In mathematics, a classification theorem answers the classification problem: "What are the objects of a given type, up to some equivalence?". It gives a non-redundant enumeration: each object is equivalent to exactly one class.

A few issues related to classification are the following.

  • The equivalence problem is "given two objects, determine if they are equivalent".
  • 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)
  • A computable complete set of invariants[clarify] (together with which invariants are realizable) solves both the classification problem and the equivalence problem.
  • 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.

There exist many classification theorems in mathematics, as described below.

Geometry

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Algebra

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Linear algebra

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Analysis

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Dynamical systems

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Mathematical physics

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See also

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References

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