add support for Brueckner... #985
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fingolfin
reviewed
Jan 17, 2022
fingolfin
reviewed
Jan 17, 2022
| """ | ||
| function extension(c::CoChain{2,PermGroupElem}) | ||
| function extension(c::CoChain{2,<:Oscar.GAPGroupElem}) |
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TODO: we need a version for this that takes PcGroups and produces PcGroups
fingolfin
reviewed
Jan 17, 2022
experimental/GModule/GModule.jl
Outdated
| @@ -536,7 +541,7 @@ end | |||
| if isdefined(Hecke, :stub_composition_factors) | |||
| function Hecke.stub_composition_factors(x::Vector{T}) where {T} | |||
| F = base_ring(x[1]) | |||
| h = Oscar.iso_oscar_gap(F) | |||
| h = Oscar.ring_iso_oscar_gap(F) | |||
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We renamed Oscar.ring_iso_oscar_gap to Oscar.iso_oscar_gap ...
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just done, but still:
julia> Oscar.RepPc.reps(abelian_closure(QQ)[1], G)
ERROR: failed to convert GAP.GapObj to any known type:
GAP: !Z(137)^0
Stacktrace:
[1] gap_to_julia(x::GAP.GapObj; recursive::Bool)
@ GAP ~/.julia/dev/GAP/src/gap_to_julia.jl:321
[2] #gap_to_julia#29
@ ~/.julia/dev/GAP/src/gap_to_julia.jl:94 [inlined]
[3] #gap_to_julia#27
@ ~/.julia/dev/GAP/src/gap_to_julia.jl:89 [inlined]
[4] #36
@ ~/.julia/dev/GAP/src/gap_to_julia.jl:204 [inlined]
I thought this was solved?
fingolfin
requested changes
Jan 19, 2022
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ring_iso_oscar_gapmust be changed toiso_oscar_gap- many lines are not covered by tests, hence the above issue is not detect by the tests. I don't want to block the PR over this, but I think it'd be good to have a few (even trivial!) tests otherwise we'll just break this code constantly
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On Wed, Jan 19, 2022 at 09:30:59AM -0800, Max Horn wrote:
@fingolfin requested changes on this pull request.
- `ring_iso_oscar_gap` must be changed to `iso_oscar_gap`
- many lines are not covered by tests, hence the above issue is not detect by the tests. I don't want to block the PR over this, but I think it'd be good to have a few (even trivial!) tests otherwise we'll just break this code constantly
in PR 970 are some tests
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#985 (review)
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pc_group(GrpAb)
pc_group(Module{FinFieldElem}
needs, unfortunately, fixes in AA:
hash(ModuleElem)
quo for indirect submodules
G = small_group(24, 12) G = isomorphic_fp_group(G)[1] z = maximal_abelian_quotient(G) sub(z[1], map(x->PcGroupElem(z[1], x), GAP.Globals.Pcgs(z[1].X))) zz = z[2]*inv(ans[2]) a = Oscar.RepPc.brueckner(zz); b = [Oscar.RepPc.brueckner(x) for x = a]; runs - but crashes...
at least as far as it is implemented. ``` G = small_group(24, 12) G = isomorphic_fp_group(G)[1] z = maximal_abelian_quotient(G) sub(z[1], map(x->PcGroupElem(z[1], x), GAP.Globals.Pcgs(z[1].X))) zz = z[2]*inv(ans[2]) a = Oscar.RepPc.brueckner(zz); b = [Oscar.RepPc.brueckner(x) for x = a]; ``` finds a lot of pc-presentations of G, well too many of them. There is a part of the Thesis that is not yet implented...
Still problems: ``` F = free_group(2) a, b = gens(F) l = [a^2*b*a^−1*b*a^−1*b^−1*a*b^−2,a^2*b^−1*a*b^−1*a*b*a^−1*b^2]; G = quo(F, l)[1] q, mq = maximal_abelian_quotient(G) a = Oscar.RepPc.brueckner(mq); b = Oscar.RepPc.brueckner(a[3]); c = Oscar.RepPc.brueckner(b[3]); ``` (Brueckner's group G_1)
- Thm 15 (b) and (c) - Lemma 16 - replace some(?) hnf by rref/GF(p) - see if one can use F_p-modules? - make Tommy happy: do minimal_field for number fields
hopefully: ``` G = transitive_group(8, 5) irreducible_modules(AnticNumberField, G) C = ans[end] k = base_ring(C) K = cyclotomic_field(8)[1] issubfield(k, K) _, em = ans; F = free_module(K, 2) CC = gmodule(group(C), [hom(F, F, map_entries(em, mat(x))) for x= C.ac]) t = matrix(K, 2, 2, [rand(K, -5:5) for i=1:4]) CCC = gmodule(G, [hom(F, F, inv(t)*mat(x)*t) for x = CC.ac]) Oscar.GModuleFromGap.gmodule_over(em, CCC) z = ans; map(mat, z.ac) gmodule(QQ, z) simplify(ans) map(mat, ans.ac) ```
fingolfin
approved these changes
Feb 9, 2022
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