Tommy Hofmann

Names for group types

3

I am writing down new names for the types related to groups: https://hackmd.io/ONVPdlfARgWzkfkNkcJkgA?both#Something-with-groups I would appreciate some help with it @ThomasBreuer @fingolfin @fieker. I guess we can live with `FinGenGrpAb`?...

``` julia> basis_matrix(0 * maximal_order(quadratic_field(-1)[1])) [0 0] [0 0] julia> basis(0 * maximal_order(quadratic_field(-1)[1])) 2-element Vector{NfOrdElem}: 0 0 ``` This does not make much sense. P.S.: Magma does the "right" thing.

Ray class group map could be a bit more intelligent

2

We can map factored ideals to ray class groups, but the individual factors need to be coprime to the modulus: https://github.com/thofma/Hecke.jl/blob/60a055cf6d9a54784a3dca18e56c090b20282e50/src/NumFieldOrd/NfOrd/RayClassGrp.jl#L785-L792 I think we can do better. Here is a...

_Originally posted by @fingolfin in https://github.com/oscar-system/Oscar.jl/pull/2925#discussion_r1372101285_

Rainy day todo list for algebras: - [ ] Add `hom(A, B, ::Vector)` constructor. - [ ] Morphisms defined by `hom(A, B, data)` do not check whether they are morphisms....

As discussed with @ThomasBreuer, I open this issue so that we don't lose track: ``` julia> natural_character(symplectic_group(4, 2)) ERROR: MethodError: no method matching conjugacy_classes(::Nothing) [...] Stacktrace: [1] natural_character(G::MatrixGroup{FqFieldElem, FqMatrix}) @...

Irreducible modules gives wrong results

7

Reported by Tobias Metzlaff on slack: ```julia julia> W=symmetric_group(3) Sym( [ 1 .. 3 ] ) julia> X=character_table(W) Sym( [ 1 .. 3 ] ) 2 1 1 . 3...