Set Implicit Arguments.
Require qs_definitions.
Require qs_parts.
Require U.
Section contents.
Variables (ee: E) (ol: list ee).

Lemma pair_eq_inv (X Y: Set) (x x': X) (y y': Y): (x, y) = (x', y') -> x' = x /\ y' = y.
Let qs := @U.qs ee ol.