Admitted. (* QuickChick bexp_eval_false. *)

Theorem hoare_if : forall P Q b c1 c2,
{{fun st => P st /\ bassn b st}} c1 {{Q}} ->
{{fun st => P st /\ ~(bassn b st)}} c2 {{Q}} ->
{{P}} (IFB b THEN c1 ELSE c2 FI) {{Q}}.