During his PhD studies, David explores a fundamental question in mathematics: how to determine when two structures are truly distinct. A common approach is to study the symmetries of these structures and assign algebraic invariants, which provide crucial information and help distinguish them. David studied the shape and structure of the mathematical worlds where these symmetries and invariants are systematically encoded.

His research explores the role of Nakayama functors within subcategories, rank functions in higher-dimensional settings, and differential modules as a means of approaching questions in representation theory, homological algebra and commutative algebra. The results offer conceptual insights, new frameworks, and modern perspectives on long-standing problems in abstract algebra.

The PhD degree was completed at the Department of Mathematics, Faculty of Natural Sciences, Aarhus University.

This summary was prepared by the PhD student.

Time: Friday, 07-11-2025 at 15:00
Place: Building 1531, room 215, Lecture Theatre Aud. D3, Mathematics, Aarhus University, Ny Munkegade 118, 8000 Aarhus C
Title of PhD thesis: Homological algebra in subcategories: Nakayama functors, rank functions and differential modules
Contact information: David Nkansah, e-mail: David.nkansah@math.au.dk
Members of the assessment committee:
Maitre de Conférence Claire Amiot, Institut Fourier, Université Grenoble Alpes, Frankrig
Senior Lecturer David Pauksztello School of Mathematical Sciences, Lancaster University, Storbritannien
Professor Cristiano Spotti (chair), Mathematics, Aarhus University, Denmark
Main supervisor: Professor Peter Jørgensen, Mathematics, Aarhus University, Denmark
Language: The PhD dissertation will be defended in English

The defence is public.
The PhD thesis is available for reading at the Graduate School of Natural Sciences/GSNS, Ny Munkegade 120, building 1521, 8000 Aarhus C