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

asked 2018-10-29 10:26:05 +0200

Belén gravatar image

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

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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.)

dan_fulea gravatar imagedan_fulea ( 2018-10-29 14:41:29 +0200 )edit

Are you using the latest version of SageMath? In 8.4 some bugs just like this were fixed.

rburing gravatar imagerburing ( 2018-10-29 19:02:02 +0200 )edit

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answered 2018-10-30 21:44:39 +0200

See for an almost identical question. As @rburing points out, this has been fixed in recent versions of Sage: see

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Asked: 2018-10-29 10:26:05 +0200

Seen: 251 times

Last updated: Oct 30 '18