Program Instance unsizedMonotonicChecker (c : Checker) `{UnsizedChecker c} : 
  SizeMonotonicChecker c.

Lemma semShrinking_idSize {C A} {HCheck : Checkable C} (sh : A -> list A) (x : A) (pf : A -> C) (s : nat) : semCheckerSize (shrinking sh x pf) s <-> semCheckableSize (pf x) s.