#14025: Comparison of elements of the quotient group of a FreeGroup
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Reporter: ppurka | Owner: joyner
Type: defect | Status: new
Priority: major | Milestone: sage-wishlist
Component: group theory | Resolution:
Keywords: | Work issues:
Report Upstream: N/A | Reviewers:
Authors: | Merged in:
Dependencies: #12339 | Stopgaps:
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Description changed by ppurka:
Old description:
> The following never finishes.
> {{{
> F.<x,y> = FreeGroup()
> H = F.quotient([x^2*y^-3])
> L = H(y*x)
> R = H(x*y)
> L == R
> }}}
New description:
The following never finishes.
{{{
F.<x,y> = FreeGroup()
H = F.quotient([x^2*y^-3])
L = H(y*x)
R = H(x*y)
L == R
}}}
Another example with a segmentation fault.
{{{
F.<x,y> = FreeGroup()
r = x^2*y^-3
H = F.quotient([r])
H(r) == H.one_element()
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "_sage_input_3.py", line 10, in <module>
exec compile(u'open("___code___.py","w").write("# -*- coding: utf-8
-*-\\n" +
_support_.preparse_worksheet_cell(base64.b64decode("Ri48eCx5PiA9IEZyZWVHcm91cCgpCnIgPSB4XjIqeV4tMwpIID0gRi5xdW90aWVudChbcl0pCnRpbWVpdCgiSChyKSA9PSBILm9uZV9lbGVtZW50KCkiKQ=="),globals())+"\\n");
execfile(os.path.abspath("___code___.py"))
File "", line 1, in <module>
File "/tmp/tmpjvXomU/___code___.py", line 6, in <module>
exec compile(u'timeit("H(r) == H.one_element()")
File "", line 1, in <module>
File "sage_timeit_class.pyx", line 114, in
sage.misc.sage_timeit_class.SageTimeit.__call__
(sage/misc/sage_timeit_class.c:931)
File "sage_timeit_class.pyx", line 78, in
sage.misc.sage_timeit_class.SageTimeit.eval
(sage/misc/sage_timeit_class.c:731)
File
"/usr/local/src/sage/sage-5.6.rc1.server/local/lib/python2.7/site-
packages/sage/misc/sage_timeit.py",
line 236, in sage_timeit
if timer.timeit(number) >= 0.2:
File
"/usr/local/src/sage/sage-5.6.rc1.server/local/lib/python/timeit.py", line
195, in timeit
timing = self.inner(it, self.timer)
File "<magic-timeit>", line 6, in inner
File "libgap_wrapper.pyx", line 492, in
sage.groups.libgap_wrapper.ElementLibGAP.__richcmp__
(sage/groups/libgap_wrapper.c:4013)
File "element.pyx", line 876, in
sage.structure.element.Element._richcmp
(sage/structure/element.c:8426)
File "element.pyx", line 923, in
sage.structure.element.Element._richcmp_c_impl
(sage/structure/element.c:8727)
File "libgap_wrapper.pyx", line 483, in
sage.groups.libgap_wrapper.ElementLibGAP._cmp_c_impl
(sage/groups/libgap_wrapper.c:3957)
File "element.pyx", line 913, in sage.structure.element.Element.__cmp__
(sage/structure/element.c:8597)
File "element.pyx", line 826, in sage.structure.element.Element._cmp
(sage/structure/element.c:7601)
File "element.pyx", line 539, in
sage.libs.gap.element.GapElement._cmp_c_impl
(sage/libs/gap/element.c:4484)
ValueError: libGAP: cannot compare: Segmentation fault
}}}
--
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/14025#comment:1>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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