subquotient of module
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)
True
Replacing 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.