ASKSAGE: Sage Q&A Forum - RSS feedhttps://ask.sagemath.org/questions/Q&A Forum for SageenCopyright Sage, 2010. Some rights reserved under creative commons license.Sat, 27 Mar 2021 03:55:43 +0100Find 25-vertex 4-regular planar graphs using plantrihttps://ask.sagemath.org/question/56405/find-25-vertex-4-regular-planar-graphs-using-plantri/I am using SageMath 9.2 and I have recently wanted to add the optional package **plantri**.
I found a link to a similar question before:
[Ask Sage question 52358](https://ask.sagemath.org/question/52358)
where a comment suggests this command:
sage: !sage -i plantri
An error occurred during the installation process that prevented it from proceeding.
make[3345]: Entering directory '/opt/sagemath-9.2'
0 [main] make (45584) C:\Users\asus\AppData\Local\SageMath 9.2\runtime\bin
\make.exe: *** fatal error in forked process - ccalloc would have returned NULL
0 [main] make 15063 dofork: child -1 - forked process 45584 died unexpect
dly, retry 0, exit code 0xC0000142, errno 11
make[3345]: *** [Makefile:31: bootstrap] Error 127
My computer runs the Windows10 64-bit operating system.
I don't know how to solve this installation problem.
In fact, the graph theory problem I encountered is as follows.
I 'd like to generate all **25-vertex 4 regular planar graphs that size of maximum face is 4**.
Of course it may not exist.
With the help of plantri, I think there should be no problem,
because I saw [James Preen's page on the degree-diameter problem](http://faculty.capebretonu.ca/jpreen/degdiam.html),
which contains the following paragraph.
> Additionally, using plantri it has been established that there exist
> **no 4-regular planar graphs with 28** vertices and similarly
> there are no 3-regular planar graphs with diameter 4 with
> between 20 and 30 vertices.
If someone has successfully installed it, can you help me see if there is such a graph?
Thanks in advanceļ¼
sage: for G in graphs.planar_graphs(25, minimum_degree=4):
....: if G.num_edges==50:
sage: show(G)
sage: print("nofind")
The above codes may need improvement.lichengSat, 27 Mar 2021 03:55:43 +0100https://ask.sagemath.org/question/56405/