'' of ''M'', the [[derivative]] dƒ<sub>''p''</sub> is a [[linear operator|linear map]] from the [[tangent space]] ''T<sub>p</sub>M'' to '''R'''<sup>''n''</sup> which is compatible with the given [[inner product space|inner product]] on ''T<sub>p</sub>M'' and the standard [[scalar product|dot product]] of '''R'''<sup>''n''</sup> in the following sense:
: &lang; ''u'', ''v'' &rang; = dƒ<sub>''p''</sub>(''u'') &middot; dƒ<sub>''p''</sub>(''v'')
for all vectors ''u'', ''v'' in ''T<sub>p</sub>M''. This is an undetermined system of [[partial differential equation]]s (PDEs).


: <math>f: U \rightarrow \mathbb{C}</math>
The Nash embedding theorem is a global theorem in the sense that the whole manifold is embedded into '''R'''<sup>''n''</sup>.  A local embedding theorem is much simpler and can be proved using the [[implicit function theorem]] of advanced calculus.{{Citation needed|date=November 2011}} The proof of the global embedding theorem relies on Nash's far-reaching generalization of the implicit function theorem, the [[Nash–Moser theorem]] and Newton's method with postconditioning. The basic idea of Nash's solution of the embedding problem is the use of [[Newton's method]] to prove the existence of a solution to the above system of PDEs. The standard Newton's method fails to converge when applied to the system; Nash uses smoothing operators defined by [[convolution]] to make the Newton iteration converge: this is Newton's method with postconditioning.  The fact that this technique furnishes a solution is in itself an [[existence theorem]] and of independent interest.  There is also an older method called [[Kantorovich iteration]] that uses Newton's method directly (without the introduction of smoothing operators).


is conformal [[if and only if]] it is [[holomorphic function|holomorphic]] and its [[derivative]] is everywhere non-zero on ''U''. If ''f'' is [[antiholomorphic function|antiholomorphic]] (that is, the [[complex conjugate|conjugate]] to a holomorphic function), it still preserves angles, but it reverses their orientation.
==References==
* {{citation|last=Greene|first=Robert E.|last2 = Jacobowitz|first2=Howard|title= Analytic Isometric Embeddings|journal=Annals of Mathematics|volume=93|pages=189–204|doi=10.2307/1970760|issue=1|publisher=The Annals of Mathematics, Vol. 93, No. 1|year=1971|jstor=1970760}}
* {{citation|first=Matthias|last=Günther|title=Zum Einbettungssatz von J. Nash [On the embedding theorem of J. Nash]|
journal=Math. Nachr.|volume= 144 |year=1989|pages= 165–187|doi=10.1002/mana.19891440113}}
*{{citation | last1 = Han|first1=Qing|last2=Hong|first2=Jia-Xing | title = Isometric Embedding of Riemannian Manifolds in Euclidean Spaces | publisher = American Mathematical Society | year = 2006 | isbn= 0-8218-4071-1}}
* {{citation|first=N.H.|last=Kuiper|authorlink=Nicolaas Kuiper|title=On ''C''<sup>1</sup>-isometric imbeddings I|journal=Nederl. Akad. Wetensch. Proc. Ser. A.|volume=58|year=1955|pages=545–556}}.
* {{citation|first=John|last=Nash|authorlink=John Forbes Nash, Jr.|title=''C''<sup>1</sup>-isometric imbeddings|journal=Annals of Mathematics|volume=60|year=1954|pages=383–396|doi=10.2307/1969840|issue=3|publisher=The Annals of Mathematics, Vol. 60, No. 3|jstor=1969840}}.
* {{citation|first=John|last=Nash|authorlink=John Forbes Nash, Jr.|title=The imbedding problem for Riemannian manifolds|journal=Annals of Mathematics|volume=63|year=1956|pages=20–63|doi=10.2307/1969989|issue=1|mr=0075639|jstor=1969989}}.
* {{citation|first=John|last=Nash|title=Analyticity of the solutions of implicit function problem with analytic data|authorlink=John Forbes Nash, Jr.|journal=Annals of Mathematics|volume=84|year=1966|pages=345–355|doi=10.2307/1970448|issue=3|publisher=The Annals of Mathematics, Vol. 84, No. 3|jstor=1970448}}.


