fact: Definition Formula_depth_ind : forall P : Formula -> Prop, (forall a : Formula, (forall b : Formula, lt_depth b a -> P b) -> P a) -> forall a : Formula, P a.
imports: Coq(Lists.List Ensembles Peano_dec Eqdep_dec Arith Compare_dec Utf8) hydras(Ackermann.misc Compat815 )