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31
Optimal Prefetching via Data Compression
, 1995
"... Caching and prefetching are important mechanisms for speeding up access time to data on secondary storage. Recent work in competitive online algorithms has uncovered several promising new algorithms for caching. In this paper we apply a form of the competitive philosophy for the first time to the pr ..."
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Cited by 245 (10 self)
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Caching and prefetching are important mechanisms for speeding up access time to data on secondary storage. Recent work in competitive online algorithms has uncovered several promising new algorithms for caching. In this paper we apply a form of the competitive philosophy for the first time to the problem of prefetching to develop an optimal universal prefetcher in terms of fault ratio, with particular applications to largescale databases and hypertext systems. Our prediction algorithms for prefetching are novel in that they are based on data compression techniques that are both theoretically optimal and good in practice. Intuitively, in order to compress data effectively, you have to be able to predict future data well, and thus good data compressors should be able to predict well for purposes of prefetching. We show for powerful models such as Markov sources and nth order