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ÐIn current distributed systems, the notion of mobility is emerging in many forms and applications. Mobility arises naturally in wireless computing since the location of users changes as they move. Besides mobility in wireless computing, software mobile agents are another popular form of moving objects. Locating objects, i.e., identifying their current(More)
Result diversification has recently attracted much attention as a means of increasing user satisfaction in recommender systems and web search. Many different approaches have been proposed in the related literature for the diversification problem. In this paper, we survey, classify and comparatively study the various definitions, algorithms and metrics for(More)
Preferences have been traditionally studied in philosophy, psychology, and economics and applied to decision making problems. Recently, they have attracted the attention of researchers in other fields, such as databases where they capture soft criteria for queries. Databases bring a whole fresh perspective to the study of preferences, both computational and(More)
It is expected that in the near future millions of users will have access to on-line distributed databases through mobile computers. This possibility raises challenging questions regarding the consistency and availability of data. To deal with the frequent, predictable and varying in degree disconnections that occur in a mobile environment, we introduce(More)
Recently, push-based delivery has attracted considerable attention as a means of disseminating information to large client populations in both wired and wireless settings. In this paper, we address the problem of ensuring the consistency and currency of client read-only transactions in the presence of updates. To this end, additional control information is(More)
It is expected that in the near future millions of users will have access to on-line distributed databases through mobile computers. The restrictions imposed by the nature of the wireless medium and the resulting mobility of data consumers and data producers make traditional transaction models inadequate. In this paper , we investigate means for providing(More)
Peer-to-peer (P2P) systems are gaining increasing popularity as a scalable means to share data among a large number of autonomous nodes. In this paper, we consider the case in which the nodes in a P2P system store XML documents. We propose a fully decentralized approach to the problem of routing path queries among the nodes of a P2P system based on(More)
Advances in wireless network technology and the continuously increasing number of users of hand-held terminals make the latter a possible channel for o€ering personalized services to mobile users and give pace to the rapid development of mobile electronic commerce (MEC). MEC operates partially in a di€erent environment than Internet e-commerce due to the(More)
ÐThe popularity of the Web as a universal access mechanism for network information has created the need for developing web-based DBMS client/server applications. However, the current commercial applet-based approaches for accessing database systems offer limited flexibility, scalability, and robustness. In this paper, we propose a new framework for(More)
Recently, broadcasting has attracted considerable attention as a means of disseminating information to large client populations in both wired and wireless settings. In this paper, we exploit versions to increase the concurrency of client transactions in the presence of updates. We consider three alternative mediums for storing versions: (a) the air: older(More)