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| {{More footnotes|date=April 2010}}
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| {{cite check|date=April 2010}}
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| {{Original research|data=June 2013|date=June 2013}}
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| The [[language of mathematics]] has a vast [[vocabulary]] of specialist and technical terms. It also has a certain amount of '''[[jargon]]''': commonly used phrases which are part of the culture of mathematics, rather than of the subject. Jargon often appears in lectures, and sometimes in print, as informal shorthand for rigorous arguments or precise ideas. Much of this is common English, but with a specific non-obvious meaning when used in a mathematical sense.
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| __TOC__
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| Some phrases, like "in general", appear below in more than one section.
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| ==Philosophy of mathematics==
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| ; [[abstract nonsense]]{{anchor|abstract nonsense}}: Also ''general abstract nonsense'' or ''generalized abstract nonsense'', a tongue-in-cheek reference to [[category theory]], using which one can employ arguments that establish a (possibly concrete) result without reference to any specifics of the present problem.
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| {{quote|[The paper of {{Harvard citations|last2 = Mac Lane|last1 = Eilenberg|year = 1942|txt = yes}}] introduced the very abstract idea of a 'category' — a subject then called 'general abstract nonsense'!|{{Harvard citations|last = Mac Lane|first = Saunders|year = 1997|txt=yes}}}}
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| {{quote|[Grothendieck] raised algebraic geometry to a new level of abstraction...if certain mathematicians could console themselves for a time with the hope that all these complicated structures were 'abstract nonsense'...the later papers of Grothendieck and others showed that classical problems...which had resisted efforts of several generations of talented mathematicians, could be solved in terms of...complicated concepts.|{{Harvard citations|last = Monastyrsky|first = Michael|year = 2001|txt = yes}}}}
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| ; [[canonical form|canonical]]{{anchor|canonical}}: A reference to a standard or choice-free presentation of some mathematical object. The term ''canonical'' is also used more informally, meaning roughly "standard" or "classic". For example, one might say that [[Euclid]]'s proof is the "canonical proof" of the infinitude of primes.
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| {{quote|1=There are two canonical proofs that are always used to show non-mathematicians what a mathematical proof is like:<br/><p style="text-indent: 1em;">—The proof that there are infinitely many prime numbers.</p><p style="text-indent: 1em;">—The proof of the irrationality of the square root of two.</p>|2={{Harvard citations|last = Wiedijk|first = Freek|year = 2006|txt = yes|loc = p.2}}}}
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| ; deep{{anchor|deep}}: A result is called "deep" if its proof requires concepts and methods that are advanced beyond the concepts needed to formulate the result. The [[prime number theorem]], proved with techniques from [[complex analysis]], was thought to be a deep result until [[elementary proof]]s were found. The fact that [[π]] is irrational is a deep result because it requires considerable development of [[real analysis]] to prove, even though it can be stated in terms of simple number theory and geometry.
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| ; [[mathematical beauty|elegant]]{{anchor|elegant}}: Also ''beautiful''; an aesthetic term referring to the ability of an idea to provide insight into mathematics, whether by unifying disparate fields, introducing a new perspective on a single field, or providing a technique of proof which is either particularly simple, or captures the intuition or imagination as to why the result it proves is true. [[Gian-Carlo Rota]] distinguished between ''elegance of presentation'' and ''beauty of concept'', saying that for example, some topics could be written about elegantly although the mathematical content is not beautiful, and some theorems or proofs are beautiful but may be written about inelegantly.
