English
For R,S with multiplications, IsLeftRegular (a,b) holds iff IsLeftRegular a and IsLeftRegular b.
Русский
Для пар (a,b) в пределах R × S верно: IsLeftRegular (a,b) ⇔ IsLeftRegular a ∧ IsLeftRegular b.
LaTeX
$$IsLeftRegular( { fst := a, snd := b } ) \iff IsLeftRegular a ∧ IsLeftRegular b$$
Lean4
@[to_additive (attr := simp)]
theorem isLeftRegular_mk {a : R} {b : S} : IsLeftRegular (a, b) ↔ IsLeftRegular a ∧ IsLeftRegular b :=
have : Nonempty R := ⟨a⟩;
have : Nonempty S := ⟨b⟩;
Prod.map_injective