The [[Riemann mapping theorem]], one of the profound results of complex analysis, states that any non-empty open [[simply connected]] proper subset of <math>\scriptstyle\mathbb{C}</math> admits a [[bijection|bijective]] conformal map to the open [[unit disk]] in <math>\scriptstyle\mathbb{C}</math>.
[[Category:Theorems in Riemannian geometry]]


A map of the [[Riemann sphere|extended complex plane]] (which is [[conformally equivalent]] to a sphere) [[surjection|onto]] itself is conformal if and only if it is a [[Möbius transformation]]. Again, for the [[complex conjugate|conjugate]], angles are preserved, but orientation is reversed.
[[de:Einbettungssatz von Nash]]
 
[[fr:Théorème de plongement de Nash]]
An example of the latter is taking the reciprocal of the conjugate, which corresponds to '''circle inversion''' with respect to the unit circle. This can also be expressed as taking the reciprocal of the radial coordinate in [[Circular coordinates#Circular coordinates|circular coordinates]], keeping the angle the same. See also [[inversive geometry]].
[[ru:Теорема Нэша о регулярных вложениях]]
 
[[zh:纳什嵌入定理]]
==Riemannian geometry==
{{see also|Conformal geometry}}
In [[Riemannian geometry]], two [[Riemannian metric]]s <math>\scriptstyle g</math> and <math>\scriptstyle h</math> on smooth manifold <math>M</math> are called '''conformally equivalent''' if <math>\scriptstyle g = u h </math> for some positive function <math>\scriptstyle u</math> on <math>\scriptstyle M</math>. The function <math>u</math> is called the '''conformal factor'''.
 
A [[diffeomorphism]] between two Riemannian manifolds is called a '''conformal map''' if the pulled back metric is conformally equivalent to the original one.  For example, [[stereographic projection]] of a [[sphere]] onto the [[plane (mathematics)|plane]] augmented with a [[point at infinity]] is a conformal map.
 
One can also define a '''conformal structure''' on a smooth manifold, as a class of conformally equivalent [[Riemannian metric]]s.
 
==Higher-dimensional Euclidean space==
A classical theorem of [[Joseph Liouville]] called [[Liouville's theorem (conformal mappings)|Liouville's theorem]] shows the higher-dimensions have less varied conformal maps:
 
Any conformal map on a portion of [[Euclidean space]] of dimension greater than 2 can be composed from three types of transformation: a [[homothetic transformation]], an [[isometry]], and a special conformal transformation. (A ''[[special conformal transformation]]'' is the composition of a reflection and an [[Inversion (geometry)|inversion in a sphere]].)  Thus, the group of conformal transformations in spaces of dimension greater than 2 are much more restricted than the planar case, where the [[Riemann mapping theorem]] provides a large group of conformal transformations.
 
==Uses==
If a function is [[harmonic function|harmonic]] (that is, it satisfies [[Laplace's equation]] <math>\scriptstyle\nabla^2 f=0</math>) over a particular space, and is transformed via a conformal map to another space, the transformation is also harmonic.  For this reason, any function which is defined by a [[potential]] can be transformed by a conformal map and still remain governed by a potential.  Examples in [[physics]] of equations defined by a potential include the [[electromagnetic field]], the [[gravitational field]], and, in [[fluid dynamics]], [[potential flow]], which is an approximation to fluid flow assuming constant [[density]], zero [[viscosity]], and [[irrotational vector field|irrotational flow]].  One example of a fluid dynamic application of a conformal map is the [[Joukowsky transform]].
 
