$! simple.constants.1/3
D y (x C a) (x b C)
C y (x C a) (x @ C)
C y (x @ @) (x b C)

$! simple.constants.1/1
D y (x (y C))
C y (x @)

$! simple.constants.1/1'
D y (z. x (y C))
C y (z. x z)

$! simple.constants.1/2
D y (x (y C (x C)))
C y (x (y C @))


$! simple.constants.1/4
D y (x C a) (x b C) (y C c)
C y (x C a) (x @ C) (y C c)
C y (x @ @) (x b C) (y C c)
C y (x C a) (x b C) (y C @)