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| {{quote|The beauty of a mathematical theory is independent of the aesthetic qualities...of the theory's rigorous expositions. Some beautiful theories may never be given a presentation which matches their beauty....Instances can also be found of mediocre theories of questionable beauty which are given brilliant, exciting expositions....[Category theory] is rich in beautiful and insightful definitions and poor in elegant proofs....[The theorems] remain clumsy and dull....[Expositions of [[projective geometry]]] vied for one another in elegance of presentation and in cleverness of proof....In retrospect, one wonders what all the fuss was about.<br/><br/>Mathematicians may say that a theorem is beautiful when they really mean to say that it is enlightening. We acknowledge a theorem's beauty when we see how the theorem 'fits' in its place....We say that a proof is beautiful when such a proof finally gives away the secret of the theorem....|{{Harvard citations|last = Rota|first = Gian-Carlo|year = 1977|loc1 = pp.173–174|loc2 = pp.181–182|txt = yes}}}}
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| ; [[elementary proof|elementary]]{{anchor|elementary}}: A proof or result is called "elementary" if it requires only basic concepts and methods, in contrast to so-called [[#deep|deep]] results. The concept of "elementary proof" is used specifically in [[number theory]], where it usually refers to a proof that does not use methods from [[complex analysis]].
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| ; [[mathematical folklore|folklore]] {{anchor|folklore}}: A result is called "folklore" if it is non-obvious, has not been published, and yet is generally known among the specialists in a field. Usually, it is unknown who first obtained the result. If the result is important, it may eventually find its way into the textbooks, whereupon it ceases to be folklore.
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| {{quote|Many of the results mentioned in this paper should be considered "folklore" in that they merely formally state ideas that are well-known to researchers in the area, but may not be obvious to beginners and to the best of my knowledge do not appear elsewhere in print.|{{Harvard citations |last=Impagliazzo |first=Russell |year=1995 |txt= yes}}}}
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| ; [[natural transformation|natural]]{{anchor|natural}}: Similar to "canonical" but more specific, this term makes reference to a description (almost exclusively in the context of [[transformation (mathematics)|transformation]]s) which holds independently of any choices. Though long used informally, this term has found a formal definition in category theory.
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| ; [[pathological (mathematics)|pathological]]{{anchor|pathological}}: An object behaves pathologically if it fails to conform to the generic behavior of such objects, fails to satisfy certain regularity properties (depending on context), or simply disobeys mathematical intuition. These can be and often are contradictory requirements. Sometimes the term is more pointed, referring to an object which is specifically and artificially exhibited as a counterexample to these properties.
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| {{quote|Since half a century we have seen arise a crowd of bizarre functions which seem to try to resemble as little as possible the honest functions which serve some purpose....Nay more, from the logical point of view, it is these strange functions which are the most general....to-day they are invented expressly to put at fault the reasonings of our fathers....|{{Harvard citations|last = Poincaré|first = Henri|year = 1913|txt = yes}}}}
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| {{quote|[The [[Dirichlet function]]] took on an enormous importance...as giving an incentive for the creation of new types of function whose properties departed completely from what intuitively seemed admissible. A celebrated example of such a so-called 'pathological' function...is [[Weierstrass function|the one provided by Weierstrass]]....This function is continuous but not differentiable.|{{Harvard citations|last = Pinto|first = J. Sousa|year = 2004|txt = yes}}}}
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| ; [[Rigour#Mathematical rigour|rigor (rigour)]]{{anchor|rigour)}}: Mathematics strives to establish its results using indisputable logic rather than informal descriptive argument. Rigor is the use of such logic in a proof.
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| ; [[well-behaved]]{{anchor|well-behaved}}: An object is well-behaved (in contrast with being ''[[#pathological|pathological]]'') if it ''does'' satisfy the prevailing regularity properties, or sometimes if it conforms to intuition (but intuition often suggests the opposite behavior as well).
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| ==Descriptive informalities==
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| Although ultimately every mathematical argument must meet a high standard of precision, mathematicians use descriptive but informal statements to discuss recurring themes or concepts with unwieldy formal statements. Note that many of the terms are completely rigorous in context.
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| ; [[almost all]]{{anchor|almost all}}: A shorthand term for "all except for a set of [[measure zero]]", when there is a measure to speak of. For example, "almost all [[real numbers]] are [[transcendental number|transcendental]]" because the [[algebraic numbers|algebraic real numbers]] form a [[countable]] subset of the real numbers with measure zero. One can also speak of "almost all" [[integers]] having a property to mean "all but finitely many", despite the integers not admitting a measure for which this agrees with the previous usage. For example, "almost all [[prime number]]s are odd". There is a more complicated meaning for integers as well, discussed in the main article. Finally, this term is sometimes used synonymously with ''generic'', below.
