(** * Some properties of [cond] *)

Lemma map_sem_repeat :
forall fl vnl vsl n s,
(forall f, In f fl -> arities f = ok_arities n s) ->
map (fun f => sem f vnl vsl) fl =
map (
fun f =>
sem f
(vnl ++ repeat (n - length vnl) nil)
(vsl ++ repeat (s - length vsl) nil)
) fl.