Skip to main content Skip to local navigation

Walter Tholen

Walter Tholen

Picture of Walter Tholen
Walter Tholen
Professor Emeritus


Mathematics and Statistics


Google Scholar


Office Location Ross Building, N605
Phone Number (416)736-2100 x 33918 (Voicemail)


Walter Tholen received his Ph.D. (Dr. rer. nat.) from the University of Münster in 1974 and his Habilitation four years later from Fernuniversität Hagen, Germany. Since 1983 he has been working at York University in Toronto, assuming the position of Full Professor in 1988. He chaired the Department of Mathematics and Statistics from 1989 until 1992. In 2007 he was appointed Associate Dean (Research and Faculty Affairs) in the Faculty of Science and Engineering, and in 2009-10 he served the Faculty as Interim Dean. From 2011 to 2015 he served the University as Associate Vice-President Research. He was Visiting Professor at numerous institutions, including ETH Zürich, Max Plack Institute for Mathematics in Bonn, University of British Columbia, McGill University, University of Sydney, Hungarian Academy of Sciences, Georgian Academy of Sciences, University of Coimbra, University of L'Aquila, University of Trieste, University of Perugia, Masaryk University, Université Catholique de Louvain, Université du Littoral, University of Bremen, and Fernuniversität. His general research interests are in Category Theory and its applications to Algebra, Topology, and Computer Science. Much of his work concerns the establishment of algebraic and topological facts in arbitrary categories, without recourse to sets. He co-authored a monograph on The Categorical Structure of Closure Operators with D. Dikranjan (Kluwer-Springer, 1995) and co-edited books on Categorical Foundations (with M. C. Pedicchio, Cambridge University Press, 2004), Galois Theory, Hopf Algebras, and Semiabelian Categories (with George Janelidze and Bodo Pareigis, American Mathematical Society, 2004), and most recently on Monoidal Topology (with Dirk Hofmann and Gavin J. Seal, Cambridge University Press, 2014). He has published some 120 research articles in scientific journals, and his work is supported by the Natural Sciences and Engineering Council of Canada. He is a member of the editorial boards of Applied Categorical Structures (ACS, Springer), Theory and Applications of Categories (TAC, electronic journal) and of the Journal of Homotopy Theory and Related Structures (electronic journal), and he co-edited a number of conference proceedings and special volumes that appeared in ACS, TAC, Topology Applications (Elsevier), and Lecture Notes in Mathematics (Springer)."


Specializing in category theory and its applications to algebra, topology and computer science.

Research Areas

Pure Mathematics