Which mathematician contributed most to the decidability of various algebraic groups, Anatoly Maltsev or Semyon Aranovich Gershgorin?
Anatoly Ivanovich Maltsev
Title: Group scheme
Passage: In mathematics, a group scheme is a type of algebro-geometric object equipped with a composition law.  Group schemes arise naturally as symmetries of schemes, and they generalize algebraic groups, in the sense that all algebraic groups have group scheme structure, but group schemes are not necessarily connected, smooth, or defined over a field.  This extra generality allows one to study richer infinitesimal structures, and this can help one to understand and answer questions of arithmetic significance.  The category of group schemes is somewhat better behaved than that of group varieties, since all homomorphisms have kernels, and there is a well-behaved deformation theory.  Group schemes that are not algebraic groups play a significant role in arithmetic geometry and algebraic topology, since they come up in contexts of Galois representations and moduli problems.  The initial development of the theory of group schemes was due to Alexander Grothendieck, Michel Raynaud and Michel Demazure in the early 1960s.
Title: Anatoly Maltsev
Passage: Anatoly Ivanovich Maltsev (also: Malcev, Mal'cev; Russian: Анато́лий Ива́нович Ма́льцев; 27 November N.S./14 November O.S. 1909, Moscow Governorate – 7 June 1967, Novosibirsk) was born in Misheronsky, near Moscow, and died in Novosibirsk, USSR.  He was a mathematician noted for his work on the decidability of various algebraic groups. Malcev algebras (generalisations of Lie algebras) are named after him.
Title: Semyon Aranovich Gershgorin
Passage: Semyon Aronovich Gershgorin (August 24, 1901 – May 30, 1933) was a Soviet (born in Pruzhany, Belarus, Russian Empire) mathematician.  He began as a student at the Petrograd Technological Institute in 1923, became a Professor in 1930, and was given an appointment at the Leningrad Mechanical Engineering Institute in the same year.  His contributions include the Gershgorin circle theorem.
Anatoly Maltsev Semyon Aranovich Gershgorin