English
The product distributes over supremum on the right: M * (N ⊔ P) = M * N ⊔ M * P.
Русский
Произведение распределяется по верхнему объединению справа: M * (N ⊔ P) = M * N ⊔ M * P.
LaTeX
$$$ M * (N \sqcup P) = M * N \sqcup M * P $$$
Lean4
theorem sup_mul : (M ⊔ N) * P = M * P ⊔ N * P :=
le_antisymm
(mul_le.mpr fun mn hmn p hp ↦ by
obtain ⟨m, hm, n, hn, rfl⟩ := mem_sup.mp hmn
rw [right_distrib]; exact add_mem_sup (mul_mem_mul hm hp) <| mul_mem_mul hn hp)
(sup_le (mul_le_mul_left le_sup_left) <| mul_le_mul_left le_sup_right)