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Re: Combinatorica versus new graphs in V8

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• Subject: [mg132487] Re: Combinatorica versus new graphs in V8
• From: "E. Martin-Serrano" <eMartinSerrano at telefonica.net>
• Date: Fri, 28 Mar 2014 03:32:10 -0400 (EDT)
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Many thanks Murray,

It is a pity.

I think that WRI could (and should)  have adopted a different approach to
migrate Combinatorica to the kernel. I suppose that there are many user
applications which make intensive use of Combinatorica. That is, at least,
in my case. And now, what?

E. Martin-Serrano.

-----Mensaje original-----
De: Murray Eisenberg [mailto:murray at math.umass.edu] 
Enviado el: jueves, 27 de marzo de 2014 10:00
Para: mathgroup at smc.vnet.net
Asunto: Re: Combinatorica versus new graphs in V8

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

• 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>