Commutators with finite spectrum
The purpose of this paper is to study derivations d, d′ defined on a Banach algebra A such that the spectrum σ([dx,d′x]) is finite for all x ∈ A. In particular we show that if the algebra is semisimple, then there exists an element a in the socle of A such that [d,d′] is the inner derivation implemented by a.
The Lower Socle and Finite Rank Elementary Operators
Abstract We define the lower socle of a semiprime algebra 𝒜 as the sum of all minimal left ideals 𝒜e where e is a minimal idempotent such that the division algebra e𝒜e is finite dimensional. We study the connection between the condition that the elements a k , b k , 1 ≤ k ≤ n, lie in the lower socle of 𝒜 and the condition that the elementary operator x ↦ a 1 xb 1 + ċ + a n xb n has finite rank. As an application we obtain some results on derivations certain of whose powers have finite rank.
Automorphisms and Derivations of Associative Rings
1. Structure of Rings.- 1.1 Baer Radical and Semiprimeness.- 1.2 Automorphism Groups and Lie Differential Algebras.- 1.3 Bergman-Isaacs Theorem. Shelter Integrality.- 1.4 Martindale Ring of Quotients.- 1.5 The Generalized Centroid of a Semiprime Ring.- 1.6 Modules over a Generalized Centroid.- 1.7 Extension of Automorphisms to a Ring of Quotients. Conjugation Modules.- 1.8 Extension of Derivations to a Ring of Quotients.- 1.9 The Canonical Sheaf of a Semiprime Ring.- 1.10 Invariant Sheaves.- 1.11 The Metatheorem.- 1.12 Stalks of Canonical and Invariant Sheaves.- 1.13 Martindale's Theorem.- 1.14 Quite Primitive Rings.- 1.15 Rings of Quotients of Quite Primitive Rings.- 2. On Algebraic Independence of Automorphisms And Derivations.- 2.0 Trivial Algebraic Dependences.- 2.1 The Process of Reducing Polynomials.- 2.2 Linear Differential Identities with Automorphisms.- 2.3 Multilinear Differential Identities with Automorphisms.- 2.4 Differential Identities of Prime Rings.- 2.5 Differential Identities of Semiprime Rings.- 2.6 Essential Identities.- 2.7 Some Applications: Galois Extentions of Pi-Rings Algebraic Automorphisms and Derivations Associative Envelopes of Lie-Algebras of Derivations.- 3. The Galois Theory of Prime Rings (The Case Of Automorphisms).- 3.1 Basic Notions.- 3.2 Some Properties of Finite Groups of Outer Automorphisms.- 3.3 Centralizers of Finite-Dimensional Algebras.- 3.4 Trace Forms.- 3.5 Galois Groups.- 3.6 Maschke Groups. Prime Dimensions.- 3.7 Bimodule Properties of Fixed Rings.- 3.8 Ring of Quotients of a Fixed Ring.- 3.9 Galois Subrings for M-Groups.- 3.10 Correspondence Theorems.- 3.11 Extension of Isomorphisms.- 4. The Galois Theory of Prime Rings (The Case Of Derivations).- 4.1 Duality for Derivations in the Multiplication Algebra.- 4.2 Transformation of Differential Forms.- 4.3 Universal Constants.- 4.4 Shirshov Finiteness.- 4.5 The Correspondence Theorem.- 4.6 Extension of Derivations.- 5. The Galois Theory of Semiprime Rings.- 5.1 Essential Trace Forms.- 5.2 Intermediate Subrings.- 5.3 The Correspondence Theorem for Derivations.- 5.4 Basic Notions of the Galois Theory of Semiprime Rings (the case of automorphisms).- 5.5 Stalks of an Invariant Sheaf for a Regular Group. Homogenous Idempotents.- 5.6 Principal Trace Forms.- 5.7 Galois Groups.- 5.8 Galois Subrings for Regular Closed Groups.- 5.9 Correspondence and Extension Theorems.- 5.10 Shirshov Finiteness. The Structure of Bimodules.- 6. Applications.- 6.1 Free Algebras.- 6.2 Noncommutative Invariants.- 6.3 Relations of a Ring with Fixed Rings.- A. Radicals of Algebras.- B. Units, Semisimple Artinian Rings, Essential Onesided Ideals.- C. Primitive Rings.- D. Quite Primitive Rings.- E. Goldie Rings.- F. Noetherian Rings.- G. Simple and Subdirectly Indecomposable Rings.- H. Prime Ideals. Montgomery Equivalence.- I. Modular Lattices.- J. The Maximal Ring of Quotients.- 6.4 Relations of a Semiprime Ring with Ring of Constants.- 6.5 Hopf Algebras.- References.