English
Let f: X → Z and g: Y → Z. The map Sum.elim f g: X ⊕ Y → Z is continuous iff f and g are continuous.
Русский
Пусть f: X → Z и g: Y → Z. Отображение Sum.elim f g: X ⊕ Y → Z непрерывно тогда и только тогда, когда f и g непрерывны.
LaTeX
$$$\\\\operatorname{Continuous}(\\\\mathrm{Sum.elim}(f,g)) \\\\iff \\\\operatorname{Continuous}(f) \land \\\\operatorname{Continuous}(g).$$$
Lean4
theorem continuous_sumElim {f : X → Z} {g : Y → Z} : Continuous (Sum.elim f g) ↔ Continuous f ∧ Continuous g :=
continuous_sum_dom