Ola Bratteli (24 October 1946 – 8 February 2015) was a Norwegian mathematician.
He was a son of Trygve Bratteli and Randi Bratteli (née Larssen). He received a PhD degree in 1974. He was appointed as professor at the University of Trondheim in 1980 and at the University of Oslo in 1991. He was a member of the Norwegian Academy of Science and Letters.
Joseph Marie de Tilly (16 August 1837 – 4 August 1906) was a Belgian military man and mathematician.
He was born in Ypres, Belgium. In 1858, he became a teacher in mathematics at the regimental school. He began with studying geometry, particularly Euclid's fifth postulate and non-Euclidean geometry. He found similar results as Lobachevsky in 1860, but the Russian mathematician was already dead at that time. Tilly is more known for his work on non-Euclidean mechanics, as he was the one who invented it. He worked thus alone on this topic until a French mathematician, Jules Hoüel, showed interest in that field. Tilly also wrote on military science and history of mathematics. He died in München, Germany.
Constantin Marie Le Paige (9 March 1852 – 26 January 1929) was a Belgian mathematician.
Born in Liège, Belgium, Le Paige began studying mathematics in 1869 at the University of Liège. After studying analysis under Professor Eugène Charles Catalan, Le Paige became a professor at the Université de Liège in 1882.
While interested in astronomy and the history of mathematics, Le Paige mainly worked on the theory of algebraic form, especially algebraic curves and surfaces and more particularly for his work on the construction of cubic surfaces. Le Paige remained at the university until his retirement in 1922.
Nicolaas George Wijnand Henri Beeger (1884, in Utrecht – 1965, in Amsterdam) was a Dutch mathematician. His 1916 doctorate was on Dirichlet series. He worked for most of his life as a teacher, working on mathematics papers in his spare evenings. After his retirement as a teacher at 65, he began corresponding with many contemporary mathematicians and dedicated himself to his work. Tilburg University still holds biennial lectures entitled the Beeger lectures in his honour.
He is known for having proved that 3511 is a Wieferich prime in 1922 and for introducing the term Carmichael number in 1950.