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src/sage/groups/perm_gps/permgroup.py: bullet-proof a test #40441
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There's a test in this file that finds a random subgroup of SymmetricGroup(6) with three generators, round-trips it through a finite presentation, and then checks the result for isomorphism with itself. If you are unlucky, however, GAP will get confused, and raise a GAPError during the round trip. This was originally reported in issue 32141, and a workaround was added at some point. The workaround is a bit ugly though, and it does not make a lot of sense to test something that in fact does not work. I have tried all 2024 of them, and the same problem does not arise with subgroups of SymmetricGroup(4), so this commit reverts the workaround and then changes the 6 to a 4. (Five has the same problem that six does.) Closes: sagemath#32141
The old test asserts that either This pull request doesn't fix the underlying issue (that Gap sometimes complains) either. |
What should I do instead? The check for GAP gets overwhelmed trying to convert the presentation back to a permutation group, but that's not actually a failure in the method we are testing ( |
On further investigation, this is actually reasonable. That said, the As can be seen from the error, this is not the case. I cannot reproduce the issue locally either. |
Here is a reproducer:
Though for the mysteriousest of reasons, running the same line again just works:
|
I'm still not sure why running the same command twice works only the second time, but it's probably related to
|
sagemathgh-40441: src/sage/groups/perm_gps/permgroup.py: bullet-proof a test There's a test in this file that finds a random subgroup of `SymmetricGroup(6)` with three generators, round-trips it through a finite presentation, and then checks the result for isomorphism with itself. If you are unlucky, however, GAP will get confused, and raise a `GAPError` during the round trip. This was originally reported in sagemath#32141, and a workaround was added at some point. The workaround is a bit ugly though, and it does not make a lot of sense to test something that in fact does not work. I have tried all 2024 of them, and the same problem does not arise with subgroups of `SymmetricGroup(4)`, so this commit reverts the workaround and then changes the 6 to a 4. (Five has the same problem that six does.) Closes: sagemath#32141 URL: sagemath#40441 Reported by: Michael Orlitzky Reviewer(s):
sagemathgh-40441: src/sage/groups/perm_gps/permgroup.py: bullet-proof a test There's a test in this file that finds a random subgroup of `SymmetricGroup(6)` with three generators, round-trips it through a finite presentation, and then checks the result for isomorphism with itself. If you are unlucky, however, GAP will get confused, and raise a `GAPError` during the round trip. This was originally reported in sagemath#32141, and a workaround was added at some point. The workaround is a bit ugly though, and it does not make a lot of sense to test something that in fact does not work. I have tried all 2024 of them, and the same problem does not arise with subgroups of `SymmetricGroup(4)`, so this commit reverts the workaround and then changes the 6 to a 4. (Five has the same problem that six does.) Closes: sagemath#32141 URL: sagemath#40441 Reported by: Michael Orlitzky Reviewer(s):
sagemathgh-40441: src/sage/groups/perm_gps/permgroup.py: bullet-proof a test There's a test in this file that finds a random subgroup of `SymmetricGroup(6)` with three generators, round-trips it through a finite presentation, and then checks the result for isomorphism with itself. If you are unlucky, however, GAP will get confused, and raise a `GAPError` during the round trip. This was originally reported in sagemath#32141, and a workaround was added at some point. The workaround is a bit ugly though, and it does not make a lot of sense to test something that in fact does not work. I have tried all 2024 of them, and the same problem does not arise with subgroups of `SymmetricGroup(4)`, so this commit reverts the workaround and then changes the 6 to a 4. (Five has the same problem that six does.) Closes: sagemath#32141 URL: sagemath#40441 Reported by: Michael Orlitzky Reviewer(s):
sagemathgh-40441: src/sage/groups/perm_gps/permgroup.py: bullet-proof a test There's a test in this file that finds a random subgroup of `SymmetricGroup(6)` with three generators, round-trips it through a finite presentation, and then checks the result for isomorphism with itself. If you are unlucky, however, GAP will get confused, and raise a `GAPError` during the round trip. This was originally reported in sagemath#32141, and a workaround was added at some point. The workaround is a bit ugly though, and it does not make a lot of sense to test something that in fact does not work. I have tried all 2024 of them, and the same problem does not arise with subgroups of `SymmetricGroup(4)`, so this commit reverts the workaround and then changes the 6 to a 4. (Five has the same problem that six does.) Closes: sagemath#32141 URL: sagemath#40441 Reported by: Michael Orlitzky Reviewer(s):
sagemathgh-40441: src/sage/groups/perm_gps/permgroup.py: bullet-proof a test There's a test in this file that finds a random subgroup of `SymmetricGroup(6)` with three generators, round-trips it through a finite presentation, and then checks the result for isomorphism with itself. If you are unlucky, however, GAP will get confused, and raise a `GAPError` during the round trip. This was originally reported in sagemath#32141, and a workaround was added at some point. The workaround is a bit ugly though, and it does not make a lot of sense to test something that in fact does not work. I have tried all 2024 of them, and the same problem does not arise with subgroups of `SymmetricGroup(4)`, so this commit reverts the workaround and then changes the 6 to a 4. (Five has the same problem that six does.) Closes: sagemath#32141 URL: sagemath#40441 Reported by: Michael Orlitzky Reviewer(s):
There's a test in this file that finds a random subgroup of
SymmetricGroup(6)
with three generators, round-trips it through a finite presentation, and then checks the result for isomorphism with itself. If you are unlucky, however, GAP will get confused, and raise aGAPError
during the round trip. This was originally reported in #32141, and a workaround was added at some point.The workaround is a bit ugly though, and it does not make a lot of sense to test something that in fact does not work. I have tried all 2024 of them, and the same problem does not arise with subgroups of
SymmetricGroup(4)
, so this commit reverts the workaround and then changes the 6 to a 4. (Five has the same problem that six does.)Closes: #32141