Bent Fuglede

Bent Fuglede (1925 to 2023) was a Danish mathematician trained at the University of Copenhagen who worked in functional analysis and potential theory. The Mathematics Genealogy Project records his scient degree there in 1948, with a dissertation on extremal length and closed extensions of partial differential operators written under Børge Jessen, and a further Dr. phil. degree in 1960. It lists his students at Copenhagen, among them Christian Berg, Jens Peter Christensen, Troels Jørgensen and Esben Kehlet. In 1974 he proposed the Fuglede conjecture, which says that a domain of positive finite measure in Euclidean space is a spectral set exactly when it tiles space by translation. The conjecture has since been settled in the negative in some dimensions and remains open in others.