#19257: pushout wrong when using coercion_reversed in construction functor
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Reporter: dkrenn | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-6.9
Component: categories | Keywords:
Merged in: | Authors:
Reviewers: | Report Upstream: N/A
Work issues: | Branch:
Commit: | Dependencies:
Stopgaps: |
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In `sage.categories.pushout.SubspaceFunctor` we have the example
{{{
sage: M = ZZ^3
sage: S = M.submodule([(1,2,3),(4,5,6)]); S
Free module of degree 3 and rank 2 over Integer Ring
Echelon basis matrix:
[1 2 3]
[0 3 6]
sage: S.construction()
(SubspaceFunctor,
Ambient free module of rank 3 over the principal ideal domain Integer
Ring)
}}}
The subspace functor uses `coercion_reversed=True`. The pushout
sage: sage.categories.pushout.pushout(S, M)
Ambient free module of rank 3 over the principal ideal domain Integer Ring
}}}
is wrong; it should be `ZZ^3`. Consequently
{{{
sage: cm = sage.structure.element.get_coercion_model()
sage: cm.common_parent(S, M)
Ambient free module of rank 3 over the principal ideal domain Integer Ring
}}}
also gives the wrong result.
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Ticket URL: <http://trac.sagemath.org/ticket/19257>
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