EDB — 06J

Exercises

1. [06J](Proposed on 2022-12) Let \(X\) be a non-empty set and \(R⊆ X^ 2\) an order relation, then there is a total order \(T\) that extends \(R\) (i.e. \(R⊆ T\), considering relations as subsets of \(X^ 2\)).