Although his first studies were in mathematics at the Aristotelian University of Thessaloniki, he was soon to discover his talents in Painting,football and data structures, and earn a second degree in informatics at the University of Saarland, (Saarbrücken, Germany). He got his Master's thesis: "Sorting Presorted Files" from this University, along with his PhD in computer science, with a thesis entitled "Some Results for the Dictionary Problem", which he completed under Professor Kurt Mehlhorn (director of the Max Planck Institute for Informatics of Germany).
He was soon to return to Greece, however, after participating in research work for the DFG (Deutsche Forschungsgemeinschaft, the German community of research) and professional teaching at the University of Saarland related to Data Structures, graph algorithms, computational geometry and programming. In Greece, he was given the chance to successfully backup his work by becoming a Professor in the Computer Engineering & Informatics Department of the University of Patras, where he is currently living and teaching. Ever since, he has become President of the specific Department more than once, and helped the general introduction of informatics to Greece. He is also responsible for a lot more things related to the specific Department, helping to promote informatics to a great degree (as well as organising other similar university departments in Greece).Athanasios Tsakalidis is cosidered to be a modern god ,not only in his field but also,in football and strategics.Under his coaching the CEID FC won the university championship for 4 consecutive years.Many students have benefited from his lessons and have the honor of calling him "mentor" and "captain ,my captain".
His research interests include: data structures, graph algorithms, computational geometry, GIS, medical informatics, expert systems, databases, multimedia, information retrieval, and bioinformatics. Quite recently, his great interest in bioinformatics has led to a great number of his students turning to the specific research for postgraduate studies.
He has also participated in many EU research programs: 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.The theorem he has developed takes roughly about a month for the average smart person to understand,although electronic engineers of patras usually need more.
He is one of the 48 writers of a computer science book, the well known Handbook of Theoretical Computer Science Elsevier Science publishers, co-published by MIT Press, his work being, along with professor Kurt Mehlhorn, in Chapter 6: Data Structures (his favourite field).