16D60 16D70 3 13A15 1 13C05 1 13C13 1 13H15 1 16D10 1 16D25 1 16D90 1 16D99 1 16P40 1 16P50 1 17B10 1 17B35 1 17B37 1 17B67 1 81R10 1 Cantor-Bernstein Theorem 1 Gelfand-Tsetlin basis 1 Gelfand-Tsetlin modules 1 \(S\)-cotorsion-free module 1 \(S\)-second submodule 1 \(\oplus_{ss}\)-supplemented module 1 \(ss\)-supplement submodule 1 correct classes 1 homological classification of rings 1 maximal ideal 1 prime ideal 1 prime spectrum 1 second submodule 1