English
For any z and pair xy, the antidiagonal membership of (−xy) is equivalent to the membership of xy; negating the pair does not change membership.
Русский
При любом z и паре xy, членство (−xy) в z.divisorsAntidiag эквивалентно членству xy; отрицание пары не влияет на принадлежность.
LaTeX
$$$ Iff\ ( -xy) \in z.divisorsAntidiag \iff xy \in z.divisorsAntidiag $$$
Lean4
theorem divisorsAntidiag_neg :
(-z).divisorsAntidiag = z.divisorsAntidiag.map (.prodMap (.refl _) (Equiv.neg _).toEmbedding) := by ext;
simp [mem_divisorsAntidiag, Prod.ext_iff, neg_eq_iff_eq_neg]