Ivan Petrovsky, Russian mathematician and academic (d. 1973)
Ivan Georgievich Petrovsky (Russian: Ива́н Гео́ргиевич Петро́вский) (18 January 1901 – 15 January 1973) (the family name is also transliterated as Petrovskii or Petrowsky) was a Soviet mathematician working mainly in the field of partial differential equations. He greatly contributed to the solution of Hilbert's 19th and 16th problems, and discovered what are now called Petrovsky lacunas. He also worked on the theories of boundary value problems, probability, and on the topology of algebraic curves and surfaces.