English
Another formulation: 0 ×ˢ t = 0.
Русский
Ещё одно формулирование: 0 ×ˢ t = 0.
LaTeX
$$$0 \times^{\mathrm{SProd}} t = 0$$$
Lean4
/-- `Multiset.sigma s t` is the dependent version of `Multiset.product`. It is the sum of
`(a, b)` as `a` ranges over `s` and `b` ranges over `t a`. -/
protected def sigma (s : Multiset α) (t : ∀ a, Multiset (σ a)) : Multiset (Σ a, σ a) :=
s.bind fun a => (t a).map <| Sigma.mk a