Or in Y1of3, Y2of3, Y3of3 form:
let Yv = \ff. Y (\v g h. ff ( v g h) g h) in
Or in Y1of3, Y2of3, Y3of3 form:
let Yv = \ff. Y (\v g h. ff ( v g h) g h) in
let g = Y2of3 (\f g h. A) (\f g h. B) (\f g h. C) in
let h = Y3of3 (\f g h. A) (\f g h. B) (\f g h. C) in
D
let g = Y2of3 (\f g h. A) (\f g h. B) (\f g h. C) in
let h = Y3of3 (\f g h. A) (\f g h. B) (\f g h. C) in
D