In such cases, the fastest known shortest-path algorithm doesn’t work. For decades, fast algorithms for finding shortest paths on negative-weight graphs have remained elusive.

In undirected graphs, every link can be traversed in both directions. Computer scientists are usually more interested in the broader class of graphs that feature one-way paths, but these “directed” ...

In directed graphs, relationships are asymmetric and these asymmetries contain essential structural information about the graph. Directed relationships lead to a new type of clustering that is not ...