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Re: Combinatorica versus new graphs in V8

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• Subject: [mg132482] Re: Combinatorica versus new graphs in V8
• From: Itai Seggev <itais at wolfram.com>
• Date: Fri, 28 Mar 2014 03:30:30 -0400 (EDT)
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Both mixed graphs and multigraphs are planned for version 10.

>  27 2014 03:59:34 Murray Eisenberg 

> I believe there's NO way to implement multiple edges in a
> System`Graph object. In fact, you undoubtedly saw, when you tried, the
> error message:
>
>   Graph::supp: Mixed graphs and multigraphs are not supported.
>
> Moving the functionality of the graph-theoretic functions from the
> Combinatorica add-on to the kernel has been a slow process over several
> versions of Mathematica and evidently is not yet complete.
>
> We can only hope that the next version of Mathematica, already documented
> in preliminary form at
>
>   http://reference.wolfram.com/language/
>
> will allow multiple edges at long last.
>
> On Mar 26, 2014, at 3:23 AM, E. Martin-Serrano
<eMartinSerrano at telefonica.net> wrote:
> > Hi,
> >
> > I am unable to see how to  implement multi edge graphs for pairs of
> > vertices in V8.
> >
> > With the =91Combinatorica=92 package this was easy to do as in
> >
> > << Combinatorica`
> >
> > g = Combinatorica`Graph[{{{1, 2}}, {{2, 3}}, {{2, 3}}, {{2, 3}} , {{2,
> > 3}}}, {{{0, 0}}, {{1, 1}}, {{2, 0}}}]
> >
> > ShowGraph[g]
> >
> > Here I have three =91{2,3}=92 concurrent edges for the  vertices pair
> > {2,3}
> >
> > The following should be equivalent for the V8  kernel implementation of
> > graphs
> >
> > System`Graph[{UndirectedEdge[1,2], UndirectedEdge[2,3],
> > UndirectedEdge[2,3], UndirectedEdge[2,3], UndirectedEdge[2,3]},
> >
> > VertexCoordinates -> {{0, 0}, {1, 1}, {2, 0}}]
> >
> > But the multiple edges feature does not work in the way it did in
> > =91Combinatorica=92 (It does not work in any way).
> >
> > Please, could anyone say what I am missing here?
> >
> >
> > E. Martin
> >
> >
> >
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> Murray Eisenberg                                murray at math.umass.edu
> Mathematics & Statistics Dept.
> Lederle Graduate Research Tower      phone 240 246-7240 (H)
> University of Massachusetts
> 710 North Pleasant Street
> Amherst, MA 01003-9305

--
Itai Seggev                              
Mathematica Alogirthms R&D     
Wolfram Research, Inc.       

• References:
  • Combinatorica versus new graphs in V8
    • From: "E. Martin-Serrano" <eMartinSerrano@telefonica.net>
  • Re: Combinatorica versus new graphs in V8
    • From: Murray Eisenberg <murray@math.umass.edu>