#12924: SchubertPolynomialRing causes symmetrica and Sage to crash on bad input
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Reporter: VivianePons | Owner: VivianePons
Type: defect | Status: needs_review
Priority: major | Milestone: sage-5.1
Component: combinatorics | Resolution:
Keywords: days38, Schubert polynomials | Work issues:
Report Upstream: N/A | Reviewers:
Authors: Viviane Pons | Merged in:
Dependencies: | Stopgaps:
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Changes (by {'newvalue': u'Viviane Pons', 'oldvalue': ''}):
* status: new => needs_review
* author: => Viviane Pons
Old description:
> The SchubertPolynomialRing expects a permutation as an index. When a list
> is given which is not a permutation, the object is created anyway. The
> problem comes when one tries to expand the polynomial, if the index is
> not a valid permutation, it makes symmetrica crash which makes Sage crash
> !
>
> {{{
> sage: S = SchubertPolynomialRing(ZZ)
> sage: pol = S([2,1,3])
> sage: pol.expand()
> x0
> sage: pol = S([2,1,1])
> sage: pol.expand()
> function: mult_apply_integer(2)
> python: function: mult_apply_integer(2)
> : Operation not permitted
> }}}
> So the idea would be to check when the polynomial is created that the
> input is correct and raise an exception at this point if it's not. [[BR]]
New description:
The SchubertPolynomialRing expects a permutation as an index. When a list
is given which is not a permutation, the object is created anyway. The
problem comes when one tries to expand the polynomial, if the index is not
a valid permutation, it makes symmetrica crash which makes Sage crash !
{{{
sage: S = SchubertPolynomialRing(ZZ)
sage: pol = S([2,1,3])
sage: pol.expand()
x0
sage: pol = S([2,1,1])
sage: pol.expand()
function: mult_apply_integer(2)
python: function: mult_apply_integer(2)
: Operation not permitted
}}}
So the idea would be to check when the polynomial is created that the
input is correct and raise an exception at this point if it's not.
New behaviour is now :
{{{
sage: X = SchubertPolynomialRing(QQ)
sage: X._element_constructor_([1,2,1])
Traceback (most recent call last):
...
ValueError: The input [1, 2, 1] is not a valid permutation
sage: X._element_constructor_(Permutation([1,2,1]))
Traceback (most recent call last):
...
ValueError: The input [1, 2, 1] is not a valid permutation
}}}
Tests have been added into the documentation.
--
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12924#comment:1>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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