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| ; [[arbitrarily large]]{{anchor|arbitrarily large}}{{anchor|arbitrarily small}}{{anchor|arbitrarily close}}: Notions which arise mostly in the context of limits, referring to the recurrence of a phenomenon as the limit is approached. A statement such as that predicate ''P'' is satisfied by arbitrarily large values, can be expressed in more formal notation by {{nowrap|∀''x'' : ∃''y'' ≥ ''x'' : ''P''(''y'')}}. See also ''frequently''. The statement that quantity ''f''(''x'') depending on ''x'' "can be made" arbitrarily large, corresponds to {{nowrap|∀''y'' : ∃''x'' : ''f''(''x'') ≥ ''y''}}.
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| ; [[arbitrary]]{{anchor|arbitrary}}: A shorthand for the universal quantifier. An arbitrary choice is one which is made unrestrictedly, or alternatively, a statement holds of an arbitrary element of a set if it holds of any element of that set.
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| ; eventually{{anchor|eventually}}, [[Definiteness|definitely]]: In the context of limits, this is shorthand ''for sufficiently large arguments''; the relevant argument(s) are implicit in the context. As an example, one could say that "The function ''log''(''log''(''x'')) ''eventually'' becomes larger than 100"; in this context, "eventually" means "for [[#sufficiently large|sufficiently large]] ''x''".
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| ; factor through{{anchor|factor through}}<!-- This anchor is linked from [[Exact category]] -->: A term in [[category theory]] referring to composition of morphisms. If we have three objects ''A'', ''B'', and ''C'' and a map <math>f \colon A \to C</math> which is written as a composition <math>f = h \circ g</math> with <math>g \colon A \to B</math> and <math>h \colon B \to C</math>, then ''f'' is said to ''factor through'' any (and all) of <math>B</math>, <math>g</math>, and <math>h</math>.
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| ; finite{{anchor|finite}}: Next to the usual meaning of "not infinite", in another more restrictive meaning that one may encounter, a value being said to be "finite" also excludes [[infinitesimal]] values and the value 0. For example, if the [[variance]] of a random variable is said to be finite, this implies it is a positive real number.
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| ; frequently{{anchor|frequently}}: In the context of limits, this is shorthand for ''[[#arbitrarily large|arbitrarily large]] arguments'' and its relatives; as with ''eventually'', the intended variant is implicit. As an example, one could say that "The function ''sin''(''x'') is frequently zero", where "frequently" means "for arbitrarily large ''x''".
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| ; [[Generic property|generic]]{{anchor|generic}}: This term has similar connotations as ''almost all'' but is used particularly for concepts outside the purview of [[measure theory]]. A property holds "generically" on a set if the set satisfies some (context-dependent) notion of density, or perhaps if its complement satisfies some (context-dependent) notion of smallness. For example, a property which holds on a [[Dense set|dense]] '''G'''<sub>δ</sub> (intersection of countably many open sets) is said to hold generically. In [[algebraic geometry]], one says that a property of points on an [[algebraic variety]] that holds on a dense [[Zariski topology|Zariski open]] set is true generically; however, it is usually not said that a property which holds merely on a dense set (which is not Zariski open) is generic in this situation.
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| ; in general{{anchor|in general}}: In a descriptive context, this phrase introduces a simple characterization of a broad class of objects, with an eye towards identifying a unifying principle. This term introduces an "elegant" description which holds for "[[#arbitrary|arbitrary]]" objects. Exceptions to this description may be mentioned explicitly, as "[[#pathological|pathological]]" cases.
