A linear order (or total order) on a set is a relation on that is:

  1. irreflexive
  2. transitive
  3. trichotomous We say is linearly ordered by , or simply is a linearly ordered set.

Notation

For write for and for ” or ” This satisfies:

  1. reflexivity
  2. antisymmetric:
  3. transitive:
  4. trichotomous: