def AP.le_succ
import bend-osdev-array@0.1.0.1/PROOF.bend as PROOFimport Base
70def AP.le_succ(y: Nat, x: Nat) -> {Nat.is_le(1n+y, x) == Nat.is_lt(y, x) : Bool}:
71 match y x:
72 case 0n 0n:
73 {==}
74 case 0n 1n+p:
75 match p:
76 case 0n:
77 {==}
78 case 1n+q:
79 {==}
80 case 1n+q 0n:
81 {==}
82 case 1n+q 1n+p:
83 AP.le_succ(q, p)