This text, drawn from the author's lectures at the University of California at Berkeley, is intended as a textbook for a one-term course in basic ring theory. The material covered includes the Wedderburn-Artin theory of semi-simple rings, Jacobson's theory of the radical representation theory of groups and algebras, prime and semi-prime rings, primitive and semi-primitive rings, division rings, ordered rings, local and semi-local rings, and perfect and semi-perfect rings. By aiming the level of writing at the novice rather than at the expert, and by stressing the role of examples and motivation, the author has produced a text which is suitable not only for use in a graduate course, but also for self-study by other interested graduate students. Numerous exercises are also included. This graduate textbook on rings, fields and algebras is intended for graduate students in mathematics.

A first course in noncommutative rings, by T. Y. Lam. Pp. 385. £37 (pb), £62.50 (hb). 2001. ISBN 0 387 95325 6 (pb), 0 387 95183 0 (hb) (Springer-Verlag).

Determine the value of the variable in each equation.

Basic Algebra = 代数学入門

Let R be a left faithful ringU its right Utumi quotient ring and ρ a dense right ideal of R. An additive map g: ρ → U is called a generalized derivation if there exists a derivation δ of ρ into U such that for all x,y∈ρ. In this note, we prove that there exists an element a∈ U such that for all x ∈ ρ. From this characterization, it is proved that if R is a semiprime ring and if g is a generalized derivation with nilpotent values of bounded index, then g = 0. Analogous results are also obtained for the case of generalized derivations with nilpotent values on Lie ideals or one-sided ideals.

Generalized derivations of left faithful rings

A map $f$ on a ring $\cal A$ is said to be commuting if $f(x)$ commutes with $x$ for every $x\in \cal A$. The paper surveys the development of the theory of commuting maps and their applications. The following topics are discussed: commuting derivations, commuting additive maps, commuting traces of multiadditive maps, various generalizations of the notion of a commuting map, and applications of results on commuting maps to different areas, in particular to Lie theory.

/pdf/commuting-maps-a-survey-3jqw67542b.pdf

Commuting maps: a survey

Commuting maps on a class of algebras called triangular algebras are investigated. In particular, sufficient conditions are given such that every commuting map L on such an algebra is of the form L(a) = ax+h(a), where x lies in the center of the algebra and h is a linear map from the algebra to its center.

Commuting Maps of Triangular Algebras

Identities with a single skew derivation

A ring R is called Armendariz if, whenever in R[x], a i b j  = 0 for all i and j In this paper, some “relatively maximal” Armendariz subrings of matrix rings are identified, and a necessary and sufficient condition for a trivial extension to be Armendariz is obtained Consequently, new families of Armendariz rings are presented

Armendariz and Reduced Rings

A module is defined to be an automorphism-invariant module if it is invariant under automorphisms of its injective hull. Quasi-injective modules and, more generally, pseudo-injective modules are all automorphism-invariant. Here we develop basic properties of these modules, and discuss when an automorphism-invariant module is quasi-injective or injective. Some known results on quasi-injective and pseudo-injective modules are extended.

Modules which are invariant under automorphisms of their injective hulls

Let R be a prime ring which is not commutative, with maximal symmetric ring of quotients Q ms (R), and let τ be an anti-automorphism of R. An additive map δ: R → Q ms (R) is called a Jordan τ-derivation if δ(x 2) = δ(x)x τ + xδ(x) for all x ∈ R. A Jordan τ-derivation of R is called X-inner if it is of the form x → ax τ − xa for x ∈ R, where a ∈ Q ms (R). It is proved that any Jordan τ-derivation of R is X-inner if either R is not a GPI-ring or R is a PI-ring except when charR = 2 and dim  C RC = 4, where C is the extended centroid of R.

Tsiu-Kwen Lee

Papers

Generalized derivations of left faithful rings

Identities with a single skew derivation

Armendariz and Reduced Rings

Modules which are invariant under automorphisms of their injective hulls

Jordan τ-derivations of Prime Rings