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Constraint-Based Dynamic Programming For Decentralized Pomdps With Structured Interactions, Akshat Kumar, Shlomo Zilberstein May 2009

Constraint-Based Dynamic Programming For Decentralized Pomdps With Structured Interactions, Akshat Kumar, Shlomo Zilberstein

Research Collection School Of Computing and Information Systems

Decentralized partially observable MDPs (DEC-POMDPs) provide a rich framework for modeling decision making by a team of agents. Despite rapid progress in this area, the limited scalability of solution techniques has restricted the applicability of the model. To overcome this computational barrier, research has focused on restricted classes of DEC-POMDPs, which are easier to solve yet rich enough to capture many practical problems. We present CBDP, an efficient and scalable point-based dynamic programming algorithm for one such model called ND-POMDP (Network Distributed POMDP). Specifically, CBDP provides magnitudes of speedup in the policy computation and generates better quality solution for all …


Dynamic Programming Approximations For Partially Observable Stochastic Games, Akshat Kumar, Shlomo Zilberstein May 2009

Dynamic Programming Approximations For Partially Observable Stochastic Games, Akshat Kumar, Shlomo Zilberstein

Research Collection School Of Computing and Information Systems

Partially observable stochastic games (POSGs) provide a rich mathematical framework for planning under uncertainty by a group of agents. However, this modeling advantage comes with a price, namely a high computational cost. Solving POSGs optimally quickly becomes intractable after a few decision cycles. Our main contribution is to provide bounded approximation techniques, which enable us to scale POSG algorithms by several orders of magnitude. We study both the POSG model and its cooperative counterpart, DEC-POMDP. Experiments on a number of problems confirm the scalability of our approach while still providing useful policies.


Joint Ranking For Multilingual Web Search, Wei Gao, Cheng Niu, Ming Zhou, Kam-Fai Wong Apr 2009

Joint Ranking For Multilingual Web Search, Wei Gao, Cheng Niu, Ming Zhou, Kam-Fai Wong

Research Collection School Of Computing and Information Systems

Ranking for multilingual information retrieval (MLIR) is a task to rank documents of different languages solely based on their relevancy to the query regardless of query’s language. Existing approaches are focused on combining relevance scores of different retrieval settings, but do not learn the ranking function directly. We approach Web MLIR ranking within the learning-to-rank (L2R) framework. Besides adopting popular L2R algorithms to MLIR, a joint ranking model is created to exploit the correlations among documents, and induce the joint relevance probability for all the documents. Using this method, the relevant documents of one language can be leveraged to improve …


Describing Fuzzy Sets Using A New Concept: Fuzzify Functor, Kexin Wei, Zhaoxia Wang, Quan Wang Apr 2009

Describing Fuzzy Sets Using A New Concept: Fuzzify Functor, Kexin Wei, Zhaoxia Wang, Quan Wang

Research Collection School Of Computing and Information Systems

This paper proposed a fuzzify functor as an extension of the concept of fuzzy sets. The fuzzify functor and the first-order operated fuzzy set are defined. From the theory analysis, it can be observed that when the fuzzify functor acts on a simple crisp set, we get the first order fuzzy set or type-1 fuzzy set. By operating the fuzzify functor on fuzzy sets, we get the higher order fuzzy sets or higher type fuzzy sets and their membership functions. Using the fuzzify functor we can exactly describe the type-1 fuzzy sets, type-2 fuzzy sets and higher type or higher …


The Digital Wallet: Opportunities And Prototypes, Rajesh Krishna Balan, Narayanasamy Ramasubbu Apr 2009

The Digital Wallet: Opportunities And Prototypes, Rajesh Krishna Balan, Narayanasamy Ramasubbu

Research Collection School Of Computing and Information Systems

Example digital wallet applications support secure P2P mobile cash transactions and alleviate point-of-sale confusion for consumers using multiple payment, discount, and loyalty cards.


