Original: Christian Felix Klein (25 April 1849 â "22 June 1925) was a German mathematician, known for his work in group theory, function theory, non-Euclidean geometry, and on the connections between geometry and group theory.
Simplified: Felix Christian Klein (April 25, 1849, DÃ 1\/4 sseldorf, (then) Prussian Empire - June 22, 1925, GÃ ttingen, Germany) was a German mathematician. He became known for his work in group theory, function theory, non-Euclidean geometry, and on the connections between geometry and group theory.