Bitsv.sub1_lt: def of bend-collections-laws-crypto@1.0.0.0
Import: import bend-collections-laws-crypto@1.0.0.0/proofs/crypto/secp256k1/bitsv.bend as Bitsv
Lines 209-215 of bend-collections-laws-crypto@1.0.0.0/proofs/crypto/secp256k1/bitsv.bend: https://jend.leeeet.dev/read.txt?path=bend-collections-laws-crypto@1.0.0.0/proofs/crypto/secp256k1/bitsv.bend&start_line=209&end_line=215

import Base
import bend-collections-laws-crypto@1.0.0.0/proofs/math/natural/arith.bend as NR

def sub1_lt(b: Nat) -> {Nat.is_lt(Nat.sub(1n, b), 2n) == True{} : Bool}:
  match b:
    case 0n:
      {==}
    case 1n+k:
      %Equal.sym(Nat, Nat.sub(0n, k), 0n, NR.zsub(k)) : {Nat.is_lt(_, 2n) == True{} : Bool}
      {==}

Uses (6):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Bool
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Equal.sym
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat.is_lt
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat.sub
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-crypto@1.0.0.0/proofs/math/natural/arith.bend&name=zsub