Efficient Evaluation Of Multiple Preference Queries, Hou U Leong, Nikos Mamaoulis, Kyriakos Mouratidis Apr 2009

Efficient Evaluation Of Multiple Preference Queries, Hou U Leong, Nikos Mamaoulis, Kyriakos Mouratidis

Research Collection School Of Computing and Information Systems

Consider multiple users searching for a hotel room, based on size, cost, distance to the beach, etc. Users may have variable preferences expressed by different weights on the attributes of the searched objects. Although individual preference queries can be evaluated by selecting the object in the database with the highest aggregate score, in the case of multiple requests at the same time, a single object cannot be assigned to more than one users. The challenge is to compute a fair 1-1 matching between the queries and a subset of the objects. We model this as a stable-marriage problem and propose …


Exploring Hierarchically Organized Georeferenced Multimedia Annotations In The Mobitop System, Thi Nhu Quynh Kim, Khasfariyati Razikin, Dion Hoe-Lian Goh, Yin Leng Theng, Quang Minh Nguyen, Ee-Peng Lim, Aixin Sun, Chew Hung Chang, Kalyani Chatterjea Apr 2009

Exploring Hierarchically Organized Georeferenced Multimedia Annotations In The Mobitop System, Thi Nhu Quynh Kim, Khasfariyati Razikin, Dion Hoe-Lian Goh, Yin Leng Theng, Quang Minh Nguyen, Ee-Peng Lim, Aixin Sun, Chew Hung Chang, Kalyani Chatterjea

Research Collection School Of Computing and Information Systems

We introduce MobiTOP, a map-based interface for accessing hierarchically organized georeferenced annotations. Each annotation contains multimedia content associated with a location, and users are able to annotate existing annotations, in effect creating a hierarchy. MobiTOPs interface was designed using a participatory design methodology to ensure that the user interface meets the needs of potential users. A pilot study to compare the MobiTOP interface with a space-filling thumbnail (SFT) interface suggested that participants preferred the MobiTOP design for accessing annotations even though the SFT interface was conceptually easier to understand resources.


Rsa-Based Certificateless Public Key Encryption, Junzuo Lai, Robert H. Deng, Shengli Liu, Weidong Kou Apr 2009

Rsa-Based Certificateless Public Key Encryption, Junzuo Lai, Robert H. Deng, Shengli Liu, Weidong Kou

Research Collection School Of Computing and Information Systems

Certificateless Public Key Cryptography was first introduced by Al-Riyami and Paterson in order to eliminate the inherent key-escrow problem of Identity-Based Cryptography. In this paper, we present a new practical construction of certificateless public key encryption scheme without paring. Our scheme is, in the random oracle model, provably secure under the assumption that the RSA problem is intractable.


Efficient Mining Of Closed Repetitive Gapped Subsequences From A Sequence Database, Bolin Ding, David Lo, Jiawei Han, Siau-Cheng Khoo Apr 2009

Efficient Mining Of Closed Repetitive Gapped Subsequences From A Sequence Database, Bolin Ding, David Lo, Jiawei Han, Siau-Cheng Khoo

Research Collection School Of Computing and Information Systems

There is a huge wealth of sequence data available, for example, customer purchase histories, program execution traces, DNA, and protein sequences. Analyzing this wealth of data to mine important knowledge is certainly a worthwhile goal. In this paper, as a step forward to analyzing patterns in sequences, we introduce the problem of mining closed repetitive gapped subsequences and propose efficient solutions. Given a database of sequences where each sequence is an ordered list of events, the pattern we would like to mine is called repetitive gapped subsequence, which is a subsequence (possibly with gaps between two successive events within it) …


Opaque: Protecting Path Privacy In Directions Search, Ken C. K. Lee, Wang-Chien Lee, Hong Va Leong, Baihua Zheng Apr 2009

Opaque: Protecting Path Privacy In Directions Search, Ken C. K. Lee, Wang-Chien Lee, Hong Va Leong, Baihua Zheng

Research Collection School Of Computing and Information Systems

Directions search returns the shortest path from a source to a destination on a road network. However, the search interests of users may be exposed to the service providers, thus raising privacy concerns. For instance, a path query that finds a path from a resident address to a clinic may lead to a deduction about "who is related to what disease". To protect user privacy from accessing directions search services, we introduce the OPAQUE system, which consists of two major components: (1) an obfuscator that formulates obfuscated path queries by mixing true and fake sources/destinations; and (2) an obfuscated path …


