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Education

2007–2013
Rensselaer Polytechnic Institute
Ph.D. in Computer Science
Ph.D. in Computer Science, specializing in scalable query answering on the Semantic Web. Designed, implemented, and evaluated a federated query answering system for SPARQL queries able to automatically improve query results through iterative query plan expansion based on the discovery of new, relevant data sources.
2006–2007
University of Maryland
Ph.D. coursework in Computer Science
2001–2003
Wheaton College
B.A. Computer Science, Philosophy Minor
Graduated with Departmental Honors, Magna cum laude
1998–2000
Santa Monica College

Experience

2020–
Amazon Web Services, Seattle, WA
Senior Software Development Engineer
Implemented and maintained the cost-based statistics component of the Neptune graph database, supporting planning and optimization of SPARQL and OpenCypher queries. Designed and implemented cost-based statistics and query-plan components as part of the development of the Neptune Analytics graph database, taking this work from design through product release. Designed extensions to the SPARQL query language to support interoperability with the Property Graph data model.
2019–2020
J. Paul Getty Trust, Los Angeles, CA
Senior Data Engineer
Designed and implemented data pipeline for producing semantically enriched art sales, provenance, and publications data from legacy systems. Collaborated with domain experts to ensure both fidelity of data and that the resulting data model would serve research needs. The resulting data conformed to the linked.art profile of CIDOC-CRM, and used JSON-LD to allow use by tools supporting a wide range of semantic capability, and supporting research by consumers with varied needs.
2015–2018
Hulu, Santa Monica, CA
Software Developer
Designed, implemented, and maintained a meta-query planning tool responsible for processing high-level analytical queries, selecting an appropriate data source, and generating a structured query to fully answer the user's query. The system was designed to work efficiently with complex inputs and over an extensible, wide range of available databases including Hive, Presto, Impala, and MySQL, and generate optimized queries over hundreds of terabytes of data.
2014–2015
Pacific Northwest National Laboratory, Richland, WA
Consultant
Designed and implemented a SPARQL query planning and optimization system used in conjunction with existing massively parallel graph database system.
2011
O'Reilly Media, Inc., Sebastopol, CA
Consultant
Reviewed existing use of semantic web technology and data and provided guidance on its continued use in critical business functions. Implemented tools to allow data exchange between existing RDF, relational, and document databases.
2005–2006
Wheaton College Genomics Research Group, Norton, MA
Consultant
Consulted on the creation of an introductory programming textbook for biology researchers. Oversaw the technical aspects of authoring Perl code meant for diverse, cross-platform use by novices, and insured that included code used the standards and best practices of the Perl community.
2006
Shopzilla, Inc., Los Angeles, CA
Software Engineer
Designed and implemented a site taxonomy server, integrating an existing product taxonomy database with a new REST API for querying and updating an RDF-based data model using SKOS and OWL.
2005
Shopzilla, Inc., Los Angeles, CA
Software Engineer
Redesigned and implemented a merchant statistics reporting tool with a focus on scalability, maintainability, and extensibility. Work involved generating, storing and executing complex queries across multiple Sybase ASE and IQ databases using Trasact-SQL and Perl.
2003–2004
BizRate.com, Los Angeles, CA
Software Engineer
Implemented "related product" search feature, integrating with an existing object-oriented mod_perl front-end. Redesigned and implemented database abstraction, localization, business logic and presentation classes in Perl for use with consumer search site. Worked on maintenance and development of consumer search technologies requiring scalability and efficiency.
2001–2003
Wheaton College Genomics Research Group, Norton, MA
Wheaton Research Fellow
Implemented in C++ and Perl: database code allowing statistical analysis of DNA sequences across genomes; a search engine which correlates search results with existing published literature in PubMed; and a framework for researching motif distributions in targeted genomic regions.
2001–2003
96.5FM Wheaton College Radio, Norton, MA
System Administrator/Webmaster
Administered computers used on a daily basis in running the radio station. Also responsible for updating the station website. Administrative work involved maintaining and upgrading applications and operating systems on desktops, workstations, and servers running Windows 95, 98, 2000, and XP, MacOS 8–9, and Linux.
2001
Wheaton College, Norton, MA
Mars Fellow
Researched surface reconstruction and supporting infrastructure. Designed and implemented an object-oriented, surface reconstruction research environment in C++ using OpenGL and pthreads. Responsible for coordinating the work of two other programmers to produce the final system.
1996–2001
Cnation Inc., Los Angeles, CA
Senior Software Engineer
Acted as a project leader for software development projects and was responsible for managing other developers. Designed and implemented a large, open source, mod_perl based web application framework, "BingoX", and its associated database abstraction and parsing classes, "Data::Query" and "Apache::XPP". Designed and implemented large database driven mod_perl applications for clients.

Published

2024

Michael Schmidt, Brad Bebee, Willem Broekema, Mohamed Elzarei, Carlos Manuel Lopez Enriquez, Marcin Neyman, Florian Schmedding, Andreas Steigmiller, Bryan Thompson, Geo Varkey, Gregory Todd Williams and Amanda Xiang. (2024). openCypher over RDF: Connecting Two Worlds. Proceedings of the ISWC Poster and Demos Track, Baltimore, MD, November 11 2024.

Willem Broekema, Mohamed Elzarei, Ora Lassila, Carlos Manuel Lopez Enriquez, Marcin Neyman, Florian Schmedding, Michael Schmidt, Andreas Steigmiller, Geo Varkey, Gregory Todd Williams and Amanda Xiang. (2024). openCypher Queries over Combined RDF and LPG Data in Amazon Neptune. Proceedings of the ISWC Industry Track, Baltimore, MD, November 11 2024.

