#14291: Orbits of tuples and sets
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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:
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Comment (by dimpase):
Replying to [comment:21 ncohen]:
> Yoooooooooooo !
>
> > this is too ugly, uglier than using a class, or whatever. Actually, I
think it is simply wrong to let groups act on some totally unstructured
arbitrary sh*t, and this is exactly what happens right now with allowing
arbitrary domain elements, for which any relation to the original domain
is lost.
>
> Ahahaha. Deal. Do I remove all support for labels on edges and vertices
from graphs ? I am sooooooooooo eager to `:-P`
I don't think this is relevant. Here we have an example of a group acting
on triples, and this is a kind of "primitive" action, all the other
actions originate from it.
Anyhow, there is a hack which might fix all our sorrows: namely, add an
extra level of () to the "most primitive" elements of the
domain. I.e. if instead of {1,2,3,4,{1,2},{2,3}} there was a domain
`{{1},{2},{3},{4},{1,2},{2,3}}` then the ambiguity does not arise, for
{1,2} and `{{1},{2}}` are different things now.
Dima
>
> > Say, if the domain of a group is {1,2,3,4,{1,2},{2,3}}, the very
notion of the orbit of {1,2} is becoming ambiguous, as in a sane world
{1,2} is a subset of {1,2,3,4}, and not a random label.
>
> Well, in Sage however it is not ambiguous :
> {{{
> g.orbit(Set([1,2]),action="OnPoints")
> g.orbit(Set([1,2]),action="OnSets")
> }}}
>
> Nathann
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/14291#comment:22>
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