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equivalence_relation [2013/05/23 17:19] nikolaj |
equivalence_relation [2013/09/04 17:27] nikolaj |
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===== Equivalence relation ===== | ===== Equivalence relation ===== | ||
==== Definition ==== | ==== Definition ==== | ||
- | | $X$ | | + | | @#88DDEE: $X$ | |
- | | $ \sim \in\text{Rel}(X) $ | | + | |
- | ^ $ \sim \in \text{EquivRel}(X) $ ^ | + | | @#FFBB00: $ \sim \in \text{EquivRel}(X) $ | |
- | The relation $R$ is an equivalence relation, if it's in the intersection of all reflexive, all symmetric and all transitive relation. Hence | + | | @#88DDEE: $ \sim \in \mathrm{Rel}(X) $ | |
+ | | $x,y,z\in X$ | | ||
- | ^ $ \forall_{\text{dom}(\sim)} x\ (\langle x,x\rangle \in \sim) $ ^ | + | | @#55EE55: $ x\sim x $ | |
- | ^ $ (\langle x,y\rangle \in \sim) \Leftrightarrow (\langle y,x\rangle \in \sim) $ ^ | + | | @#55EE55: $ x\sim y \Leftrightarrow y\sim x $ | |
- | ^ $ (\langle x,y\rangle \in \sim) \land (\langle y,z\rangle \in \sim) \Leftrightarrow (\langle x,z\rangle \in \sim) $ ^ | + | | @#55EE55: $ x\sim y \land y\sim z \Leftrightarrow x\sim z $ | |
- | ==== Ramifications ==== | + | ==== Discussion ==== |
+ | The relation $\sim$ is an equivalence relation, if it's in the intersection of all reflexive, all symmetric and all transitive relation. Hence | ||
=== Reference === | === Reference === | ||
Wikipedia: [[http://en.wikipedia.org/wiki/Equivalence_relation|Equivalence relation]] | Wikipedia: [[http://en.wikipedia.org/wiki/Equivalence_relation|Equivalence relation]] |