Truszczynski's research interests include knowledge representation, nonmonotonic reasoning, logic programming, and constraint satisfaction and programming. He is the author or co-author of over 180 technical papers in journals, conference proceedings and books. Jointly with Victor Marek he wrote a research monograph "Nonmonotonic Logic" on mathematical foundations of nonmonotonic reasoning, which marked a milestone in the development of the field.
His paper Stable Logic Programming, also a joint work with Victor Marek, helped launch the field of answer-set programming. Truszczynski was also a co-editor of ten conference proceedsings and article collections, including "The Logic Programming Paradigm: a 25-Year Perspective", celebrating accomplishments of the field of logic programming, "Nonmonotonic Reasoning at 30," assessing advances in nonmonotonic reasoning 30 years after the field had been established, Proceedings of International Conference on Logic Programming, ICLP 2006, and Proceedings of the International Conference on Knowledge Representation and Reasoning, KR 2010.
Truszczynski is active in his research community. He was an organizer and the program committee chair for several major conferences in his field. He served on the Executive Committee of the Association of Logic Programming (2003-2008), and as Chair of the Steering Committee of Nonmonotonic Reasoning Workshops (2000 - 2008). He was a member of the Steering Committee of Knowledge Representation, Inc. (2000 - 2014) and in 2010-2012 he served as President of that organization. Truszczynski served on editorial and advisory boards of several professional journals, including Journal of Artificial Intelligence Research, Artificial Intelligence Journal, and Theory and Practice of Logic Programming. He currently is the Editor-in-Chief of Theory and Practivce of Logic Programming and an associate editor for AI Communications.
In 2013, Truszczynski was elected Fellow of the Association for the Advancement of Artificial Intelligence (AAAI). In 2021, he was elected Fellow of the Asia-Pacific Artificial Intelligence Association (AAIA), and in 2023 he received the Dov Gabbay Prize.
In 2023, Truszczynski retired from the University of Kentucky.