For more than 10 years I have been working at the intersection of data, semantics, language and software, contributing in building knowledge-based systems that deliver value to business and society. Born and raised in Athens, Greece, I currently work as Head of Ontology at Textkernel, in Amsterdam, Netherlands, where I lead a team of data professionals (Linguists, Data Scientists and Data Engineers) in developing and delivering a large cross-lingual Knowledge Graph in the HR and Recruitment domain. Prior to Textkernel, I worked at Expert System Iberia (former iSOCO) in Madrid, Spain, as a Research Manager, and at IMC Technologies in Athens, Greece, as a Semantic Solutions Architect and Ontologist.
Academically, I hold a PhD in Knowledge Engineering and Management from National Technical University of Athens, and I have published 60 papers at international conferences, journals and books. I strive though to present my work and experiences in all kinds of venues, trying to bridge the gap between academia and industry so that they can benefit from one another.
Talks, Tutorials and other ActivitiesSee Complete List
Oct 4th 2019, London, United Kingdom
From Taxonomies and Schemas to Knowledge Graphs – Recognizing and tackling the pitfalls of large-scale semantic modeling
This tutorial will take participants into an investigative journey in the semantics of knowledge graphs. teach them how to recognize modeling pitfalls that undermine their quality and value, and provide them with concrete strategies and techniques for avoiding these pitfalls in their own work
Sep 25th 2019, New York, USA
Mind the Semantic Gap: How “talking semantics” can help you perform better data science.
In this talk, I present cases where making fine, seemingly pedantic, distinctions in the meaning of analytics tasks and their related data has helped significantly improve their effectiveness.
Nov 8th 2019, Stuttgart, Germany
How many truths can you handle? Strategies and techniques for handling vagueness in data models
In this talk I will present a set of practical strategies and techniques for tackling vagueness in data modeling and creating models that are semantically more accurate and interoperable.
Nov 7th 2018, London, United Kingdom
Crafting a Knowledge Graph Strategy – What to think about
In this talk, I describe some key strategic dilemmas that Architects and Executives face when designing and executing Knowledge Graph projects, and discuss potential ways to deal with them.
Jun 7th 2018, Heraklion, Greece
Why I don’t care for your F1 score – Evaluating Knowledge Extraction Tools for Industry Use
In this talk I describe five key questions tto use when scrutinizing knowledge extraction tools for industry use, along with the kind of answers you should seek to get.
Jun 3rd 2018, Heraklion, Greece
Executing Knowledge Graph Initiatives in Organizations – A Field Guide
In this tutorial I describe the dimensions and challenges that Knowledge Architects need to be aware of before launching a Knowledge Graph initiative in an organization and provide framework to guide the successful execution of a knowledge graph projects
Mar 22nd 2018, Stockholm, Sweden
Building, Applying and Evolving Knowledge Graphs in Organizations – Dimensions, Methods and Challenges
In this talk, I discuss the technical, business and organizational dimensions and challenges of Knowledge Graph initiatives, and share relevant best practices and lessons learned.
Apr 18th 2018, Corfu, Greece
Ontology modeling in practice – Common pitfalls and how to avoid them
In this lecture I provide an overview of the most common pitfalls in ontology and semantic data modeling and describe good practices that help avoid them.
Feb 23rd 2018, Amsterdam, The Netherlands
Search Engines and Knowledge Graphs: It’s complicated!
In this talk I describe 3 important pitfalls that knowledge-based search engine designers often fall into and suggest ways to avoid them.
Selected PublicationsSee Complete List
R. Denaux , Y. Ren, B. Villazon-Terrazas, P. Alexopoulos, A. Faraotti, H. Wu (2017), “Knowledge Architecture for Organisations” , In Jeff Z. Pan, Guido Vetere, Jose Manuel Gomez-Perez, Honghan Wu (editors), Exploiting Linked Data and Knowledge Graphs in Large Organisations, Springer. 2017.
