4sr is an extension of 4store where we are implementing backward chained reasoning. Currently a subset of RDFS is supported. This set includes: rdfs:subClassOf, rdfs:subPropertyOf, rdfs:domain and rdfs:range.
S. Schoenmackers, O. Etzioni, and D. Weld. EMNLP '08: Proceedings of the Conference on Empirical Methods in Natural Language Processing
, page 79--88. Morristown, NJ, USA, Association for Computational Linguistics, (2008)