Opened 5 months ago

Last modified 5 months ago

#28150 new defect

Bugs in subgroups of a subgroup of an abelian group

Reported by: mathzeta2 Owned by:
Priority: major Milestone: sage-8.9
Component: group theory Keywords: abelian group fpsac2019
Cc: Merged in:
Authors: Reviewers:
Report Upstream: N/A Work issues:
Branch: Commit:
Dependencies: Stopgaps:

Description

The following raises an exception at least on versions 8.7 and 8.9.beta1:

G = AbelianGroup([3, 3])
H = G.subgroup([G.gen()])
H.subgroups()
[snip]
RuntimeError: Gap produced error output
Error, families of <gens> and <M> are different

   executing H:=Subgroup(G,gensH);

From a brief overview of src/sage/groups/abelian_gps/abelian_group.py the docs for AbelianGroup_class.subgroup() mentions "The 'big' group must be defined using 'named' generators". But trying

G.<a, b> = AbelianGroup([3, 3])
H = G.subgroup([a])
H.subgroups()

gives the same error. Also AbelianGroup_subgroup.gen() does not have a default argument for the first generator, like AbelianGroup_class.gen() and many of the gen() methods in Sage.

Change History (1)

comment:1 Changed 5 months ago by mathzeta2

  • Keywords fpsac2019 added; fpsac removed
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