English
If α is a CommSemiring, then WithTop α is a CommSemiring as well.
Русский
Если α — коммутативное полугруппой кольцо (CommSemiring), то WithTop α тоже CommSemiring.
LaTeX
$$$\\\\mathrm{WithTop} \\alpha \\\\text{ is a CommSemiring if } \\alpha \\\\text{ is}$$$
Lean4
instance instCommSemiring [CommSemiring α] [PartialOrder α] [CanonicallyOrderedAdd α] [NoZeroDivisors α]
[Nontrivial α] : CommSemiring (WithTop α)
where
toSemiring := WithTop.instSemiring
__ := WithTop.instCommMonoidWithZero