I work on search engines and the systems behind them: how the Web changes, how to crawl what search engines miss, how to index and query it at scale, and, increasingly, how retrieval and large language models fit together.
I am an Assistant Professor in the Department of Informatics and Telecommunications at the National and Kapodistrian University of Athens. I received my Ph.D. and M.Sc. in Computer Science from UCLA, and my M.Sc. and Engineering Diploma from the Computer Engineering and Informatics Department of the University of Patras.
Before joining the university I spent more than a decade building production systems in industry: at Microsoft Research, where my work shipped in Bing, and at Zynga, Samsung Research and LinkedIn, on web spam detection, commercial and social search, social gaming, IoT and computational advertising. I co-founded the search start-up Infocious (now part of Piksel), and I hold 20 US patents.
My work has received the Best Paper Award at ICDE and a Best Paper runner-up at WWW, and I served as Program Co-Chair of PAKDD 2020.
Research
Retrieval, LLMs and knowledge graphs
Retrieval-augmented generation, LLMs as search engines, and knowledge-graph–based recommendation.
Crawling and the evolving Web
Measuring how the Web changes, detecting change efficiently, and crawling the hidden Web behind search forms.
Search engine systems
Index pruning and tiering, graceful degradation under load, and answering web queries over structured data.
Quality, spam and privacy
Content-based web spam detection, review quality and selection, and releasing search logs privately.
Graphs and streams
Scalable community detection over graph streams and monitoring social activity in real time.
Teaching
K24Systems Programming
Undergraduate. The Linux programming environment: processes, threads, IPC and sockets.
M111Big Data Management
Graduate. Principles and systems of big data management and data science, from MapReduce to streams and graphs.
M151Web Information Systems and Applications
Graduate. Crawling, indexing, neural IR, retrieval-augmented generation and LLM-based search.
Students
I supervise PhD, MSc and BSc theses on search, crawling, data systems and applied LLMs. If you are a DIT student interested in working with me, email me with your transcript and the topics that interest you.