An Incremental Threshold Method For Continuous Text Search Queries, Kyriakos Mouratidis, Hwee Hwa Pang Apr 2009

An Incremental Threshold Method For Continuous Text Search Queries, Kyriakos Mouratidis, Hwee Hwa Pang

Research Collection School Of Computing and Information Systems

A text filtering system monitors a stream of incoming documents, to identify those that match the interest profiles of its users. The user interests are registered at a server as continuous text search queries. The server constantly maintains for each query a ranked result list, comprising the recent documents (drawn from a sliding window) with the highest similarity to the query. Such a system underlies many text monitoring applications that need to cope with heavy document traffic, such as news and email monitoring. In this paper, we propose the first solution for processing continuous text queries efficiently. Our objective is …


Optimizing Service Systems Based On Application-Level Qos, Qianhui Liang, Xindong Wu, Hoong Chuin Lau Apr 2009

Optimizing Service Systems Based On Application-Level Qos, Qianhui Liang, Xindong Wu, Hoong Chuin Lau

Research Collection School Of Computing and Information Systems

Making software systems service-oriented is becoming the practice, and an increasingly large number of service systems play important roles in today's business and industry. Currently, not enough attention has been paid to the issue of optimization of service systems. In this paper, we argue that the key elements to be considered in optimizing service systems are robustness, system orientation, and being dynamic and transparent. We present our solution to optimizing service systems based on application-level QoS management. Our solution incorporates three capabilities, i.e., 1) the ability to cater to the varying rigidities on Web service QoS in distinct application domains …


A Social Relation Aware Routing Protocol For Mobile Ad Hoc Networks, Jisun An, Yangwoo Ko, Dongman Lee Mar 2009

A Social Relation Aware Routing Protocol For Mobile Ad Hoc Networks, Jisun An, Yangwoo Ko, Dongman Lee

Research Collection School Of Computing and Information Systems

In this paper, we propose a social relation aware routing protocol for mobile ad hoc networks, which is designed for content sharing mobile social applications. Since a content can be shared by a group of users who have similar interests, the similarity of users' interests is a good metric to predict who will consume which contents. Shared interests can be exploited in routing and replication of content request and reply to achieve enhanced efficacy in content sharing. Since routing determines which content will be forwarded by whom, a route selected based on similarity of interest increases the utilization of contents …


Server-Assisted Context-Dependent Pervasive Wellness Monitoring, Archan Misra, Ben Falchuk, Shoshana Loeb Mar 2009

Server-Assisted Context-Dependent Pervasive Wellness Monitoring, Archan Misra, Ben Falchuk, Shoshana Loeb

Research Collection School Of Computing and Information Systems

Recent research on remote health monitoring solutions has focused largely on developing context-dependent, streamprocessing capabilities on a personal mobile hub (typically, a cellphone) for energy-efficient transmission of data collected from a set of body-worn medical sensors. In this paper, we argue that commercial deployment of such pervasive wellness monitoring will require the extension of such ‘context dependency’ to the process of data collection (from the sensors to the mobile device) as well. In particular, the utilization of an individuals non-medical activity context, by the cellphone, in coordination with a backend server, is posited to be the key to supporting important …


Programmable Presence Virtualization For Next-Generation Context-Based Applications, Arup Acharya, Nilanjan Banerjee, Dipanjan Chakraborty, Koustuv Dasgupta, Archan Misra, Shachi Sharma, Xiping Wang, Charles P. Wright Mar 2009

Programmable Presence Virtualization For Next-Generation Context-Based Applications, Arup Acharya, Nilanjan Banerjee, Dipanjan Chakraborty, Koustuv Dasgupta, Archan Misra, Shachi Sharma, Xiping Wang, Charles P. Wright

