law add_sub_add_left_sym

bend-mathlib@0.8.1.0 · nat.bend:4521

import Base

4521# A common left summand cancels in a difference: (k + n) - (k + m) = n - m, reversed to rewrite toward the simple side.
4522law add_sub_add_left_sym:
4523  for k: Nat
4524  for -n: Nat
4525  for -m: Nat
4526  {Nat.sub(n, m) == Nat.sub(Nat.add(k, n), Nat.add(k, m)) : Nat}