#8667: New version of modular group cohomology spkg
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Reporter: SimonKing | Owner: SimonKing
Type: enhancement | Status: new
Priority: major | Milestone: sage-4.4
Component: optional packages | Keywords: modular cohomology finite group
Author: Simon King | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
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Comment(by SimonKing):
I posted another update of the package.
I tried to make the package robust enough so that after interruption of
Singular all relevant data are reconstructed, so that the computation can
be resumed. The update concerns a case where this failed. Here is the
relevant example (which forms a new doc test), that (in the originally
posted package) used to result in an error:
{{{
sage: from pGroupCohomology import CohomologyRing
sage: tmp = tmp_filename()
sage: CohomologyRing.set_user_db(tmp)
sage: H = CohomologyRing(48,50, prime=2)
sage: H.make()
sage: c =
H.subgroup_cohomology()('c_1_1*c_1_2^2*c_1_3^3+c_1_1*c_1_2^4*c_1_3+c_1_1*c_1_2^5+c_1_1^2*c_1_3^4+c_1_1^2*c_1_2*c_1_3^3+c_1_1^2*c_1_2^3*c_1_3+c_1_1^3*c_1_2^2*c_1_3+c_1_1^3*c_1_2^3+c_1_1^4*c_1_3^2+c_1_1^4*c_1_2*c_1_3+c_1_1^4*c_1_2^2+c_1_1^5*c_1_2+c_1_0*c_1_3^5+c_1_0*c_1_2^2*c_1_3^3+c_1_0*c_1_2^3*c_1_3^2+c_1_0*c_1_1^2*c_1_2*c_1_3^2+c_1_0*c_1_1^2*c_1_2^2*c_1_3+c_1_0*c_1_1^2*c_1_2^3+c_1_0*c_1_1^3*c_1_3^2+c_1_0*c_1_1^3*c_1_2^2+c_1_0*c_1_1^4*c_1_3+c_1_0*c_1_1^5+c_1_0^2*c_1_3^4+c_1_0^2*c_1_2^2*c_1_3^2+c_1_0^2*c_1_2^3*c_1_3+c_1_0^2*c_1_2^4+c_1_0^2*c_1_1*c_1_3^3+c_1_0^2*c_1_1*c_1_2^2*c_1_3+c_1_0^2*c_1_1^2*c_1_2*c_1_3+c_1_0^2*c_1_1^2*c_1_2^2+c_1_0^2*c_1_1^3*c_1_2+c_1_0^3*c_1_2*c_1_3^2+c_1_0^3*c_1_1*c_1_2^2+c_1_0^3*c_1_1^2*c_1_3+c_1_0^3*c_1_1^3+c_1_0^4*c_1_3^2+c_1_0^4*c_1_2*c_1_3+c_1_0^4*c_1_2^2+c_1_0^4*c_1_1*c_1_2+c_1_0^4*c_1_1^2+c_1_0^5*c_1_3+c_1_0^5*c_1_1')
sage: d = H.stable_to_polynomial(c); d
c_3_6^2+c_3_2*c_3_7+c_3_2*c_3_6+c_3_0*c_3_7+c_3_0*c_3_6+c_3_0*c_3_5+c_3_0*c_3_4+c_3_0*c_3_3+c_2_3^3+c_2_2*c_2_3^2+c_2_1^2*c_2_3+c_2_1^3+c_2_0*c_2_3^2+c_2_0*c_2_1*c_2_2+c_2_0*c_2_1^2+c_2_0^2*c_2_3:
6-Cocycle in H^*(SmallGroup(48,50); GF(2))
sage: singular.quit()
sage: d == H.stable_to_polynomial(c)
True
}}}
Explanation: In the last line (i.e., after quitting Singular), the data of
`c`, the data of `d` and the underlying data used in
`stable_to_polynomial` are automatically reconstructed, so that the
computation can be repeated, yielding the same result.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/8667#comment:4>
Sage <http://www.sagemath.org>
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