The following code throws a ValueError("The given dictionary does not determine a valid differential"):
A.<x, y, z> = GradedCommutativeAlgebra(QQ, degrees=(2, 3, 4))
AQ = A.quotient(A.ideal(x^3))
E = AQ.cdg_algebra({y: x^2, z: x*y})
It seems the cause is a check if not self(self(i)).is_zero(). Since the error disappears on omitting the z = x*y differential, I presume it's evaluating $d(xy) = x^3$ to be something non-zero, maybe because it is being evaluated in A and not AQ. Is this a bug or am I supposed to define this CDGA in a different way?
