(* Evaluation of a reified formula *)

(* Specifications: *)
Lemma same_env_sym e e' : same_env e e' -> same_env e' e.
(* Evaluation and substitution by a constant *)
Lemma holds_fsubst e f i v :
holds e (fsubst f (i, v%:T)%T) <-> holds (set_nth 0 e i v) f.