English
The left-option comparison between mulOption terms corresponds exactly to a P1 condition on the corresponding moves.
Русский
Сравнение левых вариантов mulOption точно соответствует условию P1 на соответствующие ходы.
LaTeX
$$$\\forall {x_1 x_2 y} \\ hx \\ IH24 x_1 x_2 y \\to (\\forall i \\in x_1.LeftMoves)(\\forall k \\in y.LeftMoves), \\,(\\mathrm{lt}(Quotient.mk s (x_1.mulOption y i k)) (Quotient.mk s (instHMul.hMul x_2 y)))$$
Lean4
theorem mulOption_lt_iff_P1 {i j k l} :
(⟦mulOption x y i k⟧ : Game) < -⟦mulOption x (-y) j l⟧ ↔
P1 (x.moveLeft i) x (x.moveLeft j) y (y.moveLeft k) (-(-y).moveLeft l) :=
by
dsimp only [P1, mulOption, quot_sub, quot_add]
simp_rw [neg_sub', neg_add, quot_mul_neg, neg_neg]