proposition: Lemma prune_D1 : D1 (prune pcond S0).
proof: Proof. move => C /pruneE. rewrite negbK. move/allP => H p s Hs. exact: (H ([p]s^-) Hs). Qed.
imports: Relations Classical_Pred_Type mathcomp.ssreflect.ssreflect mathcomp(all_ssreflect) CompDecModal.libs(edone bcase fset base) CompDecModal.PDL(PDL_def)