This tag is intended for questions concerning partial orders, equivalence relations, properties of relations (transitive, symmetric…), composition of relations and similar stuff. More-or-less the things about relations taught in the first elementary set theory or discrete math course.

A relation $R$ on a set $A$ is any subset of $A\times A$, i.e. any set of ordered pairs $(x,y)$ such that both $x$ and $y$ belong to $A$. Often we write $x\mathrel R y$ instead of $(x,y)\in R$. Typical examples are partial orders, e.g. the relation $\le$ on $\mathbb N$ and equivalence relation, e.g. the relation $=$ on $\mathbb N$.

This tag is intended for questions concerning partial orders, equivalence relations, properties of relations (transitive, symmetric…), composition of relations and similar topics taught in first elementary set theory or discrete mathematics courses.

For more information see e.g. Wikipedia article.

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