English
If α is a Monoid, then Filter α is a Monoid under pointwise multiplication.
Русский
Если α — моноид, то Filter α образует моноид под точечным умножением.
LaTeX
$$$\mathrm{Filter}(\alpha)$ is a Monoid when $\alpha$ is a Monoid.$$
Lean4
/-- `Filter α` is a `Monoid` under pointwise operations if `α` is. -/
@[to_additive /-- `Filter α` is an `AddMonoid` under pointwise operations if `α` is. -/
]
protected def monoid : Monoid (Filter α) :=
{ Filter.mulOneClass, Filter.semigroup, @Filter.instNPow α _ _ with }