Prof. Athanasios K. Tsakalidis (; born 1950) is a Greek computer scientist, a professor at the Graphics, Multimedia and GIS Laboratory, Computer Engineering and Informatics Department (CEID), University of Patras, Greece. His scientific contributions extend diverse fields of computer science, including data structures, computational geometry, graph algorithms, GIS, bioinformatics, medical informatics, expert systems, databases, multimedia, information retrieval and more. Especially significant contributions include co-authoring Chapter 6: "Data Structures" in the Handbook of Theoretical Computer Science with his advisor prof. Kurt Mehlhorn, as well as numerous other elementary theoretical results that are cataloged in the article Some Results for Elementary Operations published in Efficient Algorithms in celebration of prof. K. Mehlhorn's 60th birthday. Scientific Research His research interests include: Data Structures, Graph Algorithms, Computational Geometry, GIS, Medical Informatics, Expert Systems, Databases, Multimedia, Information Retrieval, and Bioinformatics. He has participated in many EU research programs, such as ESPRIT, RACE, AIM, STRIDE, Basic Research Actions in ESPRIT, ESPRIT Special Actions, TELEMATICS Applications, ADAPT, HORIZON, ΕΠΕΤ ΙΙ, ΥΠΕΡ, ΤΕΝ – TELECOM, IST, LEONARDO DA VINCI, MARIE CURIE, SOCRATES. He is one of the 48 writers (6 of whom have received the ACM Turing Award) of the ground-laying computer science book, Handbook of Theoretical Computer Science, Vol A Elsevier Science publishers, co-published by MIT Press, his work being, along with professor Kurt Mehlhorn, in Chapter 6: Data Structures (his favourite field). His pioneering results on the list manipulation and localized search problems in the 1980s led to the foundation of the ubiquitous persistence theory on data structures, developed by prof. Robert E. Tarjan. Other significant results on the design and analysis of data structures were contributed on the problems of interpolation search, negative cycle and nearest common ancestor, the latter being referenced as "Tsakalidis' Algorithm" in the optimal results of prof. Mikkel Thorup. His extensive work on algorithms, data structures, computational geometry and graph algorithms has been cited and acknowledged by prominent computer scientists like Robert E. Tarjan, Ian J. Munro, Dan Willard, Jon Bentley, Jan van Leeuwen, Timothy M. Chan, Lars Arge, Mihai Patrascu, Erik Demaine, Mikkel Thorup, Prosenjit Bose, Gerth S. Brodal, Haim Kaplan, Peter Widmayer, Giuseppe F. Italiano, Peyman Afshani, Kasper Larsen and more. Academic career Athanasios Tsakalidis obtained his Ph.D. degree in informatics in 1983 at the Computer Science department of Saarland University, Germany. His thesis is entitled "Some Results for the Dictionary Problem" and was completed under the supervision Professor