Instance forAllMonotonic {A C} {_ : Checkable C} `{Show A} (g : G A) (f : A -> C)
        `{SizeMonotonic _ g} `{forall x, SizeMonotonicChecker (checker (f x))} :
  SizeMonotonicChecker (forAll g f).

Lemma semForAllShrinkSize: forall {A C} `{Checkable C} `{Show A} (gen : G A) (f : A -> C) shrinker (size: nat), semCheckerSize (forAllShrink gen shrinker f) size <-> forall a : A, semGenSize gen size a -> semCheckableSize (f a) size.