Conformal mappings are invaluable for solving problems in engineering and physics that can be expressed in terms of functions of a complex variable but that exhibit inconvenient geometries. By choosing an appropriate mapping, the analyst can transform the inconvenient geometry into a much more convenient one. For example, one may wish to calculate the electric field, <math>\scriptstyle E(z),</math> arising from a point charge located near the corner of two conducting planes separated by a certain angle (where <math>\scriptstyle z</math> is the complex coordinate of a point in 2-space). This problem ''per se'' is quite clumsy to solve in closed form. However, by employing a very simple conformal mapping, the inconvenient angle is mapped to one of precisely pi radians, meaning that the corner of two planes is transformed to a straight line. In this new domain, the problem (that of calculating the electric field impressed by a point charge located near a conducting wall) is quite easy to solve. The solution is obtained in this domain, <math>\scriptstyle E(w),</math> and then mapped back to the original domain by noting that <math>\scriptstyle w</math> was obtained as a function (viz., the [[function composition|composition]] of <math>\scriptstyle E</math> and <math>\scriptstyle w</math>) of <math>\scriptstyle z,</math> whence <math>\scriptstyle E(w)</math> can be viewed as <math>\scriptstyle E(w(z)),</math> which is a function of <math>\scriptstyle z,</math> the original coordinate basis. Note that this application is not a contradiction to the fact that conformal mappings preserve angles, they do so only for points in the interior of their domain, and not at the boundary.
 
A large group of conformal maps for relating solutions of [[Maxwell’s equations]] was identified by [[Ebenezer Cunningham]] (1908) and [[Harry Bateman]] (1910). Their training at Cambridge University had given them facility with the [[method of image charges]] and associated methods of images for spheres and inversion. As recounted by Andrew Warwick (2003) ''Masters of Theory'':
: Each four-dimensional solution could be inverted in a four-dimensional hyper-sphere of pseudo-radius K in order to produce a new solution.
Warwick highlights (pages 404 to 424) this "new theorem of relativity" as a Cambridge response to Einstein, and as founded on exercises using the method of inversion, such as found in [[James Hopwood Jeans]] textbook ''Mathematical Theory of Electricity and Magnetism''.
 
In [[cartography]], several named [[Map_projection#Conformal|map projections]] (including the Mercator projection) are conformal.
 
In [[General Relativity]], conformal maps are the simplest and thus most common type of causal transformations. Physically, these describe different universes in which all the same events and interactions are still (causally) possible, but a new additional force is necessary to effect this (that is, replication of all the same trajectories would necessitate departures from [[geodesic]] motion because the [[Metric tensor|metric]] is different). It is often used to try to make models amenable to extension beyond [[Gravitational singularity|curvature singularities]], for example to permit description of the universe even before the [[big bang]].
 
==Alternative angles==
A ''conformal map'' is called that because it ''conforms to the principle of angle-preservation''. The presumption often is that the angle being preserved is the standard [[angle|Euclidean angle]], say parameterized in degrees or radians.  However, in plane mapping there are two other angles to consider: the [[hyperbolic angle]] and the [[slope]], which is the analogue of angle for [[dual number#Geometry|dual numbers]].
 
Suppose <math>\scriptstyle f: U \rightarrow \mathbb{V}</math> is a mapping of surfaces parameterized by <math>\scriptstyle (x,y)\,</math> and <math>\scriptstyle (u,v)\,</math>. The Jacobian matrix of <math>\scriptstyle f</math> is formed by the four [[partial derivative]]s of  <math>\scriptstyle u</math>  and  <math>\scriptstyle v</math>  with respect to <math>\scriptstyle x</math>  and <math>\scriptstyle y</math>.
 
If the Jacobian ''g'' has a non-zero [[determinant]], then <math>f</math> is "conformal in the generalized sense" with respect to one of the three angle types, depending on the [[2 × 2 real matrices|real matrix]] expressed by the Jacobian ''g''.
 
Indeed, any such ''g'' lies in a particular ''planar'' commutative [[subring]], and ''g'' has a polar coordinate form determined by parameters of radial and angular nature. The radial parameter corresponds to a [[similarity (geometry)|similarity mapping]] and can be taken as 1 for purposes of conformal examination. The angular parameter of ''g'' is one of the three types, shear, hyperbolic, or Euclidean:
* When the subring is isomorphic to the [[dual number]] plane, then ''g'' acts as a [[shear mapping]] and preserves the dual angle.
* When the subring is isomorphic to the [[split-complex number]] plane, then ''g'' acts as a [[squeeze mapping]] and preserves the hyperbolic angle.
* When the subring is isomorphic to the ordinary [[complex number]] plane, then ''g'' acts as a [[rotation]] and preserves the Euclidean angle.
While describing analytic [[motor variable#Bireal variable|functions of a bireal variable]], U. Bencivenga and G. Fox have written about conformal maps that preserve the hyperbolic angle.
 
