On November 20th, 2018, Leif Harald Karlsen defended his dissertation for the degree of Ph.D. The title of the dissertation was “A simple, General and Efficient Representation of Qualitative Spatial Information; An Approach Based on Bintrees”. The adjudication committee consisted of Professor Anthony Cohn (School of Computing, University of Leeds, UK), Professor Hanan Samet (Computer Science Department, University of Maryland, USA) and Professor Vera Hermine Goebel (Department of Informatics, University of Oslo). Leif Harald was supervised by Professor Martin Giese and Professor Arild Waaler. This worked looked at new ways in which computers can represent and search for spatial data in databases. The approach Leif Harald used was to translate complicated spatial objects into simpler structures, bintrees, in a way that the qualitative information in the data is maintained. This allows faster and better access to this data.