ADVANCES IN THE THEORY OF LARGE COOPERATIVE GAMES AND APPLICATIONS TO CLUB THEORY : THE SIDE PAYMENTS CASE

In a series of papers (Kovalenkov and Wooders 2001a, Games and Economic Behavior, 2001b,Mathematics of Operations Research, and 1997, Journal of Economic Theory to appear), the authors have developed the framework of parameterized collections of games and also that of parameterized collections of economies with clubs. These papers apply to collections of games with nontransferable utility and similarly to economies with clubs and general preferences. The game theoretic framework encompasses the earlier `pregame' framework (cf., Wooders 1994b Econometrica) and also earlier models of economies with clubs and with possibly multiple memberships in clubs (cf. Shubik and Wooders 1982). In this paper, we consider the special case of games with side payments and illustrate the application of our more general results in this special, and much simpler but still important, framework. The motivation for this line of research is developed and application to environmental problems is discussed.cooperative games ; clubs ; core ; approximate cores ; widespread externalities ; multiple memberships ; local public goods

Semantic Query Reformulation in Social PDMS

We consider social peer-to-peer data management systems (PDMS), where each peer maintains both semantic mappings between its schema and some acquaintances, and social links with peer friends. In this context, reformulating a query from a peer's schema into other peer's schemas is a hard problem, as it may generate as many rewritings as the set of mappings from that peer to the outside and transitively on, by eventually traversing the entire network. However, not all the obtained rewritings are relevant to a given query. In this paper, we address this problem by inspecting semantic mappings and social links to find only relevant rewritings. We propose a new notion of 'relevance' of a query with respect to a mapping, and, based on this notion, a new semantic query reformulation approach for social PDMS, which achieves great accuracy and flexibility. To find rapidly the most interesting mappings, we combine several techniques: (i) social links are expressed as FOAF (Friend of a Friend) links to characterize peer's friendship and compact mapping summaries are used to obtain mapping descriptions; (ii) local semantic views are special views that contain information about external mappings; and (iii) gossiping techniques improve the search of relevant mappings. Our experimental evaluation, based on a prototype on top of PeerSim and a simulated network demonstrate that our solution yields greater recall, compared to traditional query translation approaches proposed in the literature.Comment: 29 pages, 8 figures, query rewriting in PDM

The Last Scientific Revolution

Critically growing problems of fundamental science organisation and content are analysed with examples from physics and emerging interdisciplinary fields. Their origin is specified and new science structure (organisation and content) is proposed as a unified solution