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| {{quote|Norbert A’Campo of the University of Basel once asked Grothendieck about something related to the Platonic solids. Grothendieck advised caution. The Platonic solids are so beautiful and so exceptional, he said, that one cannot assume such exceptional beauty will hold in more general situations.|{{Harvard citations|last=Jackson|first = Allyn|year=2004|loc = p.1197|txt = yes}}}}
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| ; [[Sides of an equation|left-hand side, right-hand side]] (LHS, RHS){{anchor|LHS|RHS}}: Most often, these refer simply to the left-hand or the right-hand side of an equation; for example, <math>x = y + 1</math> has ''x'' on the LHS and ''y + 1'' on the RHS. Occasionally, these are used in the sense of [[Value (computer science)|lvalue]] and rvalue: an RHS is primitive, and an LHS is derivative.
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| ; nice{{anchor|proper}}: A mathematical object is colloquially called ''nice'' or ''sufficiently nice'' if it satisfies hypotheses or properties, sometimes unspecified or even unknown, that are especially desirable in a given context. It is an informal antonym for [[Mathematical_jargon#pathological|pathological]]. For example, one might conjecture that a differential operator ought to satisfy a certain boundedness condition "for nice test functions," or one might state that some interesting topological invariant should be computable "for nice spaces ''X''."
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| ; proper{{anchor|proper}}: If, for some notion of substructure, objects are substructures of themselves (that is, the relationship is reflexive), then the qualification ''proper'' requires the objects to be different. For example, a ''proper'' subset of a set ''S'' is a [[subset]] of ''S'' that is different from ''S'', and a ''proper'' divisor of a number ''n'' is a divisor of ''n'' that is different from ''n''. This [[Operator overloading|overloaded]] word is also non-jargon for a [[proper morphism]].
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| ; regular {{anchor|regular}}: A function is called ''regular'' if it satisfies satisfactory continuity and differentiability properties, which are often context-dependent. These properties might include possessing a specified number of derivatives, with the function and its derivatives exhibiting some nice property, such as [[Hölder continuity]]. Informally, this term is sometimes used synonymously with ''smooth'', below. These imprecise uses of the word ''regular'' are not to be confused with the notion of a [[Regular space|regular topological space]], which is rigorously defined.
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| ; resp.{{anchor|resp.}}: (Respectively) A convention to shorten parallel expositions. "A (resp. B) [has some relationship to] X (resp. Y)" means that A [has some relationship to] X and also that B [has (the same) relationship to] Y. For example, squares (resp. triangles) have 4 sides (resp. 3 sides); or compact (resp. Lindelöf) spaces are ones where every open cover has a finite (resp. countable) open subcover.
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| ; sharp{{anchor|sharp}}: Often, a mathematical theorem will establish constraints on the behavior of some object; for example, a function will be shown to have an upper or lower bound. The constraint is ''sharp'' (sometimes ''optimal'') if it cannot be made more restrictive without failing in some cases. For example, for [[#arbitrary|arbitrary]] nonnegative real numbers ''x'', the exponential function ''e<sup>x</sup>'', where ''e'' = 2.7182818..., gives an upper bound on the values of the quadratic function ''x''<sup>2</sup>. This is not sharp; the gap between the functions is everywhere at least 1. Among the exponential functions of the form α<sup>''x''</sup>, setting α = ''e''<sup>2/''e''</sup> = 2.0870652... results in a sharp upper bound; the slightly smaller choice α = 2 fails to produce an upper bound, since then α<sup>3</sup> = 8 < 3<sup>2</sup>. In applied fields the word "tight" is often used with the same meaning.<ref>{{cite book|last=Boyd|first=Stephen|title=Convex Optimization|year=2004|publisher=Cambridge University Press|isbn=0521833787}}</ref>
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| ; [[smooth function|smooth]]{{anchor|smooth}}: ''Smoothness'' is a concept which mathematics has endowed with many meanings, from simple differentiability to infinite differentiability to analyticity, and still others which are more complicated. Each such usage attempts to invoke the physically intuitive notion of smoothness.
