Time- and Space-Efficient Regular Path Queries

We introduce a time-and space-efficient technique to solve regular path queries over labeled graphs. We combine a bit-parallel simulation of the Glushkov automaton of the regular expression with the ring index introduced by Arroyuelo et al., exploiting its wavelet tree representation of the triples in order to efficiently reach the states of the product graph that are relevant for the query. Our query algorithm is able to simultaneously process several automaton states, as well as several graph nodes/labels. Our experimental results show that our representation uses 3-5 times less space than the alternatives in the literature, while generally outperforming them in query times (1.67 times faster than the next best).