János Bolyai (; 15 December 1802 – 27 January 1860) or
Johann Bolyai, was a
Hungarian mathematician, one of the founders of
non-Euclidean geometry — a geometry that differs from
Euclidean geometry in its definition of parallel lines. The discovery of a consistent alternative geometry that might correspond to the structure of the universe helped to free mathematicians to study abstract concepts irrespective of any possible connection with the physical world.