 | 1 | initial version |
how can I take a quotient of a submodule? I was expecting the following to work:
sage: M = CombinatorialFreeModule(QQ, [1,2], prefix='x'); x = M.basis()
sage: A = M.submodule([x[2]])
sage: A.quotient_module(A)
Free module generated by {1} over Rational Field
Which is clearly taking the quotient over the ambient space of A and not the image
sage: A.quotient_module(A) == M.quotient_module(A)
TrueReplacing A with A.lift.image() is the same.
how can I take a quotient of a submodule? I was expecting the following to work:
sage: M = CombinatorialFreeModule(QQ, [1,2], prefix='x'); x = M.basis()
sage: A = M.submodule([x[2]])
sage: A.quotient_module(A)
Free module generated by {1} over Rational Field
Which is clearly taking the quotient over the ambient space of A and not the image
sage: A.quotient_module(A) == M.quotient_module(A)
TrueReplacing A with A.lift.image() is the same.
EDIT: well, reading now in Modules.WithBasis.FiniteDimensional.ParentMethods.quotient_modules this is simply a call to QuotientModuleWithBasis(A,category) which will infer the parent of A.
As a side observation, I find it disturbing that there is not even a check that submodule is indeed a submodule of self in that call.
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