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| ; strong, stronger{{anchor|strong|stronger}}<!-- This anchor is linked from [[Intransitivity]] -->: A theorem is said to be ''strong'' if it deduces restrictive results from general hypotheses. One celebrated example is [[Donaldson's theorem]], which puts tight restraints on what would otherwise appear to be a large class of manifolds. This (informal) usage reflects the opinion of the mathematical community: not only should such a theorem be strong in the descriptive sense (below) but it should also be definitive in its area. A theorem, result, or condition is further called ''stronger'' than another one if a proof of the second can be easily obtained from the first. An example is the sequence of theorems: [[Fermat's little theorem]], [[Euler's theorem]], [[Lagrange's theorem (group theory)|Lagrange's theorem]], each of which is stronger than the last; another is that a sharp upper bound (see above) is a stronger result than a non-sharp one. Finally, the adjective ''strong'' or the adverb ''strongly'' may be added to a mathematical notion to indicate a related stronger notion; for example, a [[strong antichain]] is an [[antichain]] satisfying certain additional conditions, and likewise a [[strongly regular graph]] is a [[regular graph]] meeting stronger conditions. When used in this way, the stronger notion (such as "strong antichain") is a technical term with a precisely defined meaning; the nature of the extra conditions cannot be derived from the definition of the weaker notion (such as "antichain").
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| ; [[sufficiently large]], suitably small, sufficiently close{{anchor|sufficiently large|suitably small|sufficiently close}}: In the context of limits, these terms refer to some (unspecified, even unknown) point at which a phenomenon prevails as the limit is approached. A statement such as that predicate ''P'' holds for sufficiently large values, can be expressed in more formal notation by ∃''x'' : ∀''y'' ≥ ''x'' : ''P''(''y''). See also ''eventually''.
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| ; upstairs, downstairs{{anchor|upstairs|downstairs}}: A descriptive term referring to notation in which two objects are written one above the other; the upper one is ''upstairs'' and the lower, ''downstairs''. For example, in a [[fiber bundle]], the total space is often said to be ''upstairs'', with the base space ''downstairs''. In a [[fraction (mathematics)|fraction]], the numerator is occasionally referred to as ''upstairs'' and the [[denominator]] ''downstairs'', as in "bringing a term upstairs".
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| ; [[up to]], modulo, mod out by{{anchor|up to|modulo|mod out by}}: An extension to mathematical discourse of the notions of [[modular arithmetic]]. A statement is true ''up to'' a condition if the establishment of that condition is the only impediment to the truth of the statement. Also used when working with members of equivalence classes, esp. in [[category theory]], where the equivalence relation is (categorical) isomorphism; for example, "The tensor product in a weak monoidal category is associative and unital up to a natural isomorphism."
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| ; vanish{{anchor|vanish}}: To assume the value 0. For example, "The function sin(''x'') vanishes for those values of ''x'' that are integer multiples of π." This can also apply to limits: see [[Vanish at infinity]].
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| ; weak, weaker{{anchor|weak|weaker}}: The converse of [[Mathematical jargon#strong|strong]].
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| ; well-defined{{anchor|well-defined}}: Accurately and precisely described or specified.
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| ==Proof terminology==
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| The formal language of [[proof (mathematics)|proof]] draws repeatedly from a small pool of ideas, many of which are invoked through various lexical shorthands in practice.
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| ; aliter{{anchor|aliter}}: An obsolescent term which is used to announce to the reader an alternative method, or proof of a result. In a proof, it therefore flags a piece of reasoning that is superfluous from a logical point of view, but has some other interest.
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| ; [[proof by contradiction|by way of contradiction]] (BWOC), or "for, if not, ..."{{anchor|by way of contradiction|BWOC}}: The rhetorical prelude to a proof by contradiction, preceding the negation of the statement to be proved.
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| ; [[Iff#More general usage|if and only if]] (iff){{anchor|if and only if|iff}}: An abbreviation for [[logical equivalence]] of statements.
