#6750: [with spkg, needs review] New version of optional Group Cohomology spkg
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Reporter: SimonKing | Owner: SimonKing
Type: enhancement | Status: assigned
Priority: major | Milestone:
Component: optional packages | Keywords: cohomology ring p-group
Reviewer: | Author: Simon King
Merged: |
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Comment(by SimonKing):
Replying to [comment:38 SimonKing]:
> Thanks to Mikael Vejdemo Johansson, I detected another bug in the
computation of restricted Massey powers. In this example (cohomology of
C_4 times C_4), the answers of COHO.massey_products() and of
COCH.massey_power() were inconsistent.
>
> It is fixed, ...
... and the technical problem was as follows: In COCH.massey_power() was a
loop starting at 0, but it should have started at 1. By consequence, a
cocycle (which in general would be non-zero) was added to itself,
resulting in zero (in characteristic two).
The only change in the code is to let this loop start at 1, and then of
course there are new doc tests.
Just for the record...
Cheers,
Simon
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/6750#comment:39>
Sage <http://sagemath.org/>
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