salam's profile - activity

A graph is called twin-free if distinct vertices have different neighborhoods. I have no idea how to obtain twin-free graphs in Sagemath. Would please you help me?

@John Palmieri, Yes, the natural way is to obtain the neighborhoods of any two vertices and compare them. To find an opt

@John Palmieri, thank you. I know that function but let G=graphs.CompleteBipartiteGraph(2,2); I would like to know i

@John Palmieri, thank you. I know that function but let G=graphs.CompleteBipartiteGraph(2,2); I would like to know i

twin free graphs A graph is called twin-free if distinct vertices have different neighborhoods. I have no idea how to ob

Factor-critical graph I want to check that a graph is factor-critical or not. I did not find any code to do that, except

Factor-critical graph I want to check that a graph is factor-critical or not. I did not find any code to do that, except

@John, thank you so much.

@ John, thank you so much.

@John, thank you so much.

I want to plot a Cayley graph that its connection set is derangements. I mean https://doc.sagemath.org/html/en/refe...

I wrote this code, but it fails to run.

G = SymmetricGroup(3)
CG = G.cayley_graph(generators = Derangements(3))
CGU = CG.to_undirected()
CGU.show()

Could you please give me help?

Plotting a Cayley graph I want to plot a Cayley graph that its connection set is derangements. I mean https://doc.sagema

I know how to find the independence number in graphs in sagemath. I want to obtain a new parameter called $k$-independence number in graphs which means the maximum size of a set of vertices at pairwise distance greater than $k$.

Would you please tell me how I can find this parameter in a graph?

Thank you.

@vdelecroix Thanks, if I want to do this for several times, I checked the following code, but it didn't work

for i in range(5):
point2d(random_matrix(ZZ, 10, 10, x=0, y=2).charpoly().roots(CDF, False), size=50)

Is it correct?

Would you please tell how I can define a random matrix whose entries are 1, 0 and plot its eigenvalues in the complex plane?

@slelievre, Thank you. If I want to contract edges between the tree and Petersen graphs, what codes should be inserted?

I would like to define a graph G as follows:

Assume T is a graph with t leaves. Add t copies of Petersen graph to T and identify a vertex from the outer cycle of each Petersen graph with a leaf such that t added Petersen graphs are disjoint.

I would appreciate it if you tell how I can define this graph.

@tmonteil, Thanks, I think it works, but I do not know how to write the code

@tmonteil, I know how to find the matching number, but I am looking for the induced matching https://en.wikipedia.org/wiki/Induced...

An induced matching in a graph G is a set of edges, no two of which meet a common node or are joined by an edge of G; that is, an induced matching is a matching which forms an induced subgraph.

Would you please tell me how I can find the max induced matching in a graph?