Vasileios Efthymiou
Assistant Professor
Research Field: Database Systems for Big Data
Email:
CV
Vasilis Efthymiou is an Assistant Professor at the Department of Informatics and Telematics, Harokopio University of Athens. He received his Ph.D. degree in 2017 from the Computer Science Department, University of Crete, for his research on entity resolution in the Web of Data.
Prior to his current appointment, he was a Postdoctoral Researcher at IBM Research – Almaden and at FORTH-ICS, where his work focused on data management and AI for natural language interfaces to data. He also served as a research intern at the IBM T.J. Watson Research Center (NY, USA), specializing in matching Web tables to Knowledge Graphs. He has co-authored two books, more than 60 peer-reviewed articles, and co-invented 4 US patents.
Since 2025, he has been serving as the Coordinator of the W3C Greek Office. His professional service includes co-organizing the SemTab challenge at ISWC and the TaDA workshop at VLDB. He is currently the General Co-chair of HDMS 2026, the Web Chair of EDBT/ICDT 2026, and the Local Arrangements Chair of VLDB 2027.
Prior to his current appointment, he was a Postdoctoral Researcher at IBM Research – Almaden and at FORTH-ICS, where his work focused on data management and AI for natural language interfaces to data. He also served as a research intern at the IBM T.J. Watson Research Center (NY, USA), specializing in matching Web tables to Knowledge Graphs. He has co-authored two books, more than 60 peer-reviewed articles, and co-invented 4 US patents.
Since 2025, he has been serving as the Coordinator of the W3C Greek Office. His professional service includes co-organizing the SemTab challenge at ISWC and the TaDA workshop at VLDB. He is currently the General Co-chair of HDMS 2026, the Web Chair of EDBT/ICDT 2026, and the Local Arrangements Chair of VLDB 2027.
Selected Publications
- V. Christophides, V. Efthymiou, K. Stefanidis. Entity Resolution in the Web of Data. Synthesis Lectures on The Semantic Web: Theory and Technology, Morgan and Claypool (2015)
- A. Quamar, V. Efthymiou, C. Lei, F. Özcan: Natural Language Interfaces to Data. Foundations and Trends in Databases 11(4): 319-414 (2022)
- L. Zecchini, V. Efthymiou, F. Naumann, G. Simonini. Deduplicated Sampling On-Demand. PVLDB 18(8): 2482-2495 (2025)
- G. Papadakis, V. Efthymiou, E. Thanos, O. Hassanzadeh, P. Christen. An Analysis of One-to-One Matching Algorithms for Entity Resolution. VLDBJ 32(6): 1369-1400 (2023)
- N. Fanourakis, V. Efthymiou, D. Kotzinos, V. Christophides. Knowledge Graph Embedding Methods for Entity Alignment: An Experimental Review. Data Mining and Knowledge Discovery 37(5): 2070-2137 (2023)
- V. Christophides, V. Efthymiou, T. Palpanas, G. Papadakis, K. Stefanidis. An Overview of End-to-End Entity Resolution for Big Data. ACM Computing Surveys 53(6): 127:1-127:42 (2021)
- A. Vretinaris, C. Lei, V. Efthymiou, X. Qin, F. Özcan. Medical Entity Disambiguation using Graph Neural Networks. SIGMOD 2021
- S. Ahmetaj, V. Efthymiou, R. Fagin, P. Kolaitis, C. Lei, F. Özcan, L. Popa. Ontology-Enriched Query Answering on Relational Databases. IAAI 2021
- J. Hao, C. Lei, V. Efthymiou, A. Quamar, F. Özcan, Y. Sun, W. Wang. MEDTO: Medical Data to Ontology Matching using Hybrid Graph Neural Networks. KDD 2021
- J. Sen, C. Lei, A. Quamar, F. Özcan, V. Efthymiou, A. Dalmia, G. Stager, A. Mittal, D. Saha, K. Sankaranarayanan. ATHENA++: Natural Language Querying for Complex Nested SQL Queries. PVLDB 13(11): 2747-2759 (2020)
- A. Quamar, V. Efthymiou, C. Lei, F. Özcan: Natural Language Interfaces to Data. Foundations and Trends in Databases 11(4): 319-414 (2022)
- L. Zecchini, V. Efthymiou, F. Naumann, G. Simonini. Deduplicated Sampling On-Demand. PVLDB 18(8): 2482-2495 (2025)
- G. Papadakis, V. Efthymiou, E. Thanos, O. Hassanzadeh, P. Christen. An Analysis of One-to-One Matching Algorithms for Entity Resolution. VLDBJ 32(6): 1369-1400 (2023)
- N. Fanourakis, V. Efthymiou, D. Kotzinos, V. Christophides. Knowledge Graph Embedding Methods for Entity Alignment: An Experimental Review. Data Mining and Knowledge Discovery 37(5): 2070-2137 (2023)
- V. Christophides, V. Efthymiou, T. Palpanas, G. Papadakis, K. Stefanidis. An Overview of End-to-End Entity Resolution for Big Data. ACM Computing Surveys 53(6): 127:1-127:42 (2021)
- A. Vretinaris, C. Lei, V. Efthymiou, X. Qin, F. Özcan. Medical Entity Disambiguation using Graph Neural Networks. SIGMOD 2021
- S. Ahmetaj, V. Efthymiou, R. Fagin, P. Kolaitis, C. Lei, F. Özcan, L. Popa. Ontology-Enriched Query Answering on Relational Databases. IAAI 2021
- J. Hao, C. Lei, V. Efthymiou, A. Quamar, F. Özcan, Y. Sun, W. Wang. MEDTO: Medical Data to Ontology Matching using Hybrid Graph Neural Networks. KDD 2021
- J. Sen, C. Lei, A. Quamar, F. Özcan, V. Efthymiou, A. Dalmia, G. Stager, A. Mittal, D. Saha, K. Sankaranarayanan. ATHENA++: Natural Language Querying for Complex Nested SQL Queries. PVLDB 13(11): 2747-2759 (2020)