An External Memory Algorithm for All-Pairs Regular Path Problem

In this paper, we consider solving the all-pairs regular path problem on large graphs efficiently. Let G be a graph and r be a regular path query, and consider finding the answers of r on G. If G is so small that it fits in main memory, it suffices to load entire G into main memory and traverse G to find paths matching r. However, if G is too large and cannot fit in main memory, we need another approach. In this paper, we propose an external memory algorithm for solving all-pairs regular path problem on large graphs. Our algorithm finds the answers matching r by scanning the node list of G sequentially, which avoids random accesses to disk and thus makes regular path query processing I/O efficient.