#4105: multiplication of permutations in distinct subgroups sometimes doesn't
work
--------------------------+-------------------------------------------------
Reporter: was | Owner: joyner
Type: defect | Status: new
Priority: minor | Milestone: sage-3.1.3
Component: group_theory | Keywords:
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I think the following session (reported by Beezer) says it all:
{{{
tetra=AlternatingGroup(4)
stab1=PermutationGroup_subgroup(tetra, ["(1,2,3)"])
stab4=PermutationGroup_subgroup(tetra, ["(2,3,4)"])
for g in stab1:
for h in stab4:
print g*h
///
Traceback (most recent call last): print g*h
File "/home/wstein/sage/local/lib/python2.5/site-
packages/SQLAlchemy-0.4.6-py2.5.egg/", line 3, in <module>
File "element.pyx", line 1090, in
sage.structure.element.MonoidElement.__mul__
(sage/structure/element.c:7938)
File "coerce.pyx", line 651, in
sage.structure.coerce.CoercionModel_cache_maps.bin_op
(sage/structure/coerce.c:6154)
File "permgroup_element.pyx", line 463, in
sage.groups.perm_gps.permgroup_element.PermutationGroupElement._r_action
(sage/groups/perm_gps/permgroup_element.c:3598)
File "permgroup_element.pyx", line 254, in
sage.groups.perm_gps.permgroup_element.PermutationGroupElement.__init__
(sage/groups/perm_gps/permgroup_element.c:2097)
File "/home/wstein/sage/local/lib/python2.5/site-
packages/sage/groups/perm_gps/permgroup_named.py", line 134, in __init__
raise ValueError, "n (=%s) must be >= 1"%n
ValueError: n (=0) must be >= 1
}}}
{{{
tetra=AlternatingGroup(4)
stab1=PermutationGroup_subgroup(tetra, ["(1,2,3)"])
stab4=PermutationGroup_subgroup(tetra, ["(2,3,4)"])
for g in stab1:
for h in stab4:
print tetra(g)*tetra(h)
///
()
(2,3,4)
(2,4,3)
(1,2,3)
(1,3)(2,4)
(1,4,3)
(1,3,2)
(1,4,2)
(1,2)(3,4)
}}}
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/4105>
SAGE <http://sagemath.org/>
Sage - Open Source Mathematical Software: Building the Car Instead of
Reinventing the Wheel
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