On the nuclear dimension of strongly purely infinite C*-algebras

Supported by: SFB 878 Groups, Geometry and Actions and EPSRC grant EP/N00874X/1Peer reviewedPublisher PD

Equivariant property (SI) revisited

We revisit Matui-Sato's notion of property (SI) for C*-algebras and C*-dynamics. More specifically, we generalize the known framework to the case of C*-algebras with possibly unbounded traces. The novelty of this approach lies in the equivariant context, where none of the previous work allows one to (directly) apply such methods to actions of amenable groups on highly non-unital C*-algebras, in particular to establish equivariant Jiang-Su stability. Our main result is an extension of an observation by Sato: For any countable amenable group $\Gamma$ and any non-elementary separable simple nuclear C*-algebra $A$ with strict comparison, every $\Gamma$-action on $A$ has equivariant property (SI). A more general statement involving relative property (SI) for inclusions into ultraproducts is proved as well. As a consequence we show that if $A$ also has finitely many rays of extremal traces, then every $\Gamma$-action on $A$ is equivariantly Jiang-Su stable. We moreover provide applications of the main result to the context of strongly outer actions, such as a generalization of Nawata's classification of strongly outer automorphisms on the (stabilized) Razak-Jacelon algebra.Comment: v4 36 pages; this version has been accepted at Analysis & PD

The Rokhlin dimension of topological Z^m-actions

We study the topological variant of Rokhlin dimension for topological dynamical systems (X,{\alpha},Z^m) in the case where X is assumed to have finite covering dimension. Finite Rokhlin dimension in this sense is a property that implies finite Rokhlin dimension of the induced action on C*-algebraic level, as was discussed in a recent paper by Ilan Hirshberg, Wilhelm Winter and Joachim Zacharias. In particular, it implies under these conditions that the transformation group C*-algebra has finite nuclear dimension. Generalizing a result of Yonatan Gutman, we show that free Z^m-actions on finite dimensional spaces satisfy a strengthened version of the so-called marker property, which yields finite Rokhlin dimension for said actions.Comment: 27 pages; with minor corrections in some proof

A short note on the continuous Rokhlin property and the universal coefficient theorem

Let $G$ be a metrizable compact group, $A$ a separable C*-algebra and $\alpha$ a strongly continuous action of $G$ on $A$. Provided that $\alpha$ satisfies the continuous Rokhlin property, we show that the property of satisfying the UCT in E-theory passes from $A$ to the crossed product C*-algebra $A\rtimes_\alpha G$ and the fixed point algebra $A^\alpha$. This extends a result by Gardella in the case that $G$ is the circle and $A$ is nuclear. For circle actions on separable, unital C*-algebras with the continuous Rokhlin property, we establish a connection between the $E$-theory equivalence class of the coefficient algebra $A$ and the fixed point algebra $A^\alpha$.Comment: 7 page

Equivariant Kirchberg-Phillips-type absorption for amenable group actions

We show an equivariant Kirchberg-Phillips-type absorption theorem for pointwise outer actions of discrete amenable groups on Kirchberg algebras with respect to natural model actions on the Cuntz algebras $\mathcal{O}_\infty$ and $\mathcal{O}_2$. This generalizes results known for finite groups and poly-$\mathbb{Z}$ groups. The model actions are shown to be determined, up to strong cocycle conjugacy, by natural abstract properties, which are verified for some examples of actions arising from tensorial shifts. We also show the following homotopy rigidity result, which may be understood as a precursor to a general Kirchberg-Phillips-type classification theory: If two outer actions of an amenable group on a unital Kirchberg algebra are equivariantly homotopy equivalent, then they are conjugate. This marks the first C*-dynamical classification result up to cocycle conjugacy that is applicable to actions of all amenable groups.Comment: v3 42 pages; this version has been accepted for publication in Communications in Mathematical Physic

"Co-Operative Identity" - A Theoretical Concept for Dynamic Analysis of Practical Co-Operation: The Dutch Case

