ASKSAGE: Sage Q&A Forum - Latest question feedhttp://ask.sagemath.org/questions/Q&A Forum for SageenCopyright Sage, 2010. Some rights reserved under creative commons license.Fri, 19 Oct 2018 04:29:29 -0500Is there anything in Sage which solves #SAT ?http://ask.sagemath.org/question/43984/is-there-anything-in-sage-which-solves-sat/For example using [sharpsat](https://sites.google.com/site/marcthurley/sharpsat) or relsat or Dsharp?SébastienFri, 19 Oct 2018 04:29:29 -0500http://ask.sagemath.org/question/43984/How to find the spanning elementary subgraphs of a given graphhttp://ask.sagemath.org/question/43581/how-to-find-the-spanning-elementary-subgraphs-of-a-given-graph/consider the following definition: A subgraph $H$
of a graph
$G$
is called an elementary subgraph if each component of
$H$
is either an edge (
$K_{2}$
) or a
cycle of length at least
$3$. A spanning elementary subgraph is a subgraph having all components either path(i.e. $K_{2}$) or cycles and verex set is same as those of $G$. for example consider the graph $C_{4}$ with $V(G)$={1,2,3,4}. then it has 3 spanning elementary subgraphs two edge components namely {12,34};{14,23} and the whole cycle itself.The cycle is named in anticlockwise direction.
Now my problem is:
Consider the following code:
G=graphs.EmptyGraph()
G.add_edges([(1,2),(2,3),(3,4),(4,5),(5,1),(6,5),(6,8),(8,9),(7,9),(7,6),(7,10),(10,11),(10,12),(11,12)])
G.show()
Can we have a sage code that gives all possible spanning subgraphs of this graph.KuldeepTue, 04 Sep 2018 08:02:42 -0500http://ask.sagemath.org/question/43581/How can I compute the minimal fixing set?http://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 automporphism 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 06:01:42 -0500http://ask.sagemath.org/question/43433/Help with graphshttp://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 02:45:32 -0500http://ask.sagemath.org/question/43261/can you find the total chromatic number (edge and vertices) of a graph?http://ask.sagemath.org/question/35744/can-you-find-the-total-chromatic-number-edge-and-vertices-of-a-graph/I' m trying to find the total chromatic number of a graph and I was wondering if anyone knew how to do this? I have found the edge and vertex chromatic number but am unable to join the 2. livvy94Sat, 26 Nov 2016 08:00:14 -0600http://ask.sagemath.org/question/35744/Model of polynomial with integer coefficientshttp://ask.sagemath.org/question/10321/model-of-polynomial-with-integer-coefficients/Can Sage find fit to the data in form of the polynomial with integer coefficients? I mean that I want to find polyinomial with integer coefficients which will approximate my date by the best way, that is the distance from points in "mydata" to graph of the polyinomial will be the least.
Now I have:
...
mydata = [[A[i],B[i]] for i in range(0,len(A))]
var('a,b,c,x,t')
def intPol(a,b,c,x):
f=a*x^2 + b*x + c
return f
myfit = find_fit(mydata,intPol,parameters = [a, b, c], variables = [x],solution_dict=True)
Is there any way to approximate my data by same polynomial without models?
Sorry for my English(bakantThu, 04 Jul 2013 21:24:14 -0500http://ask.sagemath.org/question/10321/