- To: mathgroup at smc.vnet.net
- Subject: [mg60946] graphs
- From: leigh pascoe <leigh at cephb.fr>
- Date: Wed, 5 Oct 2005 02:27:47 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
I am using Combinatorica to study a board game represented by a graph.
The nxn graph can be created using
The vertices of the graph are numbered from the bottom left in rows,
hence to refer to the matrix (row,column) location of a vertex we define
a linking function.
Now to complete the graph we draw edges from cell(i,j) to cell(i-1,j+1),
where these vertices exist. Here is an example for the 4x4 case
This works ok, but I now have several problems: I would like to write
the above statement as an implied loop for a general nxn gridgraph. I
can't seem to get the correct syntax for this. Can anyone help me?
Then I would like to define some functions on the graph, referring to
the vertices by there grid position. However when I add or delete a
vertex, the numbering on the graph changes. I would like to be able
mutate the graph, but still be able to address vertices by the original
labels, as defined by the cellindex[i,j] function (or any other for that
matter. Any suggestions?
A third problem (bug?) is that in the ShowGraph command the vertex label
on the left loses the left most digit(s) when displayed, as shown above.
I just note that here in case someone at Wolfram wants to fix it.
The documentation for this package is also rather (very) limited. I
bought the book on the package, which gives some more details, but many
functions still remain undocumented. Does anyone know a better source?
Thanks for your replies.
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