L-reach: A vertex set cover approach to regular expression-based reachability queries

It is very common that we can find edge-labeled graphs in many applications. And one of the most important issues is regular expression-based reachability query, i.e., to test if one vertex u has a path to another vertex v and the path labels are constrained by a regular expression. Exiting indices for processing classic reachability queries are not fit for processing this kind of operation. In this paper, we study the problem of constructing a new index framework to preserve the path label information for edge-labeled graphs in acceptable size. Our index is based on the concept of minimum vertex cover approximation. We also give the algorithm for regular expression-based queries. The experimental results on real and synthetic datasets show that our algorithm is more efficient than the state-of-the-art methods in time and space.