16010600
Properties of Forward Pruning in Game-Tree Search
Forward pruning, or selectively searching a subset of moves, is now commonly used in game-playing programs to reduce the number of nodes searched with manageable risk. Forward pruning techniques should consider how pruning errors in a game-tree search propagate to the root to minimize the risk of making errors. In this paper, we explore forward pruning using theoretical analyses and Monte Carlo simulations and report on two findings. Firstly, we find that pruning errors propagate differently depending on the player to move, and show that pruning errors on the opponent's moves are potentially more serious than pruning errors on the player's own moves. This suggests that pruning on the player's own move can be performed more aggressively compared to pruning on the opponent's move. Secondly, we examine the ability of the minimax search to filter away pruning errors and give bounds on the rate of error propagation to the root. We find that if the rate of pruning error is kept constant, the growth of errors with the depth of the tree dominates the filtering effect, therefore suggesting that pruning should be done more aggressively near the root and less aggressively near the leaves.
2748729
Partially Supervised Classification of Text Documents
We investigate the following problem: Given a set of documents of a particular topic or class P , and a large set M of mixed documents that contains documents from class P and other types of documents, identify the documents from class P in M . The key feature of this problem is that there is no labeled nonP document, which makes traditional machine learning techniques inapplicable, as they all need labeled documents of both classes. We call this problem partially supervised classification. In this paper, we show that this problem can be posed as a constrained optimization problem and that under appropriate conditions, solutions to the constrained optimization problem will give good solutions to the partially supervised classification problem. We present a novel technique to solve the problem and demonstrate the effectiveness of the technique through extensive experimentation.
12294439
Learning to Separate Text Content and Style for Classification
Many text documents naturally have two kinds of labels. For example, we may label web pages from universities according to their categories, such as “student” or “faculty”, or according the source universities, such as “Cornell” or “Texas”. We call one kind of labels the content and the other kind the style. Given a set of documents, each with both content and style labels, we seek to effectively learn to classify a set of documents in a new style with no content labels into its content classes. Assuming that every document is generated using words drawn from a mixture of two multinomial component models, one content model and one style model, we propose a method named Cartesian EM that constructs content models and style models through Expectation Maximization and performs classification of the unknown content classes transductively. Our experiments on real-world datasets show the proposed method to be effective for style independent text content classification.
9023584
Text classification with kernels on the multinomial manifold
Support Vector Machines (SVMs) have been very successful in text classification. However, the intrinsic geometric structure of text data has been ignored by standard kernels commonly used in SVMs. It is natural to assume that the documents are on the multinomial manifold, which is the simplex of multinomial models furnished with the Riemannian structure induced by the Fisher information metric. We prove that the Negative Geodesic Distance (NGD) on the multinomial manifold is conditionally positive definite (cpd), thus can be used as a kernel in SVMs. Experiments show the NGD kernel on the multinomial manifold to be effective for text classification, significantly outperforming standard kernels on the ambient Euclidean space.
37770250
A Theoretical Analysis of Query Selection for Collaborative Filtering
We consider the problem of determining which of a set of experts has tastes most similar to a given user by asking the user questions about his likes and dislikes. We describe a simple and fast algorithm for a theoretical model of this problem with a provable approximation guarantee, and prove that solving the problem exactly is NP-Hard.
1176859
RankCut - A Domain Independent Forward Pruning Method for Games
Forward pruning, also known as selective search, is now employed in many strong game-playing programs. In this paper, we introduce RankCut – a domain independent forward pruning technique which makes use of move ordering, and prunes once no better move is likely to be available. Since gameplaying programs already perform move ordering to improve the performance of αβ search, this information is available at no extra cost. As RankCut uses additional information untapped by current forward pruning techniques, RankCut is a complementary forward pruning method that can be used with existing methods, and is able to achieve improvements even when conventional pruning techniques are simultaneously employed. We implemented RankCut in a modern open-source chess program, CRAFTY. RankCut reduces the game-tree size by approximately 10%-40% for search depths 8-12 while retaining tactical reliability, when implemented alongside CRAFTY’s existing forward pruning techniques.