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| ; in general{{anchor|in general}}<!-- [[In general]] redirects here -->: In the context of proofs, this phrase is often seen in [[mathematical induction|induction]] arguments when passing from the base case to the "induction step", and similarly, in the definition of [[sequence (mathematics)|sequence]]s whose first few terms are exhibited as examples of the formula giving every term of the sequence.
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| ; [[necessary and sufficient]]{{anchor|necessary and sufficient}}: A minor variant on "if and only if"; ''necessary'' means "only if" and ''sufficient'' means '"if". For example, "For a [[field (mathematics)|field]] ''K'' to be [[algebraically closed field|algebraically closed]] it is necessary and sufficient that it have no finite [[field extension]]s" means "''K'' is algebraically closed if and only if it has no finite extensions". Often used in lists, as in "The following conditions are necessary and sufficient for a field to be algebraically closed...".
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| ; need to show (NTS), required to prove (RTP), wish to show, want to show (WTS){{anchor|need to show}}: Proofs sometimes proceed by enumerating several conditions whose satisfaction will together imply the desired theorem; thus, one ''needs to show'' just these statements.
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| ; [[one and only one]]{{anchor|one and only one}}: A statement of the uniqueness of an object; the object exists, and furthermore, no other such object exists.
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| ; [[Q.E.D.]]{{anchor|Q.E.D.}}: (''Quod erat demonstrandum''): A Latin abbreviation, meaning "which was to be demonstrated", historically placed at the end of proofs, but less common currently, having been supplanted by the [[Tombstone (typography)|Halmos end-of-proof mark]].
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| ; sufficiently nice{{anchor|sufficiently nice}}: A condition on objects in the scope of the discussion, to be specified later, that will guarantee that some stated property holds for them. When [[heuristics|working out]] a theorem, the use of this expression in the statement of the theorem indicates that the conditions involved may be not yet known to the speaker, and that the intent is to collect the conditions that will be found to be needed in order for the proof of the theorem to go through.
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| ; the following are equivalent (TFAE){{anchor|the following are equivalent|TFAE}}<!-- [[TFAE]] redirects here -->: Often several equivalent conditions (especially for a definition, such as [[normal subgroup]]) are equally useful in practice; one introduces a theorem stating an equivalence of more than two statements with TFAE.
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| ; [[transport of structure]]{{anchor|transport of structure}}: It is often the case that two objects are shown to be equivalent in some way, and that one of them is endowed with additional structure. Using the equivalence, we may define such a structure on the second object as well, via ''transport of structure''. For example, any two [[vector space]]s of the same dimension are isomorphic; if one of them is given an [[inner product]] and if we fix a particular isomorphism, then we may define an inner product on the other space by ''factoring through'' the isomorphism.
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| {{quote|1=Let ''V'' be a finite-dimensional vector space over ''k''....Let (''e''<sub>''i''</sub>)<sub>1 ≤ ''i'' ≤ ''n''</sub> be a basis for ''V''....There is an isomorphism of the polynomial algebra ''k''[''T''<sub>''ij''</sub>]<sub>1 ≤ ''i'',''j'' ≤ ''n''</sub> onto the algebra Sym<sub>''k''</sub>(''V'' ⊗ ''V''<sup>*</sup>)....It extends to an isomorphism of ''k''['''GL'''<sub>''n''</sub>] to the localized algebra Sym<sub>''k''</sub>(''V'' ⊗ ''V''<sup>*</sup>)<sub>''D''</sub>, where ''D'' = det(''e''<sub>''i''</sub> ⊗ ''e''<sub>''j''</sub><sup>*</sup>)....We write ''k''['''GL'''(''V'')] for this last algebra. By transport of structure, we obtain a linear algebraic group '''GL'''(''V'') isomorphic to '''GL'''<sub>''n''</sub>.|2={{Harvard citations|last = Shafarevich|first = Igor|year = 1991|loc = p.12|txt = yes}}}}
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| ; [[Without loss of generality|without (any) loss of generality]] (WLOG, WOLOG, WALOG), we may assume (WMA){{anchor|WLOG|WOLOG|WALOG|we may assume|WMA}}: Sometimes a proposition can be more easily proved with additional assumptions on the objects it concerns. If the proposition as stated follows from this modified one with a simple and minimal explanation (for example, if the remaining special cases are identical but for notation), then the modified assumptions are introduced with this phrase and the altered proposition is proved.
