Perhaps the correct thing to do is have BipartiteGraph wrap a Graph
rather than descend from it. This way at least one wouldn't ever
accidently get incorrect answers when calling graph methods that have
different definitions in the bipartite case (including methods that
may in the future get added to Graph).
- Robert
On Feb 27, 2010, at 6:37 AM, David Joyner wrote:
First, you should pay more attention to what
Robert Miller says instead of me, since he
knows the code much much better. I'm cc'ing this
back to sage-devel; hope you don't mind.
There are several places where bipartite graphs
differ (at least in the literature) from regular graphs.
For example, usually the bipartite graph's adjacency matrix
is not square. Also, the vertices are usually drawn
using 2 colors, so the plot methods might be
different. Neither of these seem to be implemented
in Sage. (Also, the docstring has my favorite
self-reference:
sage: BipartiteGraph?
yields:
...
Docstring:
Create a bipartite graph. See documentation: BipartiteGraph?
...
Also, the EXAMPLE is not formatted correctly.)
As for usage, the Tanner graph of a binary code is
the bipartite graph whose adjacency matrix is the
check matrix of the code. I'm sure there are many other
applications but that is the one that first springs to mind.
On Sat, Feb 27, 2010 at 8:49 AM, Nathann Cohen <nathann.co...@gmail.com
> wrote:
Hello everybody !!!
I followed your conversation on Sage-devel (http://bit.ly/bHTOHm),
and
I felt a bit as an outsider as I never used this class.. Could you
tell me what you expect from it, or what you use it for ? I can not
dream of a situation in which I would prefer it to the usual Graph
class.....
Thank you :-)
Nathann
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