proposition: Lemma Zright_child_unfold: forall i, Zright_child i = Zleft_child i + 1.
proof: Proof. unfold Zright_child, Zleft_child, binary_heap_model.right_child. intros. rewrite Nat2Z.inj_add. trivial. Qed.
imports: VST.floyd.proofauto CertiGraph.binheap.binary_heap_model