directed-graph

I came upon wait-for graphs and I wonder, are there any efficient algorithms for detecting if adding an edge to a directed graph results in a cycle? The graphs in question are mutable (they can have nodes and edges added or removed). And we're not interested in actually knowing an offending cycle, just knowing there is one is enough (to prevent adding an offending edge). Of course it'd be possible to use an algorithm for computing strongly connected components (such as Tarjan's) to check if the new graph is acyclic or not, but running it again every time an edge is added seems quite

How do I check if a directed graph is acyclic? And how is the algorithm called? I would appreciate a reference. FryGuy I would try to sort the graph topologically , and if you can't, then it has cycles. Doing a simple depth-first-search is not good enough to find a cycle. It is possible to visit a node multiple times in a DFS without a cycle existing. Depending on where you start, you also might not visit the entire graph. You can check for cycles in a connected component of a graph as follows. Find a node which has only outgoing edges. If there is no such node, then there is a cycle. Start a

In the DOT language for GraphViz , I'm trying to represent a dependency diagram. I need to be able to have nodes inside a container and to be able to make nodes and/or containers dependent on other nodes and/or containers. I'm using subgraph to represent my containers. Node linking works just fine, but I can't figure out how to connect subgraphs. Given the program below, I need to be able to connect cluster_1 and cluster_2 with an arrow, but anything I've tried creates new nodes instead of connecting the clusters: digraph G { graph [fontsize=10 fontname="Verdana"]; node [shape=record fontsize