Joint Workshop on Scalable and High-Performance Semantic Web Systems (SSWS + HPCSW 2012) At the 11th International Semantic Web Conference (ISWC2012), Boston, USA, November, 2012 SSWS + HPCSW 2012 PC Co-chairs’ Message For 2012, the 8th International Workshop on Scalable Semantic Web Knowledge Base Systems (SSWS2012) and the 2nd Workshop on High-Performance Com- puting for the Semantic Web (HPCSW2012) were merged together. This joint workshop focused on addressing broader scalability issues with respect to the development and deployment of knowledge base systems on the Semantic Web. Typically, such systems deal with information described in Semantic Web lan- guages like OWL and RDF(S), and provide services such as storing, reasoning, querying and debugging. There are two basic requirements for these systems. First, they have to satisfy the application’s semantic requirements by provid- ing sufficient reasoning support. Second, they must scale well in order to be of practical use. Given the sheer size and distributed nature of the Semantic Web, these requirements impose additional challenges beyond those addressed by earlier knowledge base systems. This workshop brought together researchers and practitioners to share their ideas regarding building and evaluating scalable knowledge base systems for the Semantic Web. This year we received 11 submissions. Each paper was carefully evaluated by three workshop Program Committee members. Based on these reviews, we accepted seven papers for presentation. We sincerely thank the authors for all the submissions and are grateful for the excellent work by the Program Committee members. November 2012 Achille Fokoue Thorsten Liebig Eric Goodman Jesse Weaver Jacopo Urbani David Mizell Program Committee Jans Aasman Anastasios Kementsietsidis Franz, Inc. IBM Watson Research Center, USA Robert Adolf Pavel Klinov Pacific Northwest Nat. Lab., USA Ulm University, Germany Sinan Al-Saffar Spyros Kotoulas Pacific Northwest Nat. Lab., USA IBM Watson Research Center, USA Alexey Cheptsov Thorsten Liebig High Performance Computing Center derivo GmbH, Germany Stgt, Germany David Mizell Oscar Corcho YarcData, Inc, USA Univ. Politecnica de Madrid, Spain Ralf Möller Mike Dean Hamburg Univ. of Techn., Germany BBN Technologies, USA Jeff Z. Pan Achille Fokoue University of Aberdeen, UK IBM Watson Research Center, USA Axel Polleres Raúl Garcı́a-Castro Siemens AG, Österreich Univ. Politecnica de Madrid, Spain Mariano Rodriguez Eric Goodman Free University of Bolzano, Italy Sandia National Laboratories, USA Sebastian Rudolph Yuanbo Guo Karlsruhe Inst. of Techn., Germany Microsoft, USA Andy Seaborne Volker Haarslev Epimorphics, UK Condordia University, Canada Kavitha Srinivas David Haglin IBM Watson Research Center, USA Pacific Northwest Nat. Lab., USA Jacopo Urbani Pascal Hitzler Vrije Universiteit Amsterdam, Nether- Wright State University, Ohio, USA lands Aidan Hogan Jesse Weaver DERI Galway, Ireland Rensselaer Polytechnic Institute, USA Bill Howe Gregory Todd Williams University of Washington, USA Rensselaer Polytechnic Institute, USA Cliff Joslyn Takahira Yamaguchi Pacific Northwest Nat. Lab., USA Keio University, Japan Additional Reviewers Cong Wang Kevin Lee Wright State University, Ohio, USA University of Aberdeen, UK Table of Contents FishMark: A Linked Data Application Benchmark . . . . . . . . . . . . . . . . . . . . 1 Samantha Bail, Sandra Alkiviadous, Bijan Parsia, David Workman, Mark van Harmelen, Rafael S. Gonçalves and Cristina Garilao The Combined Approach to OBDA: Taming Role Hierarchies using Filters 16 Carsten Lutz, Inanç Seylan, David Toman and Frank Wolter Evaluation of Query Rewriting Approaches for OWL 2 . . . . . . . . . . . . . . . . 32 Héctor Pérez-Urbina, Edgar Rodrı́guez-Dı́az, Michael Grove, George Konstantinidis and Evren Sirin Triangle Finding: How Graph Theory can Help the Semantic Web . . . . . . . 45 Eric Goodman and Edward Jimenez Cascading Map-Side Joins over HBase for Scalable Join Processing . . . . . . 59 Alexander Schätzle, Martin Przyjaciel-Zablocki, Christopher Dorner, Thomas Hornung and Georg Lausen Scalable Nonmonotonic Reasoning over RDF data using MapReduce . . . . 75 Ilias Tachmazidis, Grigoris Antoniou, Giorgos Flouris and Spyros Kotoulas A Scalability Metric for Parallel Computations on Large, Growing Datasets (like the Web) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 Jesse Weaver