Set-Theory

Binary Relation

Math Set-Theory

A binary relation R over sets X and Y is a subset of the cartesian product of X×Y. Where X is the domain, or set of departure of R, and Y is the codomain, or set of destination of R. An element x∈X is related to y∈Y, iff the ordered pair (x,y) is found within the (above) subset.

Bijective Function

Math Set-Theory Real-Analysis

A function is bijective or “invertible” if it is Both one-to-one and onto (injective and surjective) In other words: each element of one set is paired with exactly one element of the other set, and vice versa