Olaf Hartig, Gregory Todd Williams, Michael Schmidt, Ora Lassila, Carlos Manuel Lopez Enriquez and Bryan Thompson. (2024). Datatypes for Lists and Maps in RDF Literals. Proceedings of the Extended Semantic Web Conference Poster and Demos Track, Hersonissos, Greece, May 26 2024. (Best Poster Award.)

2015

Morari, A., Castellana, V. G., Villa, O., Weaver, J., Williams, G. T., Haglin, D. J., Tumeo, A. and Feo, J. (2015). GEMS: Graph Database Engine for Multithreaded Systems in K. Li, H. Jiang, L. T. Yang and A. Cuzzocrea (Eds.), Big Data: Algorithms, Analytics, and Applications (pp. 139–156). New York, NY: Chapman and Hall/CRC.

2014

Gregory Todd Williams and Kjetil Kjernsmo. (2014). Pushing complexity down the stack. Proceedings of the ISWC Developers Workshop 2014, Riva del Garda, Italy, October 19 2014, online pdf.

2013

Gregory Todd Williams. (2013). Planning and Evaluation of Federated Queries on the Web. Ph.D. thesis, Rensselaer Polytechnic Institute, Troy, New York, March 2013, online pdf.

2011

Gregory Todd Williams and Jesse Weaver. (2011). Enabling fine-grained HTTP caching of SPARQL query results. Proceedings of the 10th International Conference on The Semantic Web (ISWC), Bonn, Germany, October 23 2011, online pdf.

2010

Gregory T. Williams, Jesse Weaver, Medha Atre, and James A. Hendler. (2010). Scalable Reduction of Large Datasets to Interesting Subsets. Journal of Web Semantics: Science, Services and Agents on the World Wide Web, online.

Sibel Adali, Robert Escriva, Mark K. Goldberg, Mykola Hayvanovych, Malik Magdon-Ismail, Boleslaw K. Szymanski, William A. Wallace and Gregory T. Williams. (2010). Measuring Behavioral Trust in Social Networks. Proceedings of IEEE International Conference on Intelligence and Security Informatics (ISI 2010).

2009

Gregory Todd Williams, Jesse Weaver, Medha Atre, and James A. Hendler. (2009). Scalable Reduction of Large Datasets to Interesting Subsets. Winner, Billion Triples Challenge, 8th International Semantic Web Conference, Chantilly, Virginia, October 27 2009, online pdf.

Jesse Weaver and Gregory Todd Williams. (2009). Scalable RDF query processing on clusters and supercomputers. Proceedings of the 5th International Workshop on Scalable Semantic Web Knowledge Base Systems (SSWS), Chantilly, Virginia, November 26 2009, 73-85, online pdf.

2008

Gregory Todd Williams. (2008). Supporting Identity Reasoning in SPARQL Using Bloom Filters. Proceedings of Workshop on Advancing Reasoning on the Web, Tenerife, Spain, June 2 2008, online pdf.

2007

Gregory Todd Williams. (2007). Extensible SPARQL Functions With Embedded Javascript. Proceedings of 3rd Workshop SFSW'07, Innsbruck, Austria, June 6 2007, online pdf.

2005

Gregory Todd Williams. (2005). MT-Redland: An RDF Storage Backend for Movable Type. Proceedings of 1st Workshop SFSW'05, Hersonissos, Greece, May 30 2005, CEUR Workshop Proceedings, ISSN 1613-0073, online pdf.

2004

Betsey D. Dyer, Mark D. LeBlanc, Stephen Benz, Peter Cahalan, Brian Donorfio, Patrick Sagui, Adam Villa and Gregory Williams (2004). A DNA motif lexicon: cataloguing and annotating sequences. In Silico Biology 4,0039(2004).

2003

Gousie, M. B., Williams, G., Agnitti, T., and Doolittle, N. CompSurf: An Environment for Exploring Surface Reconstruction Methods on a Grid. Computers & Geosciences 29, 9(2003), 1165-1173.

2002

Williams, G., Doolittle, N. and Agnitti, T. (2002). A surface reconstruction research environment. The Journal of Computing in Small Colleges,v17(6), 301–302. Presented at the 2002 Northeastern Conference on Computing in Small Colleges, Worcester, MA, April 2002.

LeBlanc, M., Baron, M., Christoforou, A., Doolittle, N., Kimball, M., Villa, A., Williams, G. and Dyer, B. (2002). The DNA Motif Lexicon — cataloguing and annotating genomes. Proceedings of the 14th International Genome Sequencing and Analysis Conference, October 2–5, 2002, Boston, MA, p.92.

Program Committees

Standards Groups

Projects

Designed and implemented a system as part of the data.gov project to convert open governmental data from tabular formats to RDF, allowing iterative enhancement of data including schema mapping and recording of maximal data provenance.

Designed and implemented the open source Kineo SPARQL system for Swift. Based on trait-based design and lessons learned in the Attean project, Kineo is a research platform for exploring new approaches to implementing and extending SPARQL.

Designed and implemented the Attean, RDF::Query, and , RDF::Trine RDF frameworks and query engines for Perl. RDF::Query was one of the initial 14 implementations of SPARQL as it was published as a W3C Recommendation in 2008, and was one of the first system to fully support the SPARQL 1.1 Query, Update, Service Description, and Protocol standards in 2013.