reflexivity.
Qed.

Theorem findCollision_1_correct :
forall (A B : Set) eqd1 eqd2 (ls : list (A * B)) (x1 x2 : A) y,
findCollision_1 eqd1 eqd2 ls x1 y =
Some x2 ->
x1 <> x2 /\
In (x2, y) ls.