#8832: CombinatorialFreeModule doesn't properly coerce scalar during action
------------------------------+---------------------------------------------
Reporter: hivert | Owner: AlexGhitza
Type: defect | Status: new
Priority: major | Milestone: sage-4.4.1
Component: algebra | Keywords: CombinatorialFreeModule, action,
coercion
Author: Florent Hivert | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
------------------------------+---------------------------------------------
When a scalar has to be coerced to perform the action on a combinatorial
free module element, Sage refuse to perform the multiplication. As a
consequence, whereas the following is perfectly correct
{{{
sage: sage: P.<q> = QQ['q']
sage: F = FractionField(P)
sage: V = CombinatorialFreeModule(F, Words())
sage: w = Words()('abc')
sage: sage: ((1+q)/q)*V(w)
((q+1)/q)*B[word: abc]
}}}
this should also works
{{{
sage: (1+q)*V(w)
---------------------------------------------------------------------------
TypeError Traceback (most recent call
last)
...
TypeError: unsupported operand parent(s) for '*': 'Univariate Polynomial
Ring in q over Rational Field' and 'Free module generated by Words over
Fraction Field of Univariate Polynomial Ring in q over Rational Field'
}}}
The polynomial {{{1+q}}} should be coerced into its fraction field.
After the patch
{{{
sage: (1+q)*V(w)
(q+1)*B[word: abc]
}}}
Florent
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/8832>
Sage <http://www.sagemath.org>
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