Associative rings and algebras
449 ideas in this subject. The map below lists the main ideas of the subject by area, in teaching order. 244 of its 245 ideas have a page so far.
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- ConceptRing
A ring is a set with an addition and a multiplication that obey the usual rules of arithmetic. The multiplication need not be commutative. The integers, the polynomials and the square matrices are the basic examples. The definition of a ring gives the axioms.
- ConceptNoncommutative ring
A noncommutative ring is a ring in which the order of the factors in a product can matter. Matrix rings, quaternions, endomorphism rings and group rings of nonabelian groups are the main sources of examples. Many tools of commutative algebra split into left and right versions in this setting. The study of these rings is the subject of noncommutative ring theory.
- ConceptAssociative algebra
An associative algebra over a commutative ring is a ring whose elements can also be multiplied by scalars from . The scalar product is compatible with the ring product. Matrix algebras, polynomial algebras, group algebras and endomorphism algebras of vector spaces are the standard examples. The notion puts ring theory and linear algebra in one frame, so that dimension and bases are available when is a field. A commutative algebra over a ring is the special case where the ring product is commutative.
- ConceptSubring
A subring is a subset of a ring that contains and and is closed under the ring operations. It is a ring with the operations of the larger ring. The definition of a subring gives the conditions.
- ConceptOpposite ring
The opposite ring of a ring has the same elements and the same addition as , with the factors of every product swapped. A ring equals its opposite exactly when it is commutative. The opposite ring turns right modules into left modules and back. So results proved for one side carry over to the other. It also appears in the endomorphism ring of a ring viewed as a module over itself.
- ConceptRing homomorphism
A ring homomorphism is a map between two rings that preserves addition, multiplication and the identity element. The definition of a ring homomorphism gives the conditions.
Map of the subject
Basic notions 24 of 25
- Ring definition
- Noncommutative ring concept
- Associative algebra definition
- Subring definition
- Opposite ring definition
- Ring homomorphism definition
- Left ideal definition
- Two-sided ideal definition
- Quotient ring definition
- Center of a ring definition
- Centraliser definition
- Unit of a ring definition
- Zero divisor definition
- Domain definition
- Division ring definition
- Idempotent element definition
- Complete set of orthogonal idempotents definition
- Peirce decomposition statement
- Nilpotent element definition
- Nil ideal definition
- Nilpotent ideal definition
- matrix ring definition
- Endomorphism ring definition
- Characteristic of a ring definition
- Rng definition
Modules and ideals 23 of 23
- Module over a ring definition
- Bimodule definition
- Simple module definition
- Schur's lemma statement
- Endomorphism ring of a simple module is a division ring statement
- Semisimple module definition
- Characterizations of semisimple modules statement
- Indecomposable module definition
- Krull–Schmidt theorem statement
- Composition series definition
- Jordan–Hölder theorem statement
- Length of a module definition
- Fitting's lemma statement
- Faithful module definition
- Uniform module definition
- Essential submodule definition
- Socle of a module definition
- Radical of a module definition
- Free module definition
- Invariant basis number definition
- Stably finite ring definition
- Dedekind-finite ring definition
- Eilenberg swindle concept
Semisimple rings and Wedderburn theory 8 of 8
- Simple ring definition
- Matrix rings over simple rings are simple statement
- Semisimple ring definition
- Artin–Wedderburn theorem statement
- Wedderburn's theorem on simple Artinian rings statement
- Wedderburn's little theorem statement
- Maschke's theorem statement
- Separable algebra definition
Division rings and central simple algebras 19 of 19
- The quaternions object
- Quaternion algebra definition
- Frobenius theorem on real division algebras statement
- Central simple algebra definition
- Skolem–Noether theorem statement
- Double centralizer theorem statement
- Splitting field of a central simple algebra definition
- Maximal subfield definition
- Degree of a central simple algebra definition
- Brauer group definition
- Period and index concept
- Crossed product algebra definition
- Cyclic algebra definition
- Albert–Brauer–Hasse–Noether theorem statement
- Amitsur's noncrossed product counterexample
- Cartan–Brauer–Hua theorem statement
- Hua's identity statement
- Azumaya algebra definition
- Clifford algebra definition
Radicals 10 of 10
- Jacobson radical definition
- Jacobson radical of an Artinian ring is nilpotent statement
- Nakayama's lemma statement
- Prime radical definition
- Upper nilradical definition
- Levitzki radical definition
- Brown–McCoy radical definition
- Kurosh–Amitsur radical theory concept
- Köthe conjecture conjecture
