From Undecidability.Shared.Libs.PSL Require Import Prelim.
From Undecidability.Shared.Libs.PSL Require Import EqDec.
(* ** Numbers **)
Instance nat_le_dec (x y : nat) : dec (x <= y) :=
le_dec x y.

Lemma size_recursion (X : Type) (sigma : X -> nat) (p : X -> Type) :
(forall x, (forall y, sigma y < sigma x -> p y) -> p x) ->
forall x, p x.