Research Collection School Of Computing and Information Systems

Presence, broadly defined as an event publish-notification infrastructure for converged applications, has emerged as a key mechanism for collecting and disseminating context attributes for next-generation services in both enterprise and provider domains. Current presence-based solutions and products lack in the ability to a) support flexible user-defined queries over dynamic presence data and b) derive composite presence from multiple provider domains. Accordingly, current uses of context are limited to individual domains/organizations and do not provide a programmable mechanism for rapid creation of context-aware services. This paper describes a presence virtualization architecture, where a virtualized presence server receives customizable queries from multiple …


Visual Word Proximity And Linguistics For Semantic Video Indexing And Near-Duplicate Retrieval, Yu-Gang Jiang, Chong-Wah Ngo Mar 2009

Visual Word Proximity And Linguistics For Semantic Video Indexing And Near-Duplicate Retrieval, Yu-Gang Jiang, Chong-Wah Ngo

Research Collection School Of Computing and Information Systems

Bag-of-visual-words (BoW) has recently become a popular representation to describe video and image content. Most existing approaches, nevertheless, neglect inter-word relatedness and measure similarity by bin-to-bin comparison of visual words in histograms. In this paper, we explore the linguistic and ontological aspects of visual words for video analysis. Two approaches, soft-weighting and constraint-based earth mover’s distance (CEMD), are proposed to model different aspects of visual word linguistics and proximity. In soft-weighting, visual words are cleverly weighted such that the linguistic meaning of words is taken into account for bin-to-bin histogram comparison. In CEMD, a cross-bin matching algorithm is formulated such …


Continuous Visible Nearest Neighbour Queries, Yunjun Gao, Baihua Zheng, Wang-Chien Lee, Gencai Chen Mar 2009

Continuous Visible Nearest Neighbour Queries, Yunjun Gao, Baihua Zheng, Wang-Chien Lee, Gencai Chen

Research Collection School Of Computing and Information Systems

In this paper, we identify and solve a new type of spatial queries, called continuous visible nearest neighbor (CVNN) search. Given a data set P, an obstacle set O, and a query line segment q, a CVNN query returns a set of (p, R) tuples such that p ? P is the nearest neighbor (NN) to every point r along the interval R ? q as well as p is visible to r. Note that p may be NULL, meaning that all points in P are invisible to all points in R, due to the obstruction of some obstacles in …


Web Query Recommendation Via Sequential Query Prediction, Qi He, Daxin Jiang, Zhen Liao, Steven C. H. Hoi, Kuiyu Chang, Ee Peng Lim, Hang Li Mar 2009

Web Query Recommendation Via Sequential Query Prediction, Qi He, Daxin Jiang, Zhen Liao, Steven C. H. Hoi, Kuiyu Chang, Ee Peng Lim, Hang Li

Research Collection School Of Computing and Information Systems

Web query recommendation has long been considered a key feature of search engines. Building a good Web query recommendation system, however, is very difficult due to the fundamental challenge of predicting users' search intent, especially given the limited user context information. In this paper, we propose a novel "sequential query prediction" approach that tries to grasp a user's search intent based on his/her past query sequence and its resemblance to historical query sequence models mined from massive search engine logs. Different query sequence models were examined, including the naive variable length N-gram model, Variable Memory Markov (VMM) model, and our …


House Of Cards, M. Thulasidas Mar 2009

House Of Cards, M. Thulasidas

Research Collection School Of Computing and Information Systems

We are in dire straits - no doubt about it. Our banks and financial edifices are collapsing. Those left standing also look shaky. The financial industry as a whole is battling to survive. And, as its frontline warriors, we will bear the brunt of the blood- bath sure to ensue any minute now. A good opportunity to play solitaire?


