a binary relation is an equivalence relation if R is reflexive: xRx is true for all x R is symmetric: x R y is true implies y R x is true R is transitive: for every x,y,z, xRy and y R z implies x R z
a binary relation is an equivalence relation if R is reflexive: xRx is true for all x R is symmetric: x R y is true implies y R x is true R is transitive: for every x,y,z, xRy and y R z implies x R z