def nat.le_succ
import bend-osdev-algo@0.1.0.0/PROOF.bend as PROOFimport Base
98def nat.le_succ(a: Nat, b: Nat, e: {Nat.is_le(a, b) == True{} : Bool}) -> {Nat.is_le(a, 1n+b) == True{} : Bool}:
99 match a b:
100 case 0n _:
101 {==}
102 case 1n+ap 0n:
103 Empty.absurd({Nat.is_le(1n+ap, 1n) == True{} : Bool}, absurd.ft(e))
104 case 1n+ap 1n+bp:
105 nat.le_succ(ap, bp, e)