Nat.mul_mul_mul_comm: law of bend-mathlib@0.8.1.0
Import: import bend-mathlib@0.8.1.0/nat.bend as Nat
Lines 2174-2180 of bend-mathlib@0.8.1.0/nat.bend: https://jend.leeeet.dev/read.txt?path=bend-mathlib@0.8.1.0/nat.bend&start_line=2174&end_line=2180

import Base

# Four-way regrouping of a product: (a * b) * (c * d) = (a * c) * (b * d).
law mul_mul_mul_comm:
  for a: Nat
  for b: Nat
  for c: Nat
  for d: Nat
  {Nat.mul(Nat.mul(a, b), Nat.mul(c, d)) == Nat.mul(Nat.mul(a, c), Nat.mul(b, d)) : Nat}

Uses (5):
  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.mul
  https://jend.leeeet.dev/definition.txt?path=bend-mathlib@0.8.1.0/nat.bend&name=mul_assoc
  https://jend.leeeet.dev/definition.txt?path=bend-mathlib@0.8.1.0/nat.bend&name=mul_left_comm