English
The collection of a with nonempty SMulAntidiagonal hs ht a is IsPWO.
Русский
Множество a с непустым SMulAntidiagonal hs ht a обладает свойством IsPWO.
LaTeX
$${a | (SMulAntidiagonal hs ht a).Nonempty}.IsPWO$$
Lean4
/-- `s.sigma t` is the finset of dependent pairs `⟨i, a⟩` such that `i ∈ s` and `a ∈ t i`. -/
protected def sigma : Finset (Σ i, α i) :=
⟨_, s.nodup.sigma fun i => (t i).nodup⟩