Definition 5.41 (Total)

A relation R on a set A is called total if all a,b∈A satisfy: (a,b)∈R or (b,a)∈R

Tip

This can be formalised in predicate logic by

∀x∀y((x,y)∈R∨(y,x)∈R)

Where the domain is the set of all elements in A