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