Everything is fine
sage: graphs.GrayGraph().diameter()
6
sage: graphs.FosterGraph().diameter()
8
If you define a graph with a variable called Gamma and then call a
method of *another* variable G then do not expect to get the answer to a
property of Gamma...
Vincent
On 02/10/15 19:01, David Joyner wrote:
Simllar problem with the Gray graph:
sage: Gamma = graphs.GrayGraph()
sage: G.diameter()
8
(it should be 6)
G = graphs.LCFGraph(54, [-25,7,-7,13,-13,25], 9)
sage: G.diameter()
6
seems to be the Gray graph
On Fri, Oct 2, 2015 at 5:47 PM, David Joyner <[email protected]> wrote:
On Fri, Oct 2, 2015 at 5:44 PM, David Joyner <[email protected]> wrote:
Hi all:
Several online sources (including a page on Royle's website) give the
girth of the Foster graph to be 10, but Sage gives 6:
sage: Gamma = graphs.FosterGraph()
sage: G.girth()
6
Is there a bug in girth?
- David
I might have found an answer to my own question:
sage: G = graphs.LCFGraph(90, [17,-9,37,-37,9,-17], 15)
sage: G.is_vertex_transitive()
True
sage: G.is_hamiltonian()
True
sage: G.chromatic_number()
2
sage: G.is_bipartite()
True
sage: len(G.vertices())
90
sage: len(G.edges())
135
sage: G.girth()
10
These suggest that G is the true Foster graph
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