Sagemath saving results

[Mauro Weber]

Hello, I’m using Sagemath to filter some specific graphs from the general graphs using these codes: 

“I = graphs(n)

for G in I:

if G.is_tree():

if (G.cartesian_product(G)).matching(value_only = True) == n*n/2:

G.show()”

The problem is that there are a large number of graphs to filter particularly when the number of vertices is greater than 16. This takes a long time so. I was wondering if it is possible to create a library with those graphs I received from the code. Then every time I need to use those graphs I can get them from the library and don’t need to run the code all over again.

[Vincent Delecroix]

Le 06/05/2020 à 00:10, Mauro Weber a écrit :
> for G in I:
>
> if G.is_tree():

If you want to iterate over trees don't filter them by generating all
graphs. This is a huge waste of time

# graphs(n) "=" 2^(n^2) / n!
# trees(n) "=" Catalan(n)

Trees are easy to generate up to isomorphism.

Vincent

[Dima Pasechnik]

On Thu, May 7, 2020 at 11:38 AM Vincent Delecroix

specifically, see
http://doc.sagemath.org/html/en/reference/graphs/sage/graphs/trees.html

>
> Vincent
>
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