Add functions to get more series of subgroups (#2728)

Also add many more examples to existing docstrings.
oscar-system · Oct 16, 2023 · de48051 · de48051
1 parent 49a1acf
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diff --git a/docs/src/Groups/basics.md b/docs/src/Groups/basics.md
@@ -94,4 +94,5 @@ exponent(G::GAPGroup)
 describe(G::GAPGroup)
 nilpotency_class(G::GAPGroup)
 prime_of_pgroup
+derived_length
 ```
diff --git a/docs/src/Groups/subgroups.md b/docs/src/Groups/subgroups.md
@@ -55,6 +55,12 @@ hall_subgroup_reps
 hall_system
 complement_class_reps
 complement_system
+chief_series
+composition_series
+jennings_series
+p_central_series
+lower_central_series
+upper_central_series
 ```
 
 !!! note

diff --git a/experimental/LieAlgebras/src/LieAlgebras.jl b/experimental/LieAlgebras/src/LieAlgebras.jl
@@ -48,6 +48,7 @@ import ..Oscar:
   is_solvable,
   is_welldefined,
   kernel,
+  lower_central_series,
   matrix,
   ngens,
   normalizer,
@@ -95,7 +96,6 @@ export is_symmetric_power
 export is_tensor_power
 export is_tensor_product
 export lie_algebra
-export lower_central_series
 export matrix_repr_basis
 export multicombinations
 export permutations
@@ -157,7 +157,6 @@ export is_symmetric_power
 export is_tensor_power
 export is_tensor_product
 export lie_algebra
-export lower_central_series
 export matrix_repr_basis
 export special_linear_lie_algebra
 export special_orthogonal_lie_algebra

diff --git a/src/Groups/GAPGroups.jl b/src/Groups/GAPGroups.jl
@@ -312,6 +312,11 @@ function Base.show(io::IO, G::PermGroup)
       else
         print(io, " and infinite order")
       end
+    elseif GAP.Globals.HasStabChainMutable(G.X)
+      # HACK: to show order in a few more cases where it is trivial to get
+      # but really, GAP should be using this anyway?
+      s = GAP.Globals.SizeStabChain( GAP.Globals.StabChainMutable( G.X ) )
+      print(io, " and order ", ZZRingElem(s))
     end
   end
 end
@@ -1923,19 +1928,6 @@ function (G::FPGroup)(pairs::AbstractVector{Pair{T, S}}) where {T <: IntegerUnio
    return FPGroupElem(G, w)
 end
 
-@doc raw"""
-    nilpotency_class(G::GAPGroup) -> Int
-
-Return the nilpotency class of `G`, i.e.,
-the smallest integer $n$ such that `G` has a central series of length $n$.
-
-An exception is thrown if `G` is not nilpotent.
-"""
-@gapattribute function nilpotency_class(G::GAPGroup)
-   @assert is_nilpotent(G) "The group is not nilpotent."
-   return GAP.Globals.NilpotencyClassOfGroup(G.X)::Int
-end
-
 
 function describe(G::GrpAbFinGen)
    l = elementary_divisors(G)