#4115: [with patch, needs review] Double coset problems
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Reporter: rlm | Owner: rlm
Type: defect | Status: new
Priority: major | Milestone: sage-3.1.3
Component: group_theory | Resolution:
Keywords: |
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Comment (by wdj):
I'm confused by this output:
Put
{{{
def test():
G = SymmetricGroup(20)
g = G("(11,12,13,14,15,16,17)")
for i in range(10):
C1 = RandomLinearCode(20,10,GF(2))
C2 = C1.permuted_code(g)
CW1 = matrix(GF(2),C1.list())
CW2 = matrix(GF(2),C2.list())
B = NonlinearBinaryCodeStruct(CW1)
C = NonlinearBinaryCodeStruct(CW2)
ans = B.is_isomorphic(C)
L = [j+1 for j in ans]
h = G(L)
G1 = C1.automorphism_group_binary_code()
print i, g, h, h*g^(-1) in G1
}}}
called test.sage or something and attach it.
It seems to me it should always return True.
{{{
sage: time test()
0 (11,12,13,14,15,16,17) (11,12,13,14,15,16,17) True
1 (11,12,13,14,15,16,17) (11,12,13,14,15,16,17) True
2 (11,12,13,14,15,16,17) (11,12,13,14,15,16,17) True
3 (11,12,13,14,15,16,17) (11,12,13,14,15,16) True
4 (11,12,13,14,15,16,17) (9,12,13,14,15,16,17) False
5 (11,12,13,14,15,16,17) (11,12,13,14,15,16,17) True
6 (11,12,13,14,15,16,17) (11,12,13,14,15,16,17) True
7 (11,12,13,14,15,16,17) (11,12,13,14,15,16,17) True
8 (11,12,13,14,15,16,17) (11,12,13,14,15,16,17) True
9 (11,12,13,14,15,16,17) (11,12,13,14,15,16,17) True
CPU times: user 88.99 s, sys: 0.10 s, total: 89.09 s
Wall time: 90.93 s
}}}
If you change the script to
{{{
def test():
G = SymmetricGroup(20)
g = G("(11,12,13,14,15,16,17)")
for i in range(10):
C1 = RandomLinearCode(20,10,GF(2))
C2 = C1.permuted_code(g)
CW1 = matrix(GF(2),C1.list())
CW2 = matrix(GF(2),C2.list())
B = NonlinearBinaryCodeStruct(CW1)
C = NonlinearBinaryCodeStruct(CW2)
ans = B.is_isomorphic(C)
L = [j+1 for j in ans]
h = G(L)
G1 = C1.automorphism_group_binary_code()
print i, g, h, h^(-1)*g in G1
}}}
you get
{{{
sage: time test()
0 (11,12,13,14,15,16,17) (11,12,13,14,15,16,17) True
1 (11,12,13,14,15,16,17) (11,12,13,14,15,16,17) True
2 (11,12,13,14,15,16,17) (11,12,13,14,15,16,17) True
3 (11,12,13,14,15,16,17) (11,12,13,14,15,16,17) True
4 (11,12,13,14,15,16,17) (11,12,13,14,15,16,17) True
5 (11,12,13,14,15,16,17) (8,15,16,17,11)(12,13,14) False
6 (11,12,13,14,15,16,17) (10,12,13,14,15,16,17) False
7 (11,12,13,14,15,16,17) (11,12,13,14,15,16,17) True
8 (11,12,13,14,15,16,17) (9,12,13,14,15,16,17) False
9 (11,12,13,14,15,16,17) (11,12,13,14,15,16,17) True
CPU times: user 92.33 s, sys: 0.11 s, total: 92.45 s
Wall time: 92.92 s
}}}
Again funny.
It should be g,h:C1->C2, so h^(-1)*g in G1 should be true
and h*g^(-1) in G1 should be false.
I'm probably misinterpreting something in the docstrings
(and probably and still too sleepy to think straight:-)
but something seems confusing to me here.
Can someone see the error here?
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/4115#comment:12>
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