Math 2.0

Mathematical logic and foundations Definition

Binary relation

Builds on Cartesian productSubset

Definition

Let AA and BB be sets. A binary relation from AA to BB is a subset RR of the Cartesian product A×BA \times B. For a∈Aa \in A and b∈Bb \in B, write aRba \mathrel{R} b when (a,b)∈R(a, b) \in R. A binary relation on AA is a binary relation from AA to AA.

Remarks

Examples on ℤ\mathbb{Z} are ≤\le, == and divisibility ∣\mid. A relation on a finite set can be drawn as a directed graph, with an arrow from aa to bb when aRba \mathrel{R} b. A function is a special kind of binary relation.

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  1. Element definition
  2. Proposition concept
  3. Set definition
  4. Implication definition
  5. Predicate definition
  6. Ordered pair definition
  7. Universal quantifier definition
  8. Cartesian product definition
  9. Subset definition
  10. Binary relation definition

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Further reading

  1. Web https://en.wikipedia.org/wiki/Binary_relation, lead section
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MSC03E20
DefinesBinary relation
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