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Re: Graphtheory package questions

  • To: mathgroup at smc.vnet.net
  • Subject: [mg35955] Re: [mg35918] Graphtheory package questions
  • From: Rob Pratt <rpratt at email.unc.edu>
  • Date: Fri, 9 Aug 2002 05:18:03 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

On Thu, 8 Aug 2002, Oliver Friedrich wrote:

> Hallo,
> 
> I'm running 3.0.
> 
> I want to do a document about network analysis of electrical networks by
> means of that things like method of node potentials and method of mesh
> currents, OK?
> Now I think that the DiscreteMath'Combinatorica package provides some nice
> features to generate, show and operate with graphs.
> 
> I want to generate a graph out of a given netlist (almost SPICE format) and
> display that graph. The vertices would be the nodes of the circuit, the
> edges would be the components of the circuit.
> 
> 1. I didn't find a suitable embedding of a circuit graph. It would be nice
> to generate an embedding which would avoid any intersections of edges if
> possible. In my case it is possible, because my circuit diagram doesn't have
> any crossings of lines. Is there an automatic embedding doing that or do I
> have to generate my vertices list by hand?
> 
> 2. All the graphs shown in the package help don't have any vertices or edges
> named with a reference. You can imagine, it's not useful to show a graph of
> a circuit, where neither the components references nor the node references
> are shown. Is there way to give the vertices a name and display that name in
> the graph? The same for the edges.
> 
> 3. I couldn' find that book of Steven Skiena anymore. Is there any
> documentation on that package beside the Online help and that book?
> 
> Thanks for your help and especially greetings to David Park, my inquiry
> sounds like it has to do with your drawing package ;-)
> 
> Oliver Friedrich

There is an updated version of Combinatorica available at
www.combinatorica.com.  Some of the commands require Mathematica 4.0,
though.

1. There is no command to automatically generate a plane embedding of a
planar graph, although a result of Wagner (1936) and Fary (1948) states
that every planar graph has a straight-line embedding.  However, there is
a command, PlanarQ, that determines whether a graph is planar or not.

2. The new Combinatorica includes numerous labeling options.

3. Skiena's book is out of print, but Cambridge University Press is
publishing a new version.

Rob Pratt
Department of Operations Research
The University of North Carolina at Chapel Hill

rpratt at email.unc.edu

http://www.unc.edu/~rpratt/



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