Definition bobby_eight_poly x := length (functions_of_prog prog) * Nat.pow x max_arity.

(* lemma 64 *)
Lemma bobby_eight i s p c1 f lt c2 v:
let proof_tree := cbv_update i s p c1 (fapply f lt) c2 v in
PPO_prog -> wf proof_tree ->
length (activations_at_rank (rank f) proof_tree) <=
bobby_eight_poly (term_size (proj_left proof_tree)).