#14291: Orbits of tuples and sets
---------------------------------+------------------------------------------
Reporter: ncohen | Owner: joyner
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-5.9
Component: group theory | Resolution:
Keywords: | Work issues:
Report Upstream: N/A | Reviewers:
Authors: Nathann Cohen | Merged in:
Dependencies: | Stopgaps:
---------------------------------+------------------------------------------
Comment (by dimpase):
Replying to [comment:30 ncohen]:
> > 2. We convince the other author that I am right, and drop the
workaround.
>
> Come on Dima, you do understand that on some instances your patch could
return bad answers, do you ?
On wrong instances, yes. On instances like (1,2,{1,2},...), which make no
sense, because they lead to horrible bugs. Here is how.
Take, say, directed 3-cycle, and label its vertices, in the cyclic order,
1, 2, (1,2). So you get G=Z_3, the automorphism group of this digraph,
acting on the domain V=(1,2,(1,2)). Next, ask for the orbit of the
**arc** (1,2) of the digraph under G. OK, fine, it is
A=((1,2),(2,(1,2)),((1,2),1). Now, note that the intersection of V and A
equals {(1,2)}. The intersection of two distinct orbits of a group is not
empty...
Would Évariste Galois raise from his grave and chase the designer of this?
:–)
>
> What's the problem with gessing the "depth" of input/output according to
the value of `action` ?
this won't fix the bug above.
Dima
>
> Nathann
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/14291#comment:31>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
--
You received this message because you are subscribed to the Google Groups
"sage-trac" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
Visit this group at http://groups.google.com/group/sage-trac?hl=en.
For more options, visit https://groups.google.com/groups/opt_out.