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| ==Proof techniques==
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| Mathematicians have several phrases to describe proofs or proof techniques. These are often used as hints for filling in tedious details.
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| ; angle chasing{{anchor|angle chasing}}: Used to describe a geometrical proof that involves finding relationships between the various angles in a diagram.<ref>{{Citation |title=Elementary Geometry|first=John|last=Roe
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| |publisher=Oxford science publications|year=1993|isbn=0-19-853456-6|page=119}}</ref>
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| ; [[back-of-the-envelope calculation]]{{anchor|back-of-the-envelope calculation}}: An informal computation omitting much rigor without sacrificing correctness. Often this computation is "proof of concept" and treats only an accessible special case.
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| ; by inspection{{anchor|by inspection}}: A rhetorical shortcut made by authors who invite the reader to verify, at a glance, the correctness of a proposed expression or deduction. If an expression can be evaluated by straightforward application of simple techniques and without recourse to extended calculation or general theory, then it can be evaluated ''by inspection''. It is also applied to solving equations; for example to find roots of a [[quadratic equation]] by inspection is to 'notice' them, or mentally check them. 'By inspection' can play a kind of ''[[wikt:gestalt|gestalt]]'' role: the answer or solution simply clicks into place.
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| ; clearly, can be easily shown{{anchor|clearly}}: A term which shortcuts around calculation the mathematician perceives to be tedious or routine, accessible to any member of the audience with the necessary expertise in the field; [[Pierre Laplace|Laplace]] used ''obvious'' ([[French language|French]]: ''évident'').
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| ; [[diagram chasing]]{{anchor|diagram chasing|diagram chase}}:<ref>Numerous examples can be found in {{Harvard citations|last = Mac Lane|year = 1998}}, for example on p. 100.</ref> Given a [[commutative diagram]] of objects and morphisms between them, if one wishes to prove some property of the morphisms (such as [[injectivity]]) which can be stated in terms of [[element (category theory)|element]]s, then the proof can proceed by tracing the path of elements of various objects around the diagram as successive morphisms are applied to it. That is, one ''chases'' elements around the diagram, or does a ''diagram chase''.
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| ; [[handwaving]]{{anchor|handwaving}}: A non-technique of proof mostly employed in lectures, where formal argument is not strictly necessary. It proceeds by omission of details or even significant ingredients, and is merely a plausibility argument.
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| ; in general{{anchor|in general (informal proof technique)}}: In a context not requiring rigor, this phrase often appears as a labor-saving device when the technical details of a complete argument would outweigh the conceptual benefits. The author gives a proof in a simple enough case that the computations are reasonable, and then indicates that "in general" the proof is similar.
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| ; morally true{{anchor|morally true}}: Used to indicate that the speaker believes a statement ''should'' be true, given their mathematical experience, even though a proof has not yet been put forward. As a variation, the statement may in fact be false, but instead provide a slogan for or illustration of a correct principle. [[Helmut Hasse|Hasse]]'s [[local-global principle]] is a particularly influential example of this.{{Citation needed|date=April 2010}}
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| ; [[trivial (mathematics)|trivial]]{{anchor|trivial}}: Similar to ''clearly''. A concept is trivial if it holds by definition, is immediately corollary to a known statement, or is a simple special case of a more general concept.
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| ==Notes==
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| <references/> | |
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| ==References==
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| *{{citation
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| | last2 = Mac Lane
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| | first2 = Saunders
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| | last1 = Eilenberg
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| | first1 = Samuel
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| | author2-link = Saunders Mac Lane
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| | author1-link = Samuel Eilenberg
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| | year = 1942
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| | title = Natural Isomorphisms in Group Theory
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| | journal = Proc. Natl. Acad. Sci. USA
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| | volume = 28
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| | pages = 537–543
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| | doi = 10.1073/pnas.28.12.537
| |
| }}.
