#1314: graphs: calculate tutte polynomial
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Reporter: jason | Owner: rlm
Type: enhancement | Status: new
Priority: major | Milestone: sage-wishlist
Component: graph theory | Resolution:
Keywords: | Work issues:
Report Upstream: N/A | Reviewers:
Authors: | Merged in:
Dependencies: | Stopgaps:
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Comment (by jeremy.l.martin):
Replying to [comment:12 mhansen]:
> I had some old code from awhile back for computing this which I've
attached, along with some commented out possible optimizations. I think I
remember when doing this in practice, avoiding copying the graph saved
quite a bit of time (hence the unmerge function).
mhansen, thanks for sharing this code. Unfortunately, it does not seem to
give the right answer for K_4:
sage: G = graphs.[wiki:CompleteGraph](4); G.allow_loops(true);
G.allow_multiple_edges(true); tp = tutte_polynomial(G,x,y); tp
x^2^*y^2^ + x*y^3^ + x^3^ + x^2^*y + x*y^2^ + x^2^ + x*y
The actual Tutte polynomial of K4 is x^3^ + 3*x^2^ + y^3^ + 4*x*y + 3*y^2^
+ 2*x + 2*y.
I currently do not see a way to implement the Tutte polynomial without
making lots of copies of graphs, but maybe someone else can.
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/1314#comment:13>
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