Given the adjacency matrix of a graph, I need to obtain the chromatic number (minimum number of colours needed to paint every node of a graph so that adjacent nodes get different colours). Preferably it should be a java algorithm, and I don't care about performance. Thanks. Edit: recently introduced a fix so the answer is more accura...
I've been looking for an implementation (I'm using networkx library.) that will find all the minimum spanning trees (MST) of an undirected weighted graph. I can only find implementations for Kruskal's Algorithm and Prim's Algorithm both of which will only return a single MST. I've seen papers that address this problem (such as Represen...
Hi, in words, can someone post directions towards finding the 'maximal' independent set in a simple graph? I read up something from ETH site which said one can find such in O(n) by simply picking a random vertex v and than scanning the rest and attempting to find if there's an edge from v to the rest. Thanks ...
First of all, let me say I'm using LyX, though I have no problem using ERT. Secondly, what is the most simplest way to draw a simple graph like this in Latex? I've seen some documents with graphs and I've seen some examples, but I couldn't figure out how to just draw a simple graph - what packages do I need, etc? ...
I would like to know a fast algorithm to find only the clique number(without actually finding the clique) of a graph with about 100 vertices. I am trying to solve the following problem. http://uva.onlinejudge.org/external/1/193.html ...
I want to use the apparently fantastic GraphSharp library but the project has NO documentation. Specifically I'm interested in using the layout engine and not interested in the WPF control. I simply want to calculate a layout (positions of the nodes) for a given graph and layout algorithm. Does anyone have any advice, tips, links on h...
While this may look like homework, I assure you it's not. It stems from some homework assignment I did, though. Let's call an undirected graph without self-edges "cubic" if every vertex has degree exactly three. Given a positive integer N I'd like to generate a random cubic graph on N vertices. I'd like for it to have uniform probabilit...
Suppose you have a set of nodes connected into a tree structure with one root node and any node may have any number of child nodes. You can only traverse the tree starting at the root node or from your current position along direct connections. I.e., no random access to a specific node, but the structure of the graph is already known an...
Hi, I want to find all the cycles in a directed graph. Starting Depth-first search from one node will find some cycles(finding back-edges). So, i applied dfs to all the nodes in the graph(i.e. each time the root is a different node). I am able to get all the cycles using this(by eliminating duplicate ones). But, i am not sure whether thi...
My girlfriend got this question in an interview, and I liked it so much I thought I'd share it... Write an algorithm that receives a dictionary (Array of words). The array is sorted lexicographically, but the abc order can be anything. For example, it could be z, y, x, .., c, b, a. Or it could be completely messed up: d, g, w, y, ... It ...
Hello everyone, I know this question is more of a discussion than an actual question but I believe some results could come up by listening to other people's opinions. I was wondering if there's any point in visualizing multigraphs. I mean is there a practical application in which you'd actually want a multigraph visualized and in extend...
ISGCI lists a lot of graph classes, many of which are recognizable in polynomial time. Is anyone here aware of actual implementations of these algorithms? ...
The diagram shown on this link of the "A graph with 6 vertices and 7 edges where the vertex no 6 on the far-left is a leaf vertex or a pendant vertex." has DIAMETER 4? right or wrong? Definitions are The diameter of a graph is the maximum eccentricity of any vertex in the graph. That is, it is the greatest distance between any...
I have a very, very large graph, and I want to find the shortest path from one vertex to another. The graph is directed and unweighted. I have considered using some modification of Dijkstra's algorithm, but I usually use that for weighted undirected graphs. So then my other thought was to use a DFS, since I can treat all the weights ...
What is the most efficient way to generate a large (~ 300k vertices) random planar graph ("random" here means uniformly distrbuted)? ...
Can some one tell me the difference between Hamiltonian path and euler path. Both seems similar! Thanks & Regards, Mousey ...
Is there any applicable approach to find two disjoint spanning trees of an undirected graph or to check if a certain graph has two disjoint spanning trees ...
Consider a set of points arranged on a grid of size N-by-M. I am trying to build the adjacency matrix such that neighboring points are connected. For example, in a 3x3 grid with a graph: 1-2-3 | | | 4-5-6 | | | 7-8-9 We should have the corresponding adjacency matrix: +---+------------------------------------------------------+ | |...
Hello, I have a directed cyclic graph with more than one cycle in it and I need a way to detect (and list) each cycle present in the digraph. The graph can be seen here: http://img412.imageshack.us/img412/3327/schematic.gif This is a dummy graph put together for the sake of debugging my python script. It contains the cycles: [n13, n14...
These questions regard a set of data with lists of tasks performed in succession and the total time required to complete them. I've been wondering whether it would be possible to determine useful things about the tasks' lengths, either as they are or with some initial guesstimation based on appropriate domain knowledge. I've come to thin...