ITR: A grammar-based graph compressor supporting fast neighborhood queries

Neighborhood queries are the most common queries on graphs; thus, it is desirable to answer them efficiently on compressed data structures. We present a compression scheme called Incidence-Type-RePair (ITR) for graphs with labeled nodes and labeled edges based on RePair and apply the scheme to RDF graphs. We show that ITR speeds up neighborhood queries to only a few milliseconds and thereby outperforms existing solutions while providing a compression size comparable to existing RDF graph compressors.