Hello,

Well, this looks like a very interesting thing to add to sage. I am sure 
that the graph-guys around here would be enthousiastic, were it not for the 
summer vacations..

Could you open a ticket on trac for that ? and prepare and upload a patch ? 
Do you need help to do that ?

http://trac.sagemath.org

Or maybe you can first work with the sage-combinat branch, if you prefer. 
That's a good way to prepare something for insertion into sage. 

http://wiki.sagemath.org/combinat

Cheers,

Frederic

Le jeudi 26 juillet 2012 02:14:41 UTC+2, Keeler Russell a écrit :
>
> Hello everyone,
>
> I've been working on a function to calculate the chromatic symmetric 
> function (a.k.a. CSF) of a graph as part of a related research project. You 
> can find the code here: https://github.com/keeler/csf (the files are 
> csf.py and csf.pyx, in particular). I wanted to know if this function would 
> be useful to anyone, and would greatly appreciate any tips regarding how to 
> improve its performance.
>
> Notes on the algorithm: I use Thm 2.5 from Stanley's "A Symmetric 
> Function Generalization of the Chromatic Polynomial of a Graph" to 
> calculate the CSF. This is pretty directly reflected in the code in csf.py. 
> However, csf.pyx uses a bit more machinery. First of all, it stores the 
> coefficients of the corresponding power-sum symmetric function terms in a 
> dictionary of speedy access. Second, I represent the elements in each edge 
> set with a bitset (1 for included, 0 for excluded). Third, I use Gray Codes 
> to either add or delete a single edge for each iteration.
>
> If you have any questions for me, or would like me to provide more 
> comments in my code (which I may just do anyway), please feel free to ask 
> me.
>
> Thank you,
>    -- Keeler
>

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