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| * {{citation
| |
| | last = Impagliazzo
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| | first = Russell
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| | author-link = Russell Impagliazzo
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| | chapter = A personal view of average-case complexity
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| | year = 1995
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| | title = Proc. Tenth Annual Structure in Complexity Theory Conference (SCT'95)
| |
| | pages = 134–147
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| | doi = 10.1109/SCT.1995.514853
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| }}.
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| * {{citation
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| | first = Allyn
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| | year = 2004
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| | journal = AMS Notices
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| | volume = 51
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| | title = Comme Appelé du Néant — As If Summoned from the Void: The Life of Alexandre Grothendieck
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| | issue = 9,10
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| }} (Parts [http://www.ams.org/notices/200409/fea-grothendieck-part1.pdf I] and [http://www.ams.org/notices/200410/fea-grothendieck-part2.pdf II]).
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| *{{citation
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| | author1-link = Saunders Mac Lane
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| | title = The PNAS way back then
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| | year = 1997
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| | pages = 5983–5985
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| | volume = 94
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| | journal = Proc. Natl. Acad. Sci. USA
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| | url = http://www.pnas.org/cgi/reprint/94/12/5983.pdf
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| | doi = 10.1073/pnas.94.12.5983
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| | issue=12
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| }}.
| |
| *{{citation
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| | last = Mac Lane
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| | first = Saunders
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| | author-link = Saunders Mac Lane
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| | title = Categories for the Working Mathematician
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| | publisher = Springer
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| | year = 1998
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| }}.
| |
| *{{citation
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| | last1 = Monastyrsky
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| | first1 = Michael
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| | title = Some Trends in Modern Mathematics and the Fields Medal
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| | journal = Can. Math. Soc. Notes
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| | year = 2001
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| | volume = 33
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| | issue = 2 and 3
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| | url = http://www.fields.utoronto.ca/aboutus/FieldsMedal_Monastyrsky.pdf
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| }}.
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| *{{citation
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| | title = Infinitesimal methods for mathematical analysis
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| | editor1-last = Hoskins
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| | editor1-first = R.F.
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| | publisher = Horwood Publishing
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| | year = 2004
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| | page = 246
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| | url = http://books.google.com/?id=bLbfhYrhyJUC&pg=PA246
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| | isbn = 978-1-898563-99-0
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| }}.
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| *{{citation
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| | last1 = Poincare
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| | author1-link = Henri Poincaré
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| | title = The Foundations of Science
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| | year = 1913
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| | page = 435
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| | editor1-last = Halsted
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| | editor1-first = Bruce
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| | publisher = The Science Press
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| | url = http://books.google.com/?id=WxLJzL4e4wsC&printsec=titlepage
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| }}.
| |
| * {{citation
| |
| | last = Rota
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| | first = Gian-Carlo
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| | author-link = Gian-Carlo Rota
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| | title = The phenomenology of mathematical beauty
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| | year = 1977
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| | journal = Synthese
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| | volume = 111
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| | issue = 2
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| | pages = 171–182
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| | issn = 0039-7857
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| | doi = 10.1023/A:1004930722234
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| }}.
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| *{{citation
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| | last = Shafarevich
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| | first = Igor
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| | author-link = Igor Shafarevich
| |
| | year = 1991
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| | editor1-last = Kandall
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| | editor1-first = G.A.
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| | publisher = Springer
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| | title = Algebraic Geometry
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| | volume = IV
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| }}.
| |
| *{{citation
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| | title = The Seventeen Provers of the World
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| | editor-last = Wiedijk
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| | editor-first = Freek
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| | year = 2006
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| | publisher = Birkhäuser
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| | isbn = 3-540-30704-4
| |
| }}.
| |
| | |
| [[Category:Mathematical terminology| Jargon]]
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| [[Category:Glossaries of mathematics| ]]
| |