LichengZhang

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These are questions asked by LichengZhang

   I need to integrate x with a<=x<=b and k , l are constants.

I input foolowing code , it did not work. Maybe you have some good ideas to solve this! thanks!

int(sqrt(1+((k*Pi)/l*cos((Pi*x)/l))^2), x = a.. b) assuming x>=a, x<=b

   I download one  file about  all 5 connected graphs of graph6  (total 21 graphs). format from http://users.cecs.anu.edu.au/~bdm/data/graphs.html,and I want to import it in Maple. Since platform restrictions , I can not attach the file .   Please download it by yourself,very thanks to you ! 

   I put the file  in the installation path of  Maple in my computer:D:\\ Program Files\Maple 2019. (my computer system is Window 10 )  And I import it like following: 

  But it  only imports the graph of  the first row in the file. How to import all graphs in a file of graph6 format one time?

 

   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.

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