==See also==
* [[Conformal pictures]]
* [[Schwarz–Christoffel mapping]]
* [[Penrose diagram]]
* [[Carathéodory's theorem (conformal mapping)|Carathéodory's theorem]]
 
== References ==
* {{Citation | last1=Ahlfors | first1=Lars V. | title=Conformal invariants: topics in geometric function theory | publisher=McGraw-Hill Book Co. | location=New York | mr=0357743 | year=1973}}
* {{Citation |last=Chanson |first=H. |authorlink=Hubert Chanson |title=Applied Hydrodynamics: An Introduction to Ideal and Real Fluid Flows |url=http://espace.library.uq.edu.au/view/UQ:191112 |publisher=CRC Press, Taylor & Francis Group, Leiden, The Netherlands, 478 pages |year=2009 |isbn=978-0-415-49271-3}}
* {{springer|id=C/c024780|title=Conformal mapping|author=E.P. Dolzhenko}}
* {{Citation | last1=Rudin | first1=Walter | author1-link=Walter Rudin | title=Real and complex analysis | publisher=McGraw-Hill Book Co. | location=New York | edition=3rd | isbn=978-0-07-054234-1 | mr=924157 | year=1987}}
* {{Citation | last1=Churchill | first1=Ruel V. | title=Complex Variables and Applications | publisher=McGraw-Hill Book Co. | location=New York | isbn=0-07-010855-2 | year=1974}}
* {{MathWorld | urlname=ConformalMapping | title=Conformal Mapping }}
 
== External links ==
* [http://math.fullerton.edu/mathews/c2003/ConformalMappingMod.html Conformal Mapping Module by John H. Mathews]{{Dead link|url=http://math.fullerton.edu/mathews/c2003/ConformalMappingMod.html|date=July 2011}}
* [http://virtualmathmuseum.org/galleryCM.html interactive visualizations of many conformal maps]
* [http://demonstrations.wolfram.com/ConformalMaps/ Conformal Maps] by Michael Trott, [[Wolfram Demonstrations Project]].
* [http://www-m10.ma.tum.de/twiki/bin/view/Lehre/Bsp10_6 Java applet] by Jürgen Richter-Gebert using [[Cinderella (software)|Cinderella]].
* [http://www.math.univ-montp2.fr/SPIP/IMG/jar/ComplexMapStill.jar Java applet] by Christian Mercat to deform pictures; [http://www.math.univ-montp2.fr/SPIP/IMG/jar/ComplexMap.jar MacOSX Java applet] that deforms the video flux from the webcam.
* [http://www.bru.hlphys.jku.at/conf_map/index.html Conformal Mapping images of current flow] in different geometries without and with magnetic field by Gerhard Brunthaler.
 
[[Category:Riemannian geometry]]
[[Category:Conformal mapping|*]]
[[Category:Cartographic projections]]
[[Category:Angle]]
 
[[ar:إسقاط تشكيلي]]
[[cs:Konformní zobrazení]]
[[de:Konforme Abbildung]]
[[es:Transformación conforme]]
[[fr:Transformation conforme]]
[[ko:등각사상]]
[[hi:अनुकोण प्रतिचित्रण]]
[[it:Mappa conforme]]
[[he:העתקה קונפורמית]]
[[kk:Конформды бейнелеу]]
[[nl:Hoekgetrouwe projectie]]
[[ja:等角写像]]
[[nn:Konform avbilding]]
[[pl:Odwzorowanie równokątne]]
[[pt:Projecção conforme]]
[[ru:Конформное отображение]]
[[sv:Konform avbildning]]
[[tr:Açıkorur gönderim]]
[[uk:Конформне відображення]]
[[zh:共形映射]]

Revision as of 15:46, 9 August 2014

The Nash embedding theorems (or imbedding theorems), named after John Forbes Nash, state that every Riemannian manifold can be isometrically embedded into some Euclidean space. Isometric means preserving the length of every path. For instance, bending without stretching or tearing a page of paper gives an isometric embedding of the page into Euclidean space because curves drawn on the page retain the same arclength however the page is bent.

