fact: Fixpoint left_sum_tree (X Y:Type) (p:WFT X) : WFT (X+Y) := match p with | ZT _ => SUP (fun x => SUP (fun y => SUP (fun z => ZT (X+Y)))) | SUP f => SUP (fun x => match x with | inl x0 => left_sum_tree Y (f x0) | inr x0 => SUP (fun y => match y with | inl y0 => left_sum_tree Y (f y0) | inr y0 => ZT (X+Y) end) end) end.
imports: Coq(Lia) AlmostFull.Default(AlmostFull)