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2009

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Articles 6331 - 6337 of 6337

Full-Text Articles in Physical Sciences and Mathematics

Event-Detecting Multi-Agent Mdps: Complexity And Constant-Factor Approximation, Akshat Kumar, S. Zilberstein Jan 2009

Event-Detecting Multi-Agent Mdps: Complexity And Constant-Factor Approximation, Akshat Kumar, S. Zilberstein

Research Collection School Of Computing and Information Systems

Planning under uncertainty for multiple agents has grown rapidly with the development of formal models such as multi-agent MDPs and decentralized MDPs. But despite their richness, the applicability of these models remains limited due to their computational complexity. We present the class of event-detecting multi-agent MDPs (eMMDPs), designed to detect multiple mobile targets by a team of sensor agents. We show that eMMDPs are NP-Hard and present a scalable 2-approximation algorithm for solving them using matroid theory and constraint optimization. The complexity of the algorithm is linear in the state-space and number of agents, quadratic in the horizon, and exponential …

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Web Social Mining, Hady W. Lauw, Ee Peng Lim Jan 2009

Web Social Mining, Hady W. Lauw, Ee Peng Lim

Research Collection School Of Computing and Information Systems

No abstract provided.

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Continuous Monitoring Of Spatial Queries, Kyriakos Mouratidis Jan 2009

Continuous Monitoring Of Spatial Queries, Kyriakos Mouratidis

Research Collection School Of Computing and Information Systems

No abstract provided.

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Computing Medoids In Large Spatial Datasets, Kyriakos Mouratidis, Dimitris Papadias, Spiros Papadimitriou Jan 2009

Computing Medoids In Large Spatial Datasets, Kyriakos Mouratidis, Dimitris Papadias, Spiros Papadimitriou

Research Collection School Of Computing and Information Systems

In this chapter, we consider a class of queries that arise in spatial decision making and resource allocation applications. Assume that a company wants to open a number of warehouses in a city. Let P be the set of residential blocks in the city. P represents customer locations to be potentially served by the company. At the same time, P also comprises the candidate warehouse locations because the warehouses themselves must be opened in some residential blocks.

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Efficient Valid Scope Computation For Location-Dependent Spatial Queries In Mobile And Wireless Environments, Ken C. K. Lee, Wang-Chien Lee, Hong Va Leong, Brandon Unger, Baihua Zheng Jan 2009

Efficient Valid Scope Computation For Location-Dependent Spatial Queries In Mobile And Wireless Environments, Ken C. K. Lee, Wang-Chien Lee, Hong Va Leong, Brandon Unger, Baihua Zheng

Research Collection School Of Computing and Information Systems

In mobile and wireless environments, mobile clients can access information with respect to their locations by submitting Location-Dependent Spatial Queries (LDSQs) to Location-Based Service (LBS) servers. Owing to scarce wireless channel bandwidth and limited client battery life, frequent LDSQ submission from clients must be avoided. Observing that LDSQs issued from similar client positions would normally return the same results, we explore the idea of valid scope, that represents a spatial area in which a set of LDSQs will retrieve exactly the same query results. With a valid scope derived and an LDSQ result cached at the client side, a client …

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A Comprehensive Study For Rfid Malwares On Mobile Devices, Qiang Yan, Yingjiu Li, Tieyan Li, Robert Huijie Deng Jan 2009

A Comprehensive Study For Rfid Malwares On Mobile Devices, Qiang Yan, Yingjiu Li, Tieyan Li, Robert Huijie Deng

Research Collection School Of Computing and Information Systems

Radio Frequency Identification (RFID) technique has been widely accepted as wireless identification standard in the business world. While RFID technique enables efficient collection of identification information, it also introduces new security risk due to the emerging of RFID malwares. This risk becomes increasingly severe due to the adoption of internet in RFID applications (e.g., track and trace in EPCglobal network) and the use of mobile devices as RFID readers. The prior work to defend the threat of RFID malwares has mainly focused on the protection of front-end tag-reader communications and back-end database systems. Less work has been conducted to defend …

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Quality-Aware Collaborative Question Answering: Methods And Evaluation, Maggy Anastasia Suryanto, Ee Peng Lim, Aixin Sun, Roger Hsiang-Li Chiang Jan 2009

Quality-Aware Collaborative Question Answering: Methods And Evaluation, Maggy Anastasia Suryanto, Ee Peng Lim, Aixin Sun, Roger Hsiang-Li Chiang

Research Collection School Of Computing and Information Systems

Community Question Answering (QA) portals contain questions and answers contributed by hundreds of millions of users. These databases of questions and answers are of great value if they can be used directly to answer questions from any user. In this research, we address this collaborative QA task by drawing knowledge from the crowds in community QA portals such as Yahoo! Answers. Despite their popularity, it is well known that answers in community QA portals have unequal quality. We therefore propose a quality-aware framework to design methods that select answers from a community QA portal considering answer quality in addition to …

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