The first theorem is for continuously differentiable (C1) embeddings and the second for analytic embeddings or embeddings that are smooth of class Ck, 3 ≤ k ≤ ∞. These two theorems are very different from each other; the first one has a very simple proof and is very counterintuitive, while the proof of the second one is very technical but the result is not at all surprising.

The C1 theorem was published in 1954, the Ck-theorem in 1956. The real analytic theorem was first treated by Nash in 1966; his argument was simplified considerably by Template:Harvtxt. (A local version of this result was proved by Élie Cartan and Maurice Janet in the 1920s.) In the real analytic case, the smoothing operators (see below) in the Nash inverse function argument can be replaced by Cauchy estimates. Nash's proof of the Ck- case was later extrapolated into the h-principle and Nash–Moser implicit function theorem. A simplified proof of the second Nash embedding theorem was obtained by Template:Harvtxt who reduced the set of nonlinear partial differential equations to an elliptic system, to which the contraction mapping theorem could be applied.

Nash–Kuiper theorem (C1 embedding theorem) <Nash–Kuiper theorem>...</Nash–Kuiper theorem>

Theorem. Let (M,g) be a Riemannian manifold and ƒ: MmRn a short C-embedding (or immersion) into Euclidean space Rn, where nm+1. Then for arbitrary ε > 0 there is an embedding (or immersion) ƒε: MmRn which is

(i) in class C1,
(ii) isometric: for any two vectors v,w ∈ Tx(M) in the tangent space at xM,
,
(iii) ε-close to ƒ:
|ƒ(x) − ƒε(x)| < ε for all x ∈ M.

In particular, as follows from the Whitney embedding theorem, any m-dimensional Riemannian manifold admits an isometric C1-embedding into an arbitrarily small neighborhood in 2m-dimensional Euclidean space.

The theorem was originally proved by John Nash with the condition nm+2 instead of nm+1 and generalized by Nicolaas Kuiper, by a relatively easy trick.

The theorem has many counterintuitive implications. For example, it follows that any closed oriented Riemannian surface can be C1 isometrically embedded into an arbitrarily small ε-ball in Euclidean 3-space (there is no such C2-embedding since from the formula for the Gauss curvature an extremal point of such an embedding would have curvature ≥ ε-2). And, there exist C1 isometric embeddings of the hyperbolic plane in R3.

Ck embedding theorem

The technical statement is as follows: if M is a given m-dimensional Riemannian manifold (analytic or of class Ck, 3 ≤ k ≤ ∞), then there exists a number n (with nm(3m+11)/2 if M is a compact manifold, or nm(m+1)(3m+11)/2 if M is a non-compact manifold) and an injective map ƒ: MRn (also analytic or of class Ck) such that for every point p of M, the derivativep is a linear map from the tangent space TpM to Rn which is compatible with the given inner product on TpM and the standard dot product of Rn in the following sense:

u, v ⟩ = dƒp(u) · dƒp(v)

for all vectors u, v in TpM. This is an undetermined system of partial differential equations (PDEs).

The Nash embedding theorem is a global theorem in the sense that the whole manifold is embedded into Rn. A local embedding theorem is much simpler and can be proved using the implicit function theorem of advanced calculus.Potter or Ceramic Artist Truman Bedell from Rexton, has interests which include ceramics, best property developers in singapore developers in singapore and scrabble. Was especially enthused after visiting Alejandro de Humboldt National Park. The proof of the global embedding theorem relies on Nash's far-reaching generalization of the implicit function theorem, the Nash–Moser theorem and Newton's method with postconditioning. The basic idea of Nash's solution of the embedding problem is the use of Newton's method to prove the existence of a solution to the above system of PDEs. The standard Newton's method fails to converge when applied to the system; Nash uses smoothing operators defined by convolution to make the Newton iteration converge: this is Newton's method with postconditioning. The fact that this technique furnishes a solution is in itself an existence theorem and of independent interest. There is also an older method called Kantorovich iteration that uses Newton's method directly (without the introduction of smoothing operators).

References

  • 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.

de:Einbettungssatz von Nash fr:Théorème de plongement de Nash ru:Теорема Нэша о регулярных вложениях zh:纳什嵌入定理