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Evaluating Regular Path Queries on Compressed Adjacency Matrices

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Diego Arroyuelo, Adrián Gómez-Brandón, and
Gonzalo Navarro

Regular Path Queries (RPQs), which are essentially regular expressions to be
matched against the labels of paths in labeled graphs, are at the core of
graph database query languages like SPARQL. A way to solve RPQs is to
translate them into a sequence of operations on the adjacency matrices of each
label. We design and implement a Boolean algebra on sparse matrix
representations and, as an application, use them to handle RPQs. Our baseline
representation uses the same space as the previously most compact index for
RPQs and excels in handling the hardest types of queries. Our more succinct
structure, based on *k^2*-trees, is 4 times smaller and still solves complex RPQs in reasonable time.