Opened 17 months ago

Last modified 5 weeks ago

#28150 new defect

Bugs in subgroups of a subgroup of an abelian group

Reported by: mathzeta2 Owned by:
Priority: major Milestone: sage-9.3
Component: group theory Keywords: abelian group fpsac2019
Cc: Merged in:
Authors: Reviewers:
Report Upstream: N/A Work issues:
Branch: Commit:
Dependencies: Stopgaps:


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

G = AbelianGroup([3, 3])
H = G.subgroup([G.gen()])
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/ 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])

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 (4)

comment:1 Changed 17 months ago by mathzeta2

  • Keywords fpsac2019 added; fpsac removed

comment:2 Changed 11 months ago by embray

  • Milestone changed from sage-8.9 to sage-9.1

Ticket retargeted after milestone closed

comment:3 Changed 7 months ago by mkoeppe

  • Milestone changed from sage-9.1 to sage-9.2

Moving tickets to milestone sage-9.2 based on a review of last modification date, branch status, and severity.

comment:4 Changed 5 weeks ago by mkoeppe

  • Milestone changed from sage-9.2 to sage-9.3
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