#8992: Coercion of univariate quotient polynomial rings
-------------------------+--------------------------------------------------
Reporter: SimonKing | Owner: robertwb
Type: defect | Status: new
Priority: major | Milestone: sage-4.4.2
Component: coercion | Keywords: coercion quotient ring
Author: | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
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Comment(by SimonKing):
I think I found one source of the problem. The call method (that will
become an element_constructor method) says:
{{{
if isinstance(x, PolynomialQuotientRingElement):
P = x.parent()
if P is self:
return x
elif P == self:
return PolynomialQuotientRingElement(self,
self.__ring(x.lift()), check=False)
}}}
In other words: ''Only'' if the parent of x is equal to self, it is
attempted to convert x into self via conversion in the polynomial ring. I
think this condition should simply be dropped.
Furthermore, after the above code block
{{{
return PolynomialQuotientRingElement(self, self.__ring(x) ,
check=True)
}}}
Hence, it is again tried to interprete x in the polynomial ring of self.
But the problem is that the variable names in self and in
{{{self.__ring}}} are usually different. So, conversion of strings must
fail.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/8992#comment:2>
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