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		<title>imported&gt;Linkhyrule5: Explained &quot;realizable&quot;.</title>
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		<summary type="html">&lt;p&gt;Explained &amp;quot;realizable&amp;quot;.&lt;/p&gt;
&lt;p&gt;&lt;b&gt;New page&lt;/b&gt;&lt;/p&gt;&lt;div&gt;{{short description|Describes the objects of a given type, up to some equivalence}}&lt;br /&gt;
{{Unreferenced|date=December 2009}}&lt;br /&gt;
In [[mathematics]], a &amp;#039;&amp;#039;&amp;#039;classification theorem&amp;#039;&amp;#039;&amp;#039; answers the [[classification]] problem: &amp;quot;What are the objects of a given type, up to some [[Equivalence relation|equivalence]]?&amp;quot;. It gives a non-redundant [[enumeration]]: each object is equivalent to exactly one class.&lt;br /&gt;
&lt;br /&gt;
A few issues related to classification are the following.&lt;br /&gt;
&lt;br /&gt;
*The equivalence problem is &amp;quot;given two objects, determine if they are equivalent&amp;quot;.&lt;br /&gt;
*A [[complete set of invariants]], together with which invariants are realizable, solves the classification problem, and is often a step in solving it. (A combination of invariant values is realizable if there in fact exists an object whose invariants take on the specified set of values)&lt;br /&gt;
*A {{clarify span|computable complete set of invariants|reason=Shouldn&amp;#039;t this be &amp;quot;finite set of computable invariants&amp;quot;? Computability (whatever this is supposed to mean on a set of functions) is of no help if infinitely many functions must be evaluated or if an uncomputable function must be evaluated.|date=October 2020}} (together with which invariants are realizable) solves both the classification problem and the equivalence problem.&lt;br /&gt;
* A [[canonical form]] solves the classification problem, and is more data: it not only classifies every class, but provides a distinguished (canonical) element of each class.&lt;br /&gt;
&lt;br /&gt;
There exist many &amp;#039;&amp;#039;&amp;#039;classification theorems&amp;#039;&amp;#039;&amp;#039; in [[mathematics]], as described below.&lt;br /&gt;
&lt;br /&gt;
==Geometry==&lt;br /&gt;
* {{annotated link|Euclidean plane isometry#Classification of Euclidean plane isometries|Classification of Euclidean plane isometries}}&lt;br /&gt;
* [[Platonic solid#Classification|Classification of Platonic solids]]&lt;br /&gt;
* Classification theorems of surfaces&lt;br /&gt;
** {{annotated link|Classification of two-dimensional closed manifolds}}&lt;br /&gt;
** {{annotated link|Enriques–Kodaira classification}} of [[algebraic surfaces]] (complex dimension two, real dimension four)&lt;br /&gt;
** {{annotated link|Nielsen–Thurston classification}} which characterizes homeomorphisms of a compact surface&lt;br /&gt;
* Thurston&amp;#039;s eight model geometries, and the {{annotated link|geometrization conjecture}}&lt;br /&gt;
* {{annotated link|Holonomy#The Berger classification|Berger classification}}&lt;br /&gt;
* {{annotated link|Symmetric space#Classification result|Classification of Riemannian symmetric spaces}}&lt;br /&gt;
* {{annotated link|Lens space#Classification of 3-dimensional lens spaces|Classification of 3-dimensional lens spaces}}&lt;br /&gt;
* {{annotated link|Classification of manifolds}}&lt;br /&gt;
&lt;br /&gt;
==Algebra==&lt;br /&gt;
* {{annotated link|Classification of finite simple groups}}&lt;br /&gt;
** {{annotated link|Abelian group#Classification|Classification of Abelian groups}}&lt;br /&gt;
** {{annotated link|Finitely generated abelian group#Classification|Classification of Finitely generated abelian group}}&lt;br /&gt;
** {{annotated link|Multiple transitivity|Classification of Rank 3 permutation group}}&lt;br /&gt;
** {{annotated link|Rank 3 permutation group#Classification|Classification of 2-transitive permutation groups}}&lt;br /&gt;
* {{annotated link|Artin–Wedderburn theorem}} &amp;amp;mdash; a classification theorem for semisimple rings&lt;br /&gt;
* {{annotated link|Classification of Clifford algebras}}&lt;br /&gt;
* {{annotated link|Classification of low-dimensional real Lie algebras}}&lt;br /&gt;
* Classification of Simple Lie algebras and groups&lt;br /&gt;
** {{annotated link|Semisimple Lie algebra#Classification|Classification of simple complex Lie algebras}}&lt;br /&gt;
** {{annotated link|Satake diagram|Classification of simple real Lie algebras}}&lt;br /&gt;
** {{annotated link|Simple Lie group#Full classification|Classification of centerless simple Lie groups}}&lt;br /&gt;
** {{annotated link|List of simple Lie groups|Classification of simple Lie groups}}&lt;br /&gt;
* {{annotated link|Bianchi classification}}&lt;br /&gt;
* {{annotated link|ADE classification}}&lt;br /&gt;
*{{annotated link|Langlands classification}}&lt;br /&gt;
&lt;br /&gt;
==Linear algebra==&lt;br /&gt;
* {{annotated link|Finite-dimensional vector space}}s (by dimension)&lt;br /&gt;
* {{annotated link|Rank–nullity theorem}} (by rank and nullity)&lt;br /&gt;
* {{annotated link|Structure theorem for finitely generated modules over a principal ideal domain}}&lt;br /&gt;
* {{annotated link|Jordan normal form}}&lt;br /&gt;
* {{annotated link|Frobenius normal form}} (rational canonical form)&lt;br /&gt;
* {{annotated link|Sylvester&amp;#039;s law of inertia}}&lt;br /&gt;
&lt;br /&gt;
==Analysis==&lt;br /&gt;
* {{annotated link|Classification of discontinuities}}&lt;br /&gt;
&lt;br /&gt;
==Dynamical systems==&lt;br /&gt;
* {{annotated link|Classification of Fatou components}}&lt;br /&gt;
* [[Ratner&amp;#039;s theorems#Short description|Ratner classification theorem]]&lt;br /&gt;
&lt;br /&gt;
==Mathematical physics==&lt;br /&gt;
* {{annotated link|Classification of electromagnetic fields}}&lt;br /&gt;
* {{annotated link|Petrov classification}}&lt;br /&gt;
* {{annotated link|Segre classification}}&lt;br /&gt;
* {{annotated link|Wigner&amp;#039;s classification}}&lt;br /&gt;
&lt;br /&gt;
==See also==&lt;br /&gt;
* {{annotated link|Representation theorem}}&lt;br /&gt;
* {{annotated link|Comparison theorem}}&lt;br /&gt;
* {{annotated link|List of manifolds}}&lt;br /&gt;
* [[List of theorems]]&lt;br /&gt;
&lt;br /&gt;
==References==&lt;br /&gt;
{{reflist}}&lt;br /&gt;
&lt;br /&gt;
{{DEFAULTSORT:Classification Theorem}}&lt;br /&gt;
[[Category:Mathematical theorems]]&lt;br /&gt;
[[Category:Mathematical classification systems]]&lt;/div&gt;</summary>
		<author><name>imported&gt;Linkhyrule5</name></author>
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