Pat: Towards Flexible Verification Under Fairness, Jun Sun, Yang Liu, Jin Song Dong, Jun Pang Feb 2009

Pat: Towards Flexible Verification Under Fairness, Jun Sun, Yang Liu, Jin Song Dong, Jun Pang

Research Collection School Of Computing and Information Systems

Recent development on distributed systems has shown that a variety of fairness constraints (some of which are only recently defined) play vital roles in designing self-stabilizing population protocols. Current practice of system analysis is, however, deficient under fairness. In this work, we present PAT, a toolkit for flexible and efficient system analysis under fairness. A unified algorithm is proposed to model check systems with a variety of fairness effectively in two different settings. Empirical evaluation shows that PAT complements existing model checkers in terms of fairness. We report that previously unknown bugs have been revealed using PAT against systems functioning …


Bmq-Processor: A High-Performance Border Crossing Event Detection Framework For Large-Scale Monitoring Applications, Jinwon Lee, Seungwoo Kang, Youngki Lee, Sangjeong Lee, Junehwa Song Feb 2009

Bmq-Processor: A High-Performance Border Crossing Event Detection Framework For Large-Scale Monitoring Applications, Jinwon Lee, Seungwoo Kang, Youngki Lee, Sangjeong Lee, Junehwa Song

Research Collection School Of Computing and Information Systems

In this paper, we present BMQ-Processor, a high-performance Border-Crossing Event (BCE) detection framework for large-scale monitoring applications. We first characterize a new query semantics, namely, Border Monitoring Query (BMQ), which is useful for BCE detection in many monitoring applications. It monitors the values of data streams and reports them only when data streams cross the borders of its range. We then propose BMQ-Processor to efficiently handle a large number of BMQs over a high volume of data streams. BMQ-Processor efficiently processes BMQs in a shared and incremental manner. It develops and operates over a novel stateful query index, achieving a …


Scale-Rotation Invariant Pattern Entropy For Keypoint-Based Near-Duplicate Detection, Wan-Lei Zhao, Chong-Wah Ngo Feb 2009

Scale-Rotation Invariant Pattern Entropy For Keypoint-Based Near-Duplicate Detection, Wan-Lei Zhao, Chong-Wah Ngo

Research Collection School Of Computing and Information Systems

Near-duplicate (ND) detection appears as a timely issue recently, being regarded as a powerful tool for various emerging applications. In the Web 2.0 environment particularly, the identification of near-duplicates enables the tasks such as copyright enforcement, news topic tracking, image and video search. In this paper, we describe an algorithm, namely Scale-Rotation invariant Pattern Entropy (SR-PE), for the detection of near-duplicates in large-scale video corpus. SR-PE is a novel pattern evaluation technique capable of measuring the spatial regularity of matching patterns formed by local keypoints. More importantly, the coherency of patterns and the perception of visual similarity, under the scenario …


Real-Time Near-Duplicate Elimination For Web Video Search With Content And Context, Xiao Wu, Chong-Wah Ngo, Alexander G. Hauptmann Feb 2009

Real-Time Near-Duplicate Elimination For Web Video Search With Content And Context, Xiao Wu, Chong-Wah Ngo, Alexander G. Hauptmann

Research Collection School Of Computing and Information Systems

With the exponential growth of social media, there exist huge numbers of near-duplicate web videos, ranging from simple formatting to complex mixture of different editing effects. In addition to the abundant video content, the social web provides rich sets of context information associated with web videos, such as thumbnail image, time duration and so on. At the same time, the popularity of Web 2.0 demands for timely response to user queries. To balance the speed and accuracy aspects, in this paper, we combine the contextual information from time duration, number of views, and thumbnail images with the content analysis derived …


Stochastic Modeling Western Paintings For Effective Classification, Jialie Shen Feb 2009

Stochastic Modeling Western Paintings For Effective Classification, Jialie Shen

Research Collection School Of Computing and Information Systems

As one of the most important cultural heritages, classical western paintings have always played a special role in human live and been applied for many different purposes. While image classification is the subject of a plethora of related publications, relatively little attention has been paid to automatic categorization of western classical paintings which could be a key technique of modern digital library, museums and art galleries. This paper studies automatic classification on large western painting image collection. We propose a novel framework to support automatic classification on large western painting image collections. With this framework, multiple visual features can be …


Integrated Cognitive Architectures: A Survey, Hui-Qing Chong, Ah-Hwee Tan, Gee-Wah Ng Feb 2009

Integrated Cognitive Architectures: A Survey, Hui-Qing Chong, Ah-Hwee Tan, Gee-Wah Ng

