Partial Orders

If for each x in D we have x R x, then R is reflexive.

If for each x in D and y in D we have

x R y and y R x imply x = y,

then R is antisymmetric.

If for each x in D, y in D, and z in D we have

x R y and y R z imply x R z,

then R is transitive.

If R has all 3 properites, R is a partial order.