Infinite solvable and finitely approximable groups

Author's abstract of a dissertation presented as a requirement for the academic degree of Doctor of Physical and Mathematical Sciences. The dissertation was defended on June 21, 1974 at a meeting of the Academic Council of the Institute of Mathematics, Siberian Branch, Academy of Sciences of the USSR. Official opponents: Professor Yu. L. Ershov, Professor S. I. Adyan, and Professor A. I. Starostin.