# How do I define a homomorphism of a graded commutative algebra?

I am working on implementing morphisms of graded commutative algebras. I have two graded commutative algebra, A with generators <w,x> and B with generators <y,z> . I define H the set of homomorphisms from A to B. Then, I want to define the homomorphisms f such that f(w)=y and f(x)=0 but I get an error:

sage: H = Hom(A,B) sage: H([y,0])

TypeError: images do not define a valid homomorphism

Please insert the code for $A,B$, so that we can reproduce the situation and the errors. Please use that button with

`101`

over`010`

(after B, and I, and the Link buttons...) to format properly the code. (Copy+paste the code, mark it, press that button or the combination Control+K on the selection.)Are you using the latest version of SageMath? In 8.4 some bugs just like this were fixed.