16S90 3 18E40 3 06A15 1 12H99 1 13D30 1 16D90 1 16N80 1 18A40 1 Bland torsion theory 1 adjoint functors 1 category of modules 1 closure operator 1 differential Bland filter 1 differential homomorphism 1 differential module 1 differential radical filter 1 differential ring 1 differential torsion theory 1 duality 1 lattice of submodules 1 natural transformation 1 preradical 1 radical class 1 semi-simple class 1