fact: Definition req_cond G := forall x : G, ~~ leaf x -> forall D, D \in Req (label x) -> exists2 y, edge x y & suppC (label y) D.
imports: mathcomp.ssreflect.ssreflect mathcomp(all_ssreflect) CompDecModal.libs(edone bcase fset base sltype) CompDecModal.CTL(CTL_def dags)