lcz

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1 years, 140 days

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These are questions asked by lcz

   It would seem that the option style = planar  of DrawGraph()    is  failure when some graphs are planar.
   For example: 

treeof5:=[NonIsomorphicGraphs(5,4,output= graphs,outputform=graph,restrictto = connected )]:
DrawGraph ~ (treeof5, stylesheet=[vertexborder=false,vertexpadding=20]);


 

We know tree is planar graph obviously. But when I add the option style = planar ,  drawing of the first tree of list displays an error :
Error, (in GraphTheory:-Graph) vertex 1 cannot be its own neighbour in list of neighbours

I did not find any reason to explain. 

         I'd like to draw a graph with its  vertices  of 3d style.  Just like following image:

  

  I did not find the desired choices for this graph.

In graph theory, the crossing number cr(G) of a graph G is the lowest number of edge crossings of a plane drawing of the graph G. I'd like to use maple to compute crossing number of some graphs (any graphs is ok,  for example: cr(K5)=1 ). Someone can help me ? thanks. 

I know the problem of computing the crossing number is NP, but I guess we have some good  ways to compute in some small graphs.

 I'd like to get all at most 15 vertices Non-isomorphic  connected  bipartite graphs. One way is to use the function NonIsomorphicGraphs(k, output = graphs, outputform = graph, restrictto = connected).

with(GraphTheory):

k:=8;
s1:=[NonIsomorphicGraphs(k,restrictto = connected,output=graphs,outputform=graph)]:
bipartitegraph:=select[flatten](x->IsBipartite(x)=true, s1):
nops(bipartitegraph);

But when k=9, it is slow, I doubted that the code 

By Checking out the encyclopedia,http://oeis.org/A033995 , we knew the following number of bipartite graphs datas of , at most 14, they are not many(the datas contain  no-connected conditions)

 

so I read the help document about  

awesome.

Ps: I know  in SageMath  we can get all bipartite graphs quikly even though n>=10  by  using the 

for g in graphs.nauty_geng('-c -b 10 -g'):
 
But I hope it can be realized in Maple. 

Thanks!

 

I got a list containing all non isomorphic connected graphs with 6 vertices. Total number of the list members is 112 , and they are not too many . So I want to draw them all . It is good for Maple worksheet .
 
In order to save it and print it out on paper, I import it as pdf form . But the problem is that every page in pdf only contains 8 graphs . It wastes wasted too many spaces. It is unreasonable . I want to draw 20-30 graphs in one page of pdf. What is the solution to my problems? Thanks in advance. This problem has puzzled me for a long time.

with(GraphTheory):
s1:=[NonIsomorphicGraphs(6,restrictto = connected,output=graphs,outputform=graph)]:
DrawGraph~(s1);

 

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