English
If h: a ∨ b ∨ c, and ha: a → d, hb: b → d, hc: c → d, then d.
Русский
Если h: a ∨ b ∨ c, ha: a → d, hb: b → d, hc: c → d, тогда d.
LaTeX
$${c d : Prop} (h : a \\lor (b \\lor c)) (ha : a \\to d) (hb : b \\to d) (hc : c \\to d) : d$$
Lean4
theorem elim3 {c d : Prop} (h : a ∨ b ∨ c) (ha : a → d) (hb : b → d) (hc : c → d) : d :=
Or.elim h ha fun h₂ ↦ Or.elim h₂ hb hc