Emanuels Grīnbergs

Emanuels Donats Frīdrihs Jānis Grinbergs (1911–1982, westernized as Emanuel Grinberg) was a Latvian mathematician, known for Grinberg's theorem on the Hamiltonicity of planar graphs.

Biography Grinbergs was born on January 25, 1911, in St. Petersburg, the son of a Lutheran bishop from Latvia. Latvia became independent from Russia in 1917, and on the death of his father in 1923, Grinbergs' family returned to Riga, taking Grinbergs with them.

In the meantime, the Soviet Union had annexed Latvia in 1940, and the army of Nazi Germany had occupied it and incorporated it into the Reichskommissariat Ostland. Grinbergs was drafted into the Latvian Legion, part of the German military, in 1944. After the war, because of his service as a German soldier, he was held prisoner in a camp in Kutaisi, Georgia, until 1946; he lost his university position, and his doctorate (awarded during the German occupation) was annulled.

In 1954, Grinbergs was allowed to return to the University of Latvia faculty. In 1956, he joined the Institute of Physics of the Latvian Academy of Sciences, and in 1960, he began working at the Computer Center of the University of Latvia, where he remained for the rest of his career, eventually becoming Chief Scientist there. His researches in graph theory also concerned graph coloring, graph isomorphism, cycles in directed graphs, and a counterexample to a conjecture of András Ádám on the number of cycles in tournaments.

Other topics in Grinbergs' research include Steiner triple systems, magnetohydrodynamics, operations research, and the mathematical modeling of hydrocarbon exploration.