The "concept of the co-operative identity" (consisting from the definition, aims and functions of cooperatives and the so-termed co-operative principles) serves as a general theoretical background for the economic analysis of agricultural co-operation. The development of Dutch dairy co-operatives is used as a case study example, which suitably illustrates and represents the processes taking place in the European Union. Some suggestions for further research on the co-operative identity according to each country and different branches and sectors in order to see the substance of co-operation from different economic and non-economic aspects are proposed.agriculture, co-operative, identity, principles, strategy, Agribusiness, Q13, L14, L22,

Integration of small and medium size farmers by co-operatives in the Hungarian fruit and vegetable sector - a case study

The main co-ordinators/channels used in Hungarian fruit and vegetable supply chain are the following: local market, wholesale markets, production co-operatives, marketing cooperatives, producers organisation, processing industry, wholesalers and retailers. Different retail chains gain a progressively larger share of the fresh fruit and vegetable market. It is very important, therefore, that the farmers have to use marketing channels which could give them the strengths (countervailing power) of more concentrated organisations. In this case study, we examine the integration role of Mórakert Purchasing and Service Co-operative, in Mórahalom in county Csongrád which can be found in the southern east part of Hungary. The Morakert co-operative active in the fruit and vegetable sector and it was the first officially acknowledged Producers Organisation (PO) in Hungary. It works as a very successful cooperative (e.g. in terms of increasing annual turnover and membership) thus being a good example for a number of emerging producer organisations.fruit and vegetable, integration, co-operatives, Producers Organisation, Hungary, Agribusiness, Farm Management,

“Co-operative identityâ€: A theoretical concept for economic analysis of practical co-operation dynamics

Farmers’ problems and co-ordination of agricultural activities cannot be solved simply by EU and/or government support, or by private market co-ordination institutions. Emerging producer groups and co-operatives seem vital in achieving bargaining power. Theoretically, and according to Western European (Dutch, Danish etc.) and US practical experience, one of the major important private institutions that can strengthen producers and help co-ordinate (agricultural) chains is the co-operative entity. To fulfill the basic co-operative aims and to compete in a more market-oriented environment (e.g. more liberal agricultural policies, opening European and world market, etc.) they will initiate new marketing strategies. To implement such new marketing strategies, co-ops have to collect more risk capital and in Western European agricultural co-operatives this is currently precipitating some fundamental financial and organisational changes. To retain the basic co-operative character, they are undertaking internal and external organisational changes, which in a number of cases will create so-called new co-operative structures/models. In this paper the “co-operative identity†concept (meaning the aims and functions of co-operatives, as well as the so-termed co-operative principles) is proposed to serve as a general theoretical background to evaluate economically the flexibility of (agricultural) cooperation. Also proposed is a new, interdisciplinary research focus (including comprehensive theoretical overview). This new focus examines the substance of co-operation and emphasises the importance of combining insights across the social sciences. It uses the results and common findings of economics, law, marketing, financing, organisational studies, management sciences (“hard†sciences), and also some elements of philosophy, psychology, sociology etc. (“soft†disciplines). Also recommended are some suggestions for further comparative research on the “co-operative identityâ€. This is carried out according to each country and different branches and sectors to observe the substance and dynamics of co-operation from different economic and non-economic aspects.Co-operation, co-operative identity, co-operative principles, strategy, marketing, co-ordination, vertical integration, agriculture, Farm Management, Marketing,

CHANGES IN THE STRUCTURE OF AGRICULTURAL PRODUCTION, FARM STRUCTURE AND INCOME IN HUNGARY IN THE PERIOD OF 2004-2006

This study reviews the major changes in Hungarian agriculture that occurred between 2004 and 2006. Subjects investigated will include the structural shift towards crop production, the drastic decrease in the foreign food trade balance, and agricultures deteriorating capacity to sustain and retain a rural population. (Hereinafter: sustaining and retaining capacity of agriculture). The author will diagnose related problems, but will not offer any solutions. Nevertheless, he will present a perspective stipulating that Hungarian agricultures chronic problems require an agricultural strategy based on political consensus.EU accession, structural change, foreign food trade, sustaining and retaining capacity of agriculture, agricultural strategy, Farm Management,