M. Monti , F. Perego, Y. Zhao, G. Vetere, J.M. Gomez-Perez, P. Alexopoulos, H. Nguyen, G. Webster, B. Villazon-Terrazas, N. Garcia-Santa, J.Z. Pan (2017), “Enterprise Knowledge Graphs: Success Stories” , In Jeff Z. Pan, Guido Vetere, Jose Manuel Gomez-Perez, Honghan Wu (editors), Exploiting Linked Data and Knowledge Graphs in Large Organisations, Springer. 2017.
A. Moschitti , K. Tymoshenko, P. Alexopoulos, A. Walker, M. Nicosia, G. Vetere, A. Faraotti, M. Monti, J.Z. Pan, H. Wu, Y. Zhao (2017), “Question Answering and Knowledge Graphs” , In Jeff Z. Pan, Guido Vetere, Jose Manuel Gomez-Perez, Honghan Wu (editors), Exploiting Linked Data and Knowledge Graphs in Large Organisations, Springer. 2017.
P. Alexopoulos , Y. Zhao, J.Z. Pan, M. Zhu (2017), “Construction of Enterprise Knowledge Graphs (II)” , In Jeff Z. Pan, Guido Vetere, Jose Manuel Gomez-Perez, Honghan Wu (editors), Exploiting Linked Data and Knowledge Graphs in Large Organisations, Springer. 2017.
B. Villazon-Terrazas , N. Garcia-Santa, Y. Ren, K. Srinivas, M. Rodriguez-Muro, P. Alexopoulos, J.Z. Pan (2017), “Construction of Enterprise Knowledge Graphs (I)” , In Jeff Z. Pan, Guido Vetere, Jose Manuel Gomez-Perez, Honghan Wu (editors), Exploiting Linked Data and Knowledge Graphs in Large Organisations, Springer. 2017.
P. Alexopoulos, M.Wallace (2015), “Creating Domain-Specific Semantic Lexicons for Aspect-Based Sentiment Analysis”, 1oth International Workshop on Semantic Media and Adaptation (SMAP), November 5-6, 2015, Trento, Italy..
P. Alexopoulos, R. Denaux, J.M. Gomez-Perez (2015), “Troubleshooting and Optimizing Named Entity Resolution Systems in the Industry”, 12th Extended Semantic Web Conference (ESWC), Portoroz, Slovenia, May 31st – June 4th, 2015.
P. Alexopoulos, S. Peroni, B. Villazon-Terrazas, J.Z. Pan, J.M. Gomez-Perez (2014), “A Metaontology for Annotating Ontology Entities with Vagueness Descriptions”, In Fernando Bobillo‚ Rommel Carvalho‚ Paulo Cesar G. da Costa‚ Claudia d’Amato‚ Nicola Fanizzi‚ Kathryn B. Laskey‚ Kenneth J. Laskey‚ Thomas Lukasiewicz‚ Matthias Nickles and Michael Pool, editors, Uncertainty Reasoning for the Semantic Web III‚ International Workshops URSW 2011−2013‚ Held at ISWC‚ Revised Selected Papers. Springer. 2014. [BibTex, PDF]
P. Alexopoulos, J. Pavlopoulos (2014), “A Vague Sense Classifier for Detecting Vague Definitions in Ontologies”. In Proceedings of the 14th Conference of the European Chapter of the Association for Computational Linguistics (EACL 2014), Gothenburg, Sweden, 2014. [BibTex, PDF]
P. Alexopoulos, C. Ruiz, J.M. Gómez-Pérez (2012), “Scenario-Driven Selection and Exploitation of Semantic Data for Optimal Named Entity Disambiguation”, Proceedings of the 1st Semantic Web and Information Extraction Workshop (SWAIE 2012), Galway, Ireland, October 8-12, 2012. [
P. Alexopoulos, M. Wallace, K. Kafentzis, D. Askounis (2011), “IKARUS-Onto: A Methodology to Develop Fuzzy Ontologies from Crisp Ones” , Knowledge and Information Systems, Volume 32, Issue 3, Page 667-695. [BibTex, PDF]