law u32_sub_exact_sym

bend-mathlib@0.8.1.0 · u32.bend:1182

import Base
import bend-mathlib@0.8.1.0/nat.bend as MNat

1182# U32 subtraction is exact without underflow: b <= a implies to_nat (a - b) = a - b, reversed to rewrite toward the simple side.
1183law u32_sub_exact_sym:
1184  for a: U32
1185  for b: U32
1186  for h: MNat.le(U32.to_nat(b), U32.to_nat(a))
1187  {Nat.sub(U32.to_nat(a), U32.to_nat(b)) == U32.to_nat(U32.sub(a, b)) : Nat}