> For the complete documentation index, see [llms.txt](https://mandober.gitbook.io/math-debrief/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://mandober.gitbook.io/math-debrief/220-relation-theory/terms/relation-general.md). # Relation The term *relation* most often refers to a binary relation, although ternary or, generally, n-ary relations are also encountered. A *finitary relation* or *n-ary relation* is a set of n-tuples. Specific types of relations include: * Binary relation (or correspondence, dyadic relation, or 2-place relation) * Equivalence relation (reflexive + symmetic + transitive relation) * Heterogeneous relation, a relation between possibly distinct sets * Reflexive relation * Serial relation * Ternary relation (or triadic, 3-adic, 3-ary, 3-dimensional, or 3-place relation) Relation may also refer to: * Directed relation * Relation algebra, an algebraic structure inspired by algebraic logic