English
As above, the RingHom fst from R × S to R is surjective when R,S are semirings.
Русский
Как выше, отображение RingHom fst из R×S в R сюръективно при наличии полирин.
LaTeX
$$$\\text{RingHomSurjective }(\\text{fst } R S).$$$
Lean4
/-- Given semirings `R`, `S`, the natural projection homomorphism from `R × S` to `S`. -/
def snd : R × S →+* S :=
{ MonoidHom.snd R S, AddMonoidHom.snd R S with toFun := Prod.snd }