| 16-XX | Associative rings and algebras 
{For the commutative case, see 
13-XX} | 
| 16-00 | General reference works (handbooks, dictionaries, bibliographies, etc.) | 
| 16-01 | Instructional exposition (textbooks, tutorial papers, etc.) | 
| 16-02 | Research exposition (monographs, survey articles) | 
| 16-03 | Historical {!must also be assigned at least one classification number from section 01} | 
| 16-04 | Explicit machine computation and programs (not the theory of computation or programming) | 
| 16-06 | Proceedings, conferences, collections, etc. | 
| 16Bxx | General and miscellaneous | 
| 16B50 | Category-theoretic methods and results {!except as in 
16D90,
 
16E10}
 
[See also 
18-XX] | 
| 16B70 | Applications of logic 
[See also 
03Cxx] | 
| 16B99 | None of the above, but in this section | 
| 16Dxx | Modules, bimodules and ideals | 
| 16D10 | General module theory | 
| 16D20 | Bimodules | 
| 16D25 | Ideals | 
| 16D30 | Infinite-dimensional simple rings (except as in 
16Kxx) | 
| 16D40 | Free, projective, and flat modules and ideals 
[See also 
19A13] | 
| 16D50 | Injective modules, self-injective rings 
[See also 
16L60] | 
| 16D60 | Simple and semisimple modules, primitive rings and ideals | 
| 16D70 | Structure and classification {!except as in 
16Gxx},
 direct sum decomposition, cancellation | 
| 16D80 | Other classes of modules and ideals 
[See also 
16G60] | 
| 16D90 | Module categories 
[See also 
16Gxx,
 
16S90];
 module theory in a category-theoretic context; Morita equivalence and duality | 
| 16D99 | None of the above, but in this section | 
| 16Exx | Homological methods 
{For commutative rings, see 
13Dxx;
 for general categories, see 
18Gxx} | 
| 16E05 | Syzygies, resolutions, complexes | 
| 16E10 | Homological dimension | 
| 16E20 | Grothendieck groups, K-theory, etc. 
[See also 
18F30,
 
19Axx,
 
19D50] | 
| 16E30 | Homological functors on modules (Tor, Ext, etc.) | 
| 16E40 | (Co)homology of rings and algebras (e.g. Hochschild, cyclic, dihedral, etc.) | 
| 16E45 | Differential graded algebras and applications | 
| 16E50 | Von_Neumann regular rings and generalizations | 
| 16E60 | Semihereditary and hereditary rings, free ideal rings, Sylvester rings, etc. | 
| 16E65 | Homological conditions on rings (generalizations of regular, Gorenstein, Cohen - Macaulay rings, etc.) | 
| 16E99 | None of the above, but in this section | 
| 16Gxx | Representation theory of rings and algebras | 
| 16G10 | Representations of Artinian rings | 
| 16G20 | Representations of quivers and partially ordered sets | 
| 16G30 | Representations of orders, lattices, algebras over commutative rings 
[See also 
16H05] | 
| 16G50 | Cohen - Macaulay modules | 
| 16G60 | Representation type (finite, tame, wild, etc.) | 
| 16G70 | Auslander - Reiten sequences (almost split sequences) and Auslander - Reiten quivers | 
| 16G99 | None of the above, but in this section | 
| 16H05 | Orders and arithmetic, separable algebras, Azumaya algebras 
[See also 
11R52,
 
11R54,
 
11S45] | 
| 16Kxx | Division rings and semisimple Artin rings 
[See also 
12E15,
 
15A30] | 
| 16K20 | Finite-dimensional 
{For crossed products, see 
16S35} | 
| 16K40 | Infinite-dimensional and general | 
| 16K50 | Brauer groups 
[See also 
12G05,
 
14F22] | 
| 16K99 | None of the above, but in this section | 
| 16Lxx | Local rings and generalizations | 
| 16L30 | Noncommutative local and semilocal rings, perfect rings | 
| 16L60 | Quasi-Frobenius rings 
[See also 
16D50] | 
| 16L99 | None of the above, but in this section | 
| 16Nxx | Radicals and radical properties of rings | 
| 16N20 | Jacobson radical, quasimultiplication | 
| 16N40 | Nil and nilpotent radicals, sets, ideals, rings | 
| 16N60 | Prime and semiprime rings 
[See also 
16D60,
 
16U10] | 
| 16N80 | General radicals and rings 
{For radicals in module categories, see 
16S90} | 
| 16N99 | None of the above, but in this section | 
| 16Pxx | Chain conditions, growth conditions, and other forms of finiteness | 
| 16P10 | Finite rings and finite-dimensional algebras 
{For semisimple, see 
16K20;
 for commutative, see 
11Txx,
 
