i(one()) -> one()
i(i(x)) -> x
mult(one(),x) -> x
mult(x,one()) -> x
mult(mult(x,y),z) -> mult(x,mult(y,z))
d(x,y) -> mult(x,i(y))
mult(i(x),x) -> one()
mult(x,i(x)) -> one()
i(mult(y,x)) -> mult(i(x),i(y))
mult(i(x),mult(x,y)) -> y
mult(x,mult(i(x),y)) -> y