proposition: Lemma succ_le_succ (a b : mynat) (h : a ≤ b) : succ a ≤ succ b.
proof: Proof. destruct h as [c h]. exists c. rewrite succ_add. rewrite succ_eq_succ_iff. exact h. Qed.
imports: Unicode.Utf8 Game.Mynat.Definition Game.Mynat.Add Game.Mynat.Mul Game.Mynat.Le Game.World.Addition Game.World.Multiplication Game.World.Proposition Game.World.AdvancedProposition Game.World.AdvancedAddition Game.World.AdvancedMultiplication