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