Section POrderTheory.
Context {disp : unit} {T : porderType disp}.
Implicit Types (x y : T) (s : seq T).
Definition lt_gtF x y hxy := le_gtF (@ltW x y hxy).
End Comparable3.

Lemma comparable_maxAC x y z : x >=< y -> x >=< z -> y >=< z ->
max (max x y) z = max (max x z) y.