Research Collection School Of Computing and Information Systems

This article aims to present an account of the state of the art research in the field of integrated cognitive architectures by providing a review of six cognitive architectures, namely Soar, ACT-R, ICARUS, BDI, the subsumption architecture and CLARION. We conduct a detailed functional comparison by looking at a wide range of cognitive components, including perception, memory, goal representation, planning, problem solving, reasoning, learning, and relevance to neurobiology. In addition, we study the range of benchmarks and applications that these architectures have been applied to. Although no single cognitive architecture has provided a full solution with the level of human …


Learning Image‐Text Associations, Tao Jiang, Ah-Hwee Tan Feb 2009

Learning Image‐Text Associations, Tao Jiang, Ah-Hwee Tan

Research Collection School Of Computing and Information Systems

Web information fusion can be defined as the problem of collating and tracking information related to specific topics on the World Wide Web. Whereas most existing work on Web information fusion has focused on text-based multidocument summarization, this paper concerns the topic of image and text association, a cornerstone of cross-media Web information fusion. Specifically, we present two learning methods for discovering the underlying associations between images and texts based on small training data sets. The first method based on vague transformation measures the information similarity between the visual features and the textual features through a set of predefined domain-specific …


Chaos And Uncertainty, M. Thulasidas Jan 2009

Chaos And Uncertainty, M. Thulasidas

Research Collection School Of Computing and Information Systems

The end of 2008 in the finance industry can be summarized in two words – chaos and uncertainty. The subprime crisis, where everybody lost; the dizzying commodity price movements; the pink slip syndrome; the spectacular bank busts; and the gargantuan bail-outs all vouch for it.


Modelling Situation Awareness For Context‐Aware Decision Support, Yu-Hong Feng, Teck-Hou Teng, Ah-Hwee Tan Jan 2009

Modelling Situation Awareness For Context‐Aware Decision Support, Yu-Hong Feng, Teck-Hou Teng, Ah-Hwee Tan

Research Collection School Of Computing and Information Systems

Situation awareness modelling is popularly used in the command and control domain for situation assessment and decision support. However, situation models in real-world applications are typically complex and not easy to use. This paper presents a Context-aware Decision Support (CaDS) system, which consists of a situation model for shared situation awareness modelling and a group of entity agents, one for each individual user, for focused and customized decision support. By incorporating a rule-based inference engine, the entity agents provide functions including event classification, action recommendation, and proactive decision making. The implementation and the performance of the proposed system are demonstrated …


When Is It Beneficial For A Firm To Pursue A Unified Procurement Strategy For Enterprise Software Solutions?, Robert J. Kauffman, Juliana Y. Tsai Jan 2009

When Is It Beneficial For A Firm To Pursue A Unified Procurement Strategy For Enterprise Software Solutions?, Robert J. Kauffman, Juliana Y. Tsai

Research Collection School Of Computing and Information Systems

The underlying structure of the enterprise software marketplace during the past ten years suggests that the arrangements that firms make with respect to the acquisition of such software capabilities will become increasingly concentrated. This article explores the multiple theoretical rationales and business cases for the move to a unified procurement strategy for enterprise software, reflecting some differences in terms of what might be expected from the predictions of the well known move-to-the-middle hypothesis. Our central argument is that a "move-to-the-middle" with more than just a single vendor is the likely outcome in unconsolidated industry markets. In industries experiencing consolidation, firms …


A Semiotic Analysis Of Unified Modeling Language Graphical Notations, Keng Siau, Yuhong Tian Jan 2009

A Semiotic Analysis Of Unified Modeling Language Graphical Notations, Keng Siau, Yuhong Tian

Research Collection School Of Computing and Information Systems

Unified modeling language (UML) is the standard modeling language for object-oriented system development. Despite its status as a standard, UML has a fuzzy formal specification and a weak theoretical foundation. Semiotics, the study of signs, provides a good theoretical foundation for UML research because graphical notations (or visual signs) of UML are subjected to the principles of signs. In our research, we use semiotics to study the effectiveness of graphical notations in UML. We hypothesized that the use of iconic signs as UML graphical notations leads to representation that is more accurately interpreted and that arouses fewer connotations than the …