#6491: [with spkg, needs review] Modular Cohomology Rings of Finite p-Groups
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Reporter: SimonKing | Owner: SimonKing
Type: enhancement | Status: assigned
Priority: major | Milestone: sage-4.1.1
Component: optional packages | Keywords: cohomology ring finite p-group
Reviewer: | Author: Simon King
Merged: |
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Comment(by wdj):
1. Thanks for fixing the installation docs and the detailed comparison.
That was very valuable for me anyway.
2. The comparision between crime and your package is a bit more
complicated that it first seems I think. For example, we have
{{{
sage: from pGroupCohomology import CohomologyRing
sage: H = CohomologyRing.user_db(8,3,websource=False)
sage: print H
Cohomology ring of Dihedral group of order 8 with coefficients in GF(2)
Computed up to degree 2
Minimal list of generators:
[c_2_2, a 2-Cochain in H^*(D8; GF(2)),
b_1_0, a 1-Cochain in H^*(D8; GF(2)),
b_1_1, a 1-Cochain in H^*(D8; GF(2))]
Minimal list of algebraic relations:
[b_1_0*b_1_1]
sage: gap('LoadPackage("crime")')
true
sage: gap.eval("C:=CohomologyObject(DihedralGroup(8))")
'<object>'
sage: gap.eval("CohomologyGenerators(C,2)")
'[ 1, 1, 2 ]'
sage: gap.eval("CohomologyRelators(C,2)")
'[ [ z, y, x ], [ z*y+y^2 ] ]'
}}}
These seem different but I am not an expert. Is this difference easy to
explain?
3. Regarding the PoincareSeries in HAP: I think Graham Ellis told me that
his PoincareSeries was likely to be true but not guaranteed. Is this
right? If so, how sure are you of yours? (I checked in an example that
they agree.)
4. Regarding the license:
(a) Can you ask any surviving Meataxe people if they might relicensing the
version you used under GPLv2+?
(b) Since David Green is a co-author - he can license the code as he
wants:-)
(c) Did you create the database "Data for the cohomology of all groups of
order 64" yourself? If not, in the US I think this is not an issue, but
overseas copyright laws for databases are more complicated. Do you know
the distribution license for it?
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/6491#comment:12>
Sage <http://sagemath.org/>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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