rfl
α : Type u
r : α → α → Prop
β : α → Type v
xs : KVChain (flip r) β
a : α
b : β a
ys : KVChain r β
hay : boundLeft a ys
⊢ List.predHead (fun a_1 => Sigma.relOnFst r a_1 { fst := a, snd := b }) xs.toList = boundLeft a xs
no goals