}.
notation "a break # b" non associative with precedence 50 for @{ 'apart $a $b}.
-interpretation "axiomatic apartness" 'apart x y =
+interpretation "apartness" 'apart x y =
(cic:/matita/excedence/ap_apart.con _ x y).
definition strong_ext ≝ λA:apartness.λop:A→A.∀x,y. op x # op y → x # y.