22742444
Distributed scalable location data management system based on the GALIS architecture
A challenging task in the LBS system engineering is to implement a highly scalable system architecture which can manage moderate-size configurations handling thousands of moving items as well as upper-end configurations handling millions of moving items. The architecture named the GALIS is a cluster-based distributed computing system architecture that consists of multiple data processors, each dedicated to keeping records relevant to a different geographical zone and a different time zone. In this paper, we explain a prototype location data management system structuring major components of GALIS by employing the TMO programming scheme, including the execution engine middleware developed to support real-time distributed object programming and real-time distributed computing system design. We present how to generate realistic location sensing reports and how to process such location reports and location-related queries. Some experimental results showing performance factors regarding distributed query processing are also explained.
195713214
Using Signature Techniques for Information Filtering in Wireless and Mobile Environments
This paper discusses the issue of power conservation on mobile clients, e.g., palmtop, in wireless and mobile environments. It suggests that techniques using signatures are suitable for realtime information filtering on mobile clients. Three signature-based approaches, namely simple signature, integrated signature and multi-level signature schemes, are presented. The cost models for the access time and tune-in time of these three approaches are developed. We show that the multi-level signature method is in general better than the other two methods.
34349141
Proactive Intrusion Detection and Distributed Denial of Service Attacks—A Case Study in Security Management
Little or no integration exists today between Intrusion Detection Systems (IDSs) and SNMP-based Network Management Systems (NMSs), in spite of the extensive monitoring and alarming capabilities offered by commercial NMSs. This difficulty is mainly associated with the distinct data sources used by the two systems: packet traffic and audit records for IDSs and SNMP MIB variables for NMSs. In this paper we propose and evaluate a methodology for utilizing NMSs for the early detection of Distributed Denial of Service attacks (DDoS). A principled approach is described for discovering precursors to DDoS attacks in databases formed by MIB variables recorded from multiple domains in networked information systems. The approach is rooted in time series quantization, and in the application of the Granger Causality Test of classical statistics for selecting variables that are likely to contain precursors. A methodology is proposed for discovering precursor rules from databases containing time series related to different regimes of a system. These precursor rules relate precursor events extracted from input time series with phenomenon events extracted from output time series. Using MIB datasets collected from real experiments involving Distributed Denial of Service Attacks, it is shown that precursor rules relating activities at attacking machines with traffic floods at target machines can be extracted by the methodology. The technology has extensive applications for security management: it enables security analysts to better understand the evolution of complex computer attacks, it can be used to trigger alarms indicating that an attack is imminent, or it can be used to reduce the false alarm rates of conventional IDSs.
15482443
Applying data mining to intrusion detection: the quest for automation, efficiency, and credibility
Intrusion detection is an essential component of the layered computer security mechanisms. It requires accurate and efficient models for analyzing a large amount of system and network audit data. This paper is an overview of our research in applying data mining techniques to build intrusion detection models. We describe a framework for mining patterns from system and network audit data, and constructing features according to analysis of intrusion patterns. We discuss approaches for improving the run-time efficiency as well as the credibility of detection models. We report the ideas, algorithms, and prototype systems we have developed, and discuss open research problems.
7965599
q-gram matching using tree models
q-gram matching is used for approximate substring matching problems in a wide range of application areas, including intrusion detection. In this paper, we present a tree-based model to perform fast linear time q-gram matching. All q-grams present in the text are stored in a tree structure similar to trie. We use a tree redundancy pruning algorithm to reduce the size of the tree without losing any information. We also use suffix links for fast q-gram search during query matching. We compare our work with the Rabin-Karp-based hash-table technique, commonly used for multiple q-gram search. We present results of experiments on system call sequence data used for intrusion detection.