VentureBeat – What are graph database query languages?

AllegroGraph was covered in this VentureBeat Article:

AllegoGraph stores RDF-style graphs that can be queried with SPARQL and RDFS++, as well as with programming language extensions like Prolog, a logic programming language, and Allegro Common LISP. Their knowledge graph explorer, Gruff, runs in browsers for visual querying. The product is available for local installation and in clouds like AWS.