Re: Kernel crash?
- To: mathgroup at smc.vnet.net
- Subject: [mg47644] Re: [mg47632] Kernel crash?
- From: "J. McKenzie Alexander" <jalex at lse.ac.uk>
- Date: Tue, 20 Apr 2004 03:18:48 -0400 (EDT)
- References: <NDBBJGNHKLMPLILOIPPOMEGDEAAA.firstname.lastname@example.org>
- Sender: owner-wri-mathgroup at wolfram.com
> But why are you using All? Aren't the edge options principally for
> specifying the plot rendering?
Principally, but not always. Edge options can also include EdgeWeight
and EdgeDirection, both of which typically have meaning beyond plot
> Are you actually going to plot a graph with 39,600 edges?
Not if I can help it! But I'm using the Combinatorica graph creation
functions as part of a Mathematica package for local interaction models
of evolutionary games. The graphs specifying the local interaction
structure are first created in Combinatorica, then shovelled into a
Java object via JLink to "wire up" the local interaction structure.
When edges contain information like a weight or a direction, that has a
intended interpretation which needs to be handled correctly. I was
originally relying on Combinatorica calls like Edges[g, All] and
MakeDirected[g, All] to make sure I got all necessary information.
More importantly, though, there's no reason why MakeDirected[g,All]
should fail with a GridGraph[100,100]. The directed graph structure -
if you produce it "by hand" - only takes up around 3110000 bytes of
> I'm guessing that when you specify edge or vertex options,
> Combinatorica goes to much less efficient internal storage.
But the odd thing is that the final *output* for the the call which
crashes the kernel doesn't take any more storage than the output
returned by the call which doesn't. I.e.,
And the reason for this is that there *are no* edge or vertex options
originally specified for a grid graph.
So the reason for the kernel crash must solely depend on differences in
how MakeDirected[_] and MakeDirected[_,All] are implemented. A query
to ?MakeDirected states that "Calling the function with the tag All, as
MakeDirected[g, All], ensures that local options associated with each
edge are inherited by both
corresponding directed edges." Given this spec, the following is
functionally equivalent to MakeDirected[g,All]:
More importantly, it works:
â??Graph:< 19800, 10000, Undirected>â??
â??Graph:<39600, 10000, Undirected>â??
So there is a bug somewhere, but where?
Dr J. McKenzie Alexander
Department of Philosophy, Logic and Scientific Method
London School of Economics and Political Science
Houghton Street, London WC2A 2AE
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