13Mxx} | 
| 16P20 | Artinian rings and modules | 
| 16P40 | Noetherian rings and modules | 
| 16P50 | Localization and Noetherian rings 
[See also 
16U20] | 
| 16P60 | Chain conditions on annihilators and summands: Goldie type conditions 
[See also 
16U20],
 Krull dimension | 
| 16P70 | Chain conditions on other classes of submodules, ideals, subrings, etc.; coherence | 
| 16P90 | Growth rate, Gelfand - Kirillov dimension | 
| 16P99 | None of the above, but in this section | 
| 16Rxx | Rings with polynomial identity | 
| 16R10 | T-ideals, identities, varieties of rings and algebras | 
| 16R20 | Semiprime p.i. 
Rings, rings embeddable in matrices over commutative rings | 
| 16R30 | Trace rings and invariant theory | 
| 16R40 | Identities other than those of matrices over commutative rings | 
| 16R50 | Other kinds of identities (generalized polynomial, rational, involution) | 
| 16R99 | None of the above, but in this section | 
| 16Sxx | Rings and algebras arising under various constructions | 
| 16S10 | Rings determined by universal properties (free algebras, coproducts, adjunction of inverses, etc.) | 
| 16S15 | Finite generation, finite presentability, normal forms (diamond lemma, term-rewriting) | 
| 16S20 | Centralizing and normalizing extensions | 
| 16S30 | Universal enveloping algebras of Lie algebras 
[See mainly 
17B35] | 
| 16S32 | Rings of differential operators 
[See also 
13N10,
 
32C38] | 
| 16S34 | Group rings 
[See also 
20C05,
 
20C07],
 Laurent polynomial rings | 
| 16S35 | Twisted and skew group rings, crossed products | 
| 16S36 | Ordinary and skew polynomial rings and semigroup rings 
[See also 
20M25] | 
| 16S37 | Quadratic and Koszul algebras | 
| 16S38 | Rings arising from non-commutative algebraic geometry | 
| 16S40 | Smash products of general Hopf actions 
[See also 
16W30] | 
| 16S50 | Endomorphism rings; matrix rings 
[See also 
15-XX] | 
| 16S60 | Rings of functions, subdirect products, sheaves of rings | 
| 16S70 | Extensions of rings by ideals | 
| 16S80 | Deformations of rings 
[See also 
13D10,
 
14D15] | 
| 16S90 | Maximal ring of quotients, torsion theories, radicals on module categories 
[See also 
13D30,
 
18E40]
 
{For radicals of rings, see 
16Nxx} | 
| 16S99 | None of the above, but in this section | 
| 16Uxx | Conditions on elements | 
| 16U10 | Integral domains | 
| 16U20 | \Ore rings, multiplicative sets, \Ore localization | 
| 16U30 | Divisibility, noncommutative UFDs | 
| 16U60 | Units, groups of units | 
| 16U70 | Center, normalizer (invariant elements) | 
| 16U80 | Generalizations of commutativity | 
| 16U99 | None of the above, but in this section | 
| 16Wxx | Rings and algebras with additional structure | 
| 16W10 | Rings with involution: Lie, Jordan and other nonassociative structures 
[See also 
17B60,
 
17C50,
 
46Kxx] | 
| 16W20 | Automorphisms and endomorphisms | 
| 16W22 | Actions of groups and semigroups; invariant theory | 
| 16W25 | Derivations, actions of Lie algebras | 
| 16W30 | Coalgebras, bialgebras, Hopf algebras 
[See also 
57T05,
 
16S30,
 
16S40];
 rings, modules, etc. 
On which these act | 
| 16W35 | Ring-theoretic aspects of quantum groups 
[See also 
17B37,
 
20G42,
 
81R50] | 
| 16W50 | Graded rings and modules | 
| 16W55 | ``Super'' (or ``skew'') structure 
[See also 
17A70,
 
17C70]
 
{For exterior algebras, see 
15A75;
 for Clifford algebras, see 
11E88,
 
15A66} | 
| 16W60 | Valuations, completions, formal power series and related constructions 
[See also 
13Jxx] | 
| 16W70 | Filtered rings; filtrational and graded techniques | 
| 16W80 | Topological and ordered rings and modules 
[See also 
13Jxx] | 
| 16W99 | None of the above, but in this section | 
| 16Yxx | Generalizations 
{For nonassociative rings, see 
17-XX} | 
| 16Y30 | Near-rings 
[See also 
12K05] | 
| 16Y60 | Semirings 
[See also 
12K10] | 
| 16Y99 | None of the above, but in this section | 
| 16Z05 | Computational aspects of associative rings 
[See also 
68W30] |