- Amitsur's theorem on the radical of polynomial rings statement
Primitive and prime rings 9 of 9
- Primitive ring definition
- Primitive ideal definition
- Jacobson density theorem statement
- Prime ring definition
- Prime ideal in a noncommutative ring definition
- Semiprime ring definition
- Semiprimitive ring definition
- Reduced ring definition
- Kaplansky's theorem on projective modules statement
Local rings and generalizations 9 of 9
- Local ring definition
- Semilocal ring definition
- Semiperfect ring definition
- Perfect ring definition
- Semiprimary ring definition
- Bass's theorem P statement
- Lifting idempotents concept
- Uniserial module definition
- Serial ring definition
Chain, growth and finiteness conditions 19 of 19
- Noetherian ring definition
- Artinian ring definition
- Noetherian module definition
- Artinian module definition
- Hopkins–Levitzki theorem statement
- Artinian reduced rings are semisimple statement
- Ore condition definition
- Ore localization definition
- Goldie's theorem statement
- Goldie ring definition
- Classical ring of quotients definition
- Gelfand–Kirillov dimension definition
- Growth of algebras concept
- Bergman's gap theorem statement
- Kurosh problem problem
- Golod–Shafarevich theorem statement
- Levitzki's theorem statement
- Krull dimension of a noncommutative ring definition
- Lenagan's theorem statement
Polynomial identity rings 6 of 6
- Polynomial identity ring definition
- Amitsur–Levitzki theorem statement
- Kaplansky's theorem on PI rings statement
- Posner's theorem statement
- Central polynomial definition
- Generic matrix algebra definition
Constructions 25 of 25
- Polynomial ring definition
- Free algebra definition
- Tensor algebra definition
- Exterior algebra definition
- Tensor product of algebras definition
- Group ring definition
- Monoid ring definition
- Kaplansky's conjectures conjecture
- Kaplansky's zero divisor conjecture conjecture
- Skew polynomial ring definition
- Ore extension definition
- Weyl algebra definition
- Dixmier conjecture conjecture
- Ring of differential operators definition
- Formal power series definition
- Laurent polynomial ring definition
- Skew group ring definition
- Smash product definition
- Path algebra definition
- Incidence algebra definition
- Universal enveloping algebra definition
- Poincaré–Birkhoff–Witt theorem statement
- Leavitt path algebra definition
- Cohn localization concept
- Direct limit of rings definition
Morita theory 5 of 5
- Morita equivalence definition
- Morita equivalence of a ring with its matrix rings statement
- Progenerator definition
- Morita duality concept
- Morita invariant concept
Homological methods 25 of 25
- Projective module definition
- Injective module definition
- Baer's criterion statement
- Flat module definition
- Injective hull definition
- Projective cover definition
- Ext functor definition
- Tor functor definition
- Global dimension definition
- Weak dimension definition
- Hereditary ring definition
- Semihereditary ring definition
- Frobenius algebra definition
- Quasi-Frobenius ring definition
- Self-injective ring definition
- Hochschild homology definition
- Cyclic homology definition
- Koszul algebra definition
- Koszul duality concept
- Gerstenhaber algebra definition
- Deformation of algebras concept
- Deformation quantization concept
- Kontsevich formality theorem statement
- Algebraic K-theory concept
- Grothendieck group definition
Representations of algebras 18 of 18
- Quiver definition
- Representation of a quiver definition
- Gabriel's theorem statement
- Dynkin quiver definition
- Kac's theorem statement
- Auslander–Reiten theory concept
- Auslander–Reiten quiver definition
- Almost split sequence definition
- Tilting theory concept
- Bernstein–Gelfand–Ponomarev reflection functors concept
- Cluster algebra definition
- Cartan matrix of an algebra definition
- Nakayama algebra definition
- Cellular algebra definition
- Hecke algebra definition
- Temperley–Lieb algebra definition
- Group representation concept
- Modular representation theory concept
Orders 6 of 6
- Order (ring theory) definition
- Maximal order definition
- Eichler order definition
- Hurwitz quaternion order example
- Hurwitz quaternions object
- Jordan–Zassenhaus theorem statement
Hopf algebras and quantum groups 18 of 18
- Coalgebra definition
- Bialgebra definition
- Hopf algebra definition
- Antipode definition
- Comodule definition
- Sweedler notation concept
- Hopf module definition
- Integral of a Hopf algebra definition
- Larson–Sweedler theorem statement
- Nichols–Zoeller theorem statement
- Cartier–Milnor–Moore theorem statement
- Quasitriangular Hopf algebra definition
- Quantum group definition
- Quantum enveloping algebra definition
- Yang–Baxter equation definition
- Ribbon Hopf algebra definition
- Taft algebra example
- Nichols algebra definition
Rings with additional structure 9 of 9
- Graded ring definition
- Filtered algebra definition
- Superalgebra definition
- Differential graded algebra definition
- Ring with involution definition
- Derivation definition
- Banach algebra definition
- Topological ring definition
- Jacobson topology definition
Conditions on elements 5 of 5
- von Neumann regular ring definition
- Unit-regular ring definition
- Clean ring definition
- Boolean ring definition
- Jacobson's conjecture conjecture
Generalizations of rings 5 of 5
- Semiring definition
- Near-ring definition
- Nonassociative ring definition
- Jordan algebra definition
- Octonions object
Computation 1 of 1
- Noncommutative Gröbner basis concept
More ideas in this subject
Concepts 23
- External direct sum
- Finite ring
- Finitely generated module
- Submodule
- Product of rings
- Unitization
- dg category
- Group of units of a ring
- Idempotence
- Involution
- Kernel of a ring homomorphism
- Ring isomorphism
- Bar resolution
- Group algebra
- Hopf algebra structure on cohomology
- Symmetric algebra
- Linear topology
- Near-field
- Tensor product of modules
- Subalgebra
- Partially ordered ring
- Idempotent semiring
- Kleene algebra
Theorems and results 14
- Third isomorphism theorem for vector spaces
- von Neumann coordinatization theorem
- A ring homomorphism is injective iff its kernel is zero
- Correspondence theorem for rings
- Second isomorphism theorem for vector spaces
- Yoneda Ext and extensions
- First isomorphism theorem for linear maps
- Third isomorphism theorem for rings
- Universal property of the quotient ring
- Second isomorphism theorem for rings
- First isomorphism theorem for rings
- Akizuki–Hopkins–Levitzki theorem
- Jordan–Hölder theorem for modules
- Tsen's theorem
Examples 5
Objects 3
Definitions 187
- Module over a ring
- Dynkin quiver
- External direct sum
- Finite ring
- Finitely generated module
- Free module
- Quiver
- Ring
- Semiring
- Submodule
- Antipode
- Dedekind-finite ring
- Essential submodule
- Idempotent element
- Incidence algebra
- Integral of a Hopf algebra
- Laurent polynomial ring
- Left ideal
- Monoid ring
- Morita invariant
- Nilpotent element
- Noncommutative ring
- Opposite ring
- Prime ring
- Product of rings
- Quantum group
- Quasitriangular Hopf algebra
- Ribbon Hopf algebra
- Ring homomorphism
- Simple module
- Simple ring
- Stably finite ring
- Subring
- Tensor algebra
- Unit of a ring
- Unitization
- Yang–Baxter equation
- Zero divisor
- Bimodule
- Center of a ring
- Cluster algebra
- Complete set of orthogonal idempotents
- Deformation of algebras
- Degree of a central simple algebra
- dg category
- Eilenberg swindle
- Gerstenhaber algebra
- Global dimension
- Group of units of a ring
- Hereditary ring
- Hopf algebra
- Idempotence
- Invariant basis number
- Involution
- Kernel of a ring homomorphism
- Morita equivalence
- Ore condition
- Quasi-Frobenius ring
- Radical of a module
- Ring isomorphism
- Self-injective ring
- Semisimple module
- Serial ring
- Skew polynomial ring
- Socle of a module
- Sweedler notation
- Two-sided ideal
- Uniserial module
- Almost split sequence
- Artinian module
- Artinian ring
- Associative algebra
- Auslander–Reiten quiver
- Bar resolution
- Bialgebra
- Brown–McCoy radical
- Cellular algebra
- Central simple algebra
- Clean ring
- Coalgebra
- Comodule
- Crossed product algebra
- Cyclic algebra
- Cyclic homology
- Endomorphism ring
- Filtered algebra
- Frobenius algebra
- Group algebra
- Hopf algebra structure on cohomology
- Hopf module
- Koszul algebra
- Koszul duality
- Levitzki radical
- Maximal order
- Near-ring
- Prime ideal in a noncommutative ring
- Progenerator
- Projective cover
- Quantum enveloping algebra
- Quaternion algebra
- Quotient ring
- Representation of a quiver
- Rng
- Semihereditary ring
- Semilocal ring
- Semiprimitive ring
- Superalgebra
- Symmetric algebra
- Temperley–Lieb algebra
- Tensor product of algebras
- Uniform module
- Weyl algebra
- Bernstein–Gelfand–Ponomarev reflection functors
- Deformation quantization
- Derivation
- Direct limit of rings
- Eichler order
- Goldie ring
- Group ring
- Growth of algebras
- Injective module
- Kurosh–Amitsur radical theory
- Lifting idempotents
- Linear topology
- Maximal subfield
- Morita duality
- Nakayama algebra
- Near-field
- Order (ring theory)
- Perfect ring
- Period and index
- Polynomial identity ring
- Prime radical
- Primitive ring
- Projective module
- Ring with involution
- Semiprime ring
- Semisimple ring
- Skew group ring
- Splitting field of a central simple algebra
- Tensor product of modules
- Universal enveloping algebra
- Upper nilradical
- Weak dimension
- Algebraic K-theory
- Auslander–Reiten theory
- Cartan matrix of an algebra
- Classical ring of quotients
- Faithful module
- Free algebra
- Gelfand–Kirillov dimension
- Generic matrix algebra
- Hochschild homology
- Indecomposable module
- Jacobson radical
- Nil ideal
- Nilpotent ideal
- Noetherian module
- Ore extension
- Ore localization
- Path algebra
- Semiprimary ring
- Separable algebra
- Smash product
- Cohn localization
- Flat module
- Krull dimension of a noncommutative ring
- Leavitt path algebra
- Primitive ideal
- Subalgebra
- Tilting theory
- Differential graded algebra
- Nichols algebra
- Noncommutative Gröbner basis
- Ring of differential operators
- Semiperfect ring
- Brauer group
- von Neumann regular ring
- Unit-regular ring
- Length of a module
- Azumaya algebra
- Central polynomial
- Partially ordered ring
- Idempotent semiring
- Jacobson topology
- Kleene algebra
- Topological ring