On Amenable Banach Algebras

In this paper we extend the concept of amenable algebra given by Jobnsonin[3]to n-amenable algebra.We prove several properties which are extensionof1-amenable algebras appeared in[3]and[4],and we give a sufficientcondition for a Banach algebra being2-amenable.     

Real Banach ✶ Algebras

In this paper, we study real Banach ✶ algebras systematically. We present the right form of Pták's inequality [1,4] in the real case, and generalize the results of Vukman in [3] to the general case (algebras with or without an identity). Moreover, this paper is a real analogue of Pták's work [1] in the complex case. Received February 22, 2000, Accepted March 14, 2000     

On Certain Filters in Lattice Implication Algebras

ＯｎＣｅｒｔａｉｎＦｉｌｔｅｒｓｉｎＬａｔｔｉｃｅＩｍｐｌｉｃａｔｉｏｎＡｌｇｅｂｒａｓＬｉｕＪｕｎ；ＸｕＹａｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＡｐｐｌｉｅｄＭａｔｈｅｍａｔｉｃｓ，ＳｏｕｔｈｗｅｓｔＪｉａｏｔｏｎｇＵｎｉｖｅｒｓｉｔｙ，Ｃｈｅｎｇｄｕ，...     

On approximation of functions in terms of Φ-variation

Получен аналог теоре мы Джексона о приближ ении полиномами в метрике Ф-вариации; для некото рых классов функций (в ыпуклых, конечной вариации, с заданным модулем неп рерывности) установл ено соотношение типа сла бой эквивалентности, которое связывает ме жду собой рациональн ые аппроксимации, в этой и равномерной метриках Даны оценкиε-энтропи и в метрике Ф-вариации классов функций с заданным мо дулем Ф-абсолютной непреры вности и с заданным мо дулем непрерывности.     

On groups of type Φ

We define a group G to be of type Φ if it has the property that for every -module G, proj. G < ∞ iff proj. H G < ∞ for every finite subgroup H of G. We conjecture that the type Φ is an algebraic characterization of those groups G which admit a finite dimensional model for , the classifying space for the family of the finite subgroups of G. We also conjecture that the type Φ is equivalent to spli being finite, where spli is the supremum of the projective lengths of the injective -modules. Here we prove certain parts of these conjectures. The project is cofounded by the European Social Fund and National Resources–EPEAK II–Pythagoras. Received: 21 June 2006     

On the Extension Operator in Banach Spaces

In [1], Roper and Suffridge introduced an extension operator. This operator is defined for normalized locally univalent function f on the unit disc U = {z∈C：｜z｜〈1} in C by Фn（f）（z）=（f（z1）,√ f′（z1）z0）, where z = （z1,z0） belongs to the unit ball Bn in Cn, z1∈U, z0 = （z2,...,zn） ∈ C^n-1.     

On the Generalized Virasoro-like Algebras

ＯｎｔｈｅＧｅｎｅｒａｌｉｚｅｄＶｉｒａｓｏｒｏ┐ｌｉｋｅＡｌｇｅｂｒａｓＪｉａＹｕｔｉｎｇ（贾雨亭）（ＤｅｐａｒｔｍｅｎｔｏｆＭａｔｈｅｍａｔｉｃｓ，ＨｅｂｅｉＴｅａｃｈｅｒｓＵｎｉｖｅｒｓｉｔｙ，Ｓｈｉｊｉａｚｈｕａｎｇ，０５００１６）Ｚｈａｎｇ...     

Hyers–Ulam Stability of General Jensen-Type Mappings in Banach Algebras

Using the fixed point method, we prove the Hyers–Ulam stability of homomorphisms in complex Banach algebras and complex Banach Lie algebras and also of derivations on complex Banach algebras and complex Banach Lie algebras for the general Jensen-type functional equation f(α x + β y) + f(α x ? β y) = 2α f(x) for any \({\alpha, \beta \in \mathbb{R}}\) with \({\alpha, \beta \neq 0}\) . Furthermore, we prove the hyperstability of homomorphisms in complex Banach algebras for the above functional equation with α = β = 1.     

A Characterization of Homomorphisms Between Banach Algebras

We show that every unital invertibility preserving linear map from a yon Neumann algebraonto a semi-simple Banach algebra is a Jordan homomorphism;this gives an affirmative answer to aproblem of Kaplansky for all von Neumann algebras.For a unital linear map Φ from a semi-simplecomplex Banach algebra onto another,we also show that the following statements are equivalent:(1)Φ is an homomorphism;(2)Φ is completely invertibihty preserving;(3)Φ is 2-invertibility preserving.     

The Continuity of Epimorphisms of Banach Algebras

ＬｅｔｆｂｅａｌｉｎｅａｒｍａｐｐｉｎｇｆｒｏｍａＢａｎａｃｈｓｐａｃｅＸｔｏａＢａｎａｃｈｓｐａｃｅＹ．Ｔｈｅｎｔｈｅｓｅｐａｒａｔｉｎｇｓｐａｃｅｏｆｆｉｓ（ｆ）＝｛ｙ∈Ｙ：ｔｈｅｒｅｅｘｉｓｔｓａｓｅｑｕｅｎｃｅ（ｘｎ）ｉｎＸｗｉｔｈｘｎ０ａ...     

On Strong Kadison–Singer Algebras

We show that many Kadison–Singer algebras are maximal triangular in all algebras containing them although their definition requires the maximality taken in the class of reflexive algebras. Diagonal-trivial maximal non self-adjoint subalgebras of matrix algebras with lower dimensions are classified.     

On Polynomial Representations of Lie Algebras

We study polynomial representations of finite dimensional (R or C) Lie algebras. As a total classification, we show that there are altogether three types of such nontrivial representations and give their subtle structures.     

Fixed Points and Stability for Quadratic Mappings in β–Normed Left Banach Modules on Banach Algebras

The goal of the present paper is to investigate some new stability results by applying the alternative fixed point of generalized quadratic functional equation $$\begin{array}{ll}f\left(\sum\limits_{i=1}^{n}a_ix_i\right)+{\sum\limits_{i=1}^{n-1}}{\sum\limits_{j=i+1}^{n}}\left[f(a_ix_i+a_jx_j)+2f(a_ix_i-a_jx_j)\right]\\ \qquad \quad = (3n-2){\sum\limits_{i=1}^{n}}a^2_{i}f(x_{i})\end{array}$$ in β–Banach modules on Banach algebras, where ${a_{1},\dots,a_{n}\in \mathbb{Z}{\setminus}\{0\}}$ and some ${\ell\in\{1 , 2 ,\dots, n-1\},}$ a _? ?≠ ±1 and a _n ?=?1, where n is a positive integer greater or at least equal to two.     

On Lie Algebras in the Category of Yetter—Drinfeld Modules

The category of Yetter—Drinfeld modules over a Hopf algebra K (with bijective antipode over a field k) is a braided monoidal category. If H is a Hopf algebra in this category then the primitive elements of H do not form an ordinary Lie algebra anymore. We introduce the notion of a (generalized) Lie algebra in such that the set of primitive elements P(H) is a Lie algebra in this sense. Also the Yetter—Drinfeld module of derivations of an algebra A in is a Lie algebra. Furthermore for each Lie algebra in there is a universal enveloping algebra which turns out to be a Hopf algebra in .     

On Identities in Algebras Q n,λ Generated by Idempotents

We investigate the presence of polynomial identities in the algebras Q _n, generated by n idempotents with the sum e ( and e is the identity of an algebra). We prove that Q _4,2 is an algebra with the standard polynomial identity F ₄, whereas the algebras Q _4,, 2, and Q _n,, n 5, do not have polynomial identities.     

On Properties of the ξ-Function in Semi-finite von Neumann Algebras

Versions of the Birman-Schwinger principle for (relative) trace class perturbation problems of dissipative operators in a semi-finite von Neumann algebra and self-adjoint operators affiliated with the algebra are obtained and applied in the study of the spectral shift function.      

Derived Equivalences for Φ-Cohen–Macaulay Auslander–Yoneda Algebras

In this paper, we introduce a class of algebras called Φ-Cohen–Macaulay Auslander–Yoneda algebras with Φ an admissible set of ?, and construct derived equivalences between these Φ-Cohen–Macaulay Auslander–Yoneda algebras from a given derived equivalence.     

On quasimöbius maps in real Banach spaces

Suppose that E and E′ denote real Banach spaces with dimension at least 2, that D $ \subseteq $ E and D′ $ \subseteq $ E′ are domains, that f: D → D′ is an (M,C)-CQH homeomorphism, and that D is uniform. The aim of this paper is to prove that D′ is a uniform domain if and only if f extends to a homeomorphism $\overline f :\overline D \to {\overline D ^\prime }$ and $\overline f $ is η-QM relative to ?D. This result shows that the answer to one of the open problems raised by Väisälä from 1991 is affirmative.     

On Best Approximations from RS-sets in Complex Banach Spaces

The concept of an RS-set in a complex Banach space is introduced and the problem of best approximation from an RS-set in a complex space is investigated. Results consisting of characterizations, uniqueness and strong uniqueness are established,