Research

Research Interests
The research interests focus in the general area of Data Management, which includes (among others) the fields of Data Bases, Data Mining, Data Warehouses, Information Systems (e.g. Web Information Systems, Geographic Information Systems), as well as the recently established fields of Big Data (streams), Graph Databases, Sensor/Social Networks, and so on. Also, of interest are the areas of Web Information Retrieval and Mining, Blog Preservation and Informetrics (Scientometrics, Webometrics and Bibliometrics). In the past, contributed in the interface area between Data Bases and Operating Systems.

Invited talks
He delivered keynote talks at the following conferences:  ESSE'2023@Naploli, IC3K-WEBIST'2023@Rome, COPA'2023@Limassol, MICA'2022@Tamil Nadu, ICCCI'2021@Rhodes, DMCESE'2021@PanamaCity,  CPS&IoT'2021@Budva, AIMinScience'2020@Lyon, SADASC'2020@Marrakesh, SEIM'2020@St.Petersburg, ICBICC'2019@Rome, INISTA'2019@Sofia, PCI'2018@Athens, IDEAS'2018@Calabria, SOFSEM'2018@Krems, ICCCI'2017@Nicosia, ICAR'2015@Beirut, IISA'2015@Corfu, ScienceWeek'2015@Kosovo, ISPS'2015@Algiers, RTA-CSIT'2014@Tirana, SMAP'2014@Corfu, ODBD'2014@Beirut, MEDES'2013@Luxemburg, ICEIS'2012@Wroclaw, CEE'211@Cluj-Napoca, CompSysTech'2010@Sofia, SOFSEM'2010@SpindleruvMlyn, SYRCODIS'2008@St.Petersburg.

Funding
Participated in a number of R&D projects funded by EU and national state/private funds as project leader or researcher. As project leader he attracted funding of 2,2 Meuros. 

Advising
Participated/participates as external expert and advisor in EU projects (AI4Media, Mind4Machines, Terminet, Exa4Mind).

Impact
• Received >18.000 citations according Google Scholar from >2800 distinct academic institutions frοm >100 countries 
• H-index=61 and ranked 1st Computer Science author of Cypriot universities according to Research.com
• Listed in the top-10 most cited authors of Aristotle University of Thessaloniki according to Google Scholar (until September 2020).
• Listed in the top-10 computer science authors of Greek universities with highest h-index value according to Guide2Research (until September 2020).

• Listed in the top-1000 most prolific authors according to DBLP digital library (Data Bases and Logic Programming).

• Listed among the top-714 Greek scientists with the greatest impact according to a study of Prof Yannis Ioannidis, Meta-Research Innovation Center at Stanford (METRICS).
• Included in the list of top-2% of the most cited scientists world-wide according to "October 2023 data-update for "Updated science-wide author databases of standardized citation indicators" by Ioannidis J., Stanford University. 

Best Paper Awards
• "Fast Subsequence Matching in Time-Series Databases", ACM SIGMOD Conference, Minneapolis, MN, 1994.
• "SkyGraph: An Algorithm for Important Subgraph Discovery in Relational Graphs", ECML/PKDD Conference, Antwerp, Belgium, 2008.
• "A Bi-objective Cost Model for Database Queries in a Multi-cloud Environment", ACM MEDES Conference, Buraydah, Saudi Arabia, 2014.
• "Early Malicious Activity Discovery in Microblogs by Social Bridges Detection", IEEE ISSPIT Workshop, Limassol, Cyprus, 2016.
• "Detecting Intrinsic Dissimilarities in Large Image Databases through Skylines", ACM MEDES Conference, Bangkok, Thailand, 2017.