Which mathematician contributed most to the decidability of various algebraic groups, Anatoly Maltsev or Semyon Aranovich Gershgorin?
Anatoly Maltsev:  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. Semyon Aranovich Gershgorin:  His contributions include the Gershgorin circle theorem.
i don't know