MAYBE

Problem:
 rev(nil()) -> nil()
 rev(rev(x)) -> x
 rev(++(x,y)) -> ++(rev(y),rev(x))
 ++(nil(),y) -> y
 ++(x,nil()) -> x
 ++(.(x,y),z) -> .(x,++(y,z))
 ++(x,++(y,z)) -> ++(++(x,y),z)
 make(x) -> .(x,nil())

Proof:
 Open