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.Tue, 21 Aug 2018 13:01:42 +0200How can I compute the minimal fixing set?https://ask.sagemath.org/question/43433/how-can-i-compute-the-minimal-fixing-set/Having the automorphism group Aut(G) of graph G, what is the minimal set of nodes S where each automorphism in Aut(G) contains at least one of the nodes in a set S?
For small graphs it could be computed without using Sage or any other programming. However, for large graphs, writing a piece of code is necessary.ASHTue, 21 Aug 2018 13:01:42 +0200https://ask.sagemath.org/question/43433/Help with graphshttps://ask.sagemath.org/question/43261/help-with-graphs/ I am trying to find the set of (surjective) homomorphic images of the Groetzsch Graph - G. I have two ideas, but I am stuck at both. Help with either would be very much appreciated.
1.I try narrowing down the candidate homomorphic images to graphs with chromatic number at least 4 and number of vertices at most 10 in house of graphs. Then i get a graph6 file and try to check if each of those graphs is a homomorphic image of G. This doesn't work because I don't know how exactly to import the graph6 file into sage.
2. Find the independent sets of G and find all the ways I can combine them into homomorphic images. I' ve heard that this is possible, but seems like a rather daunting task for me because I am very new with sage.glavunchoMon, 06 Aug 2018 09:45:32 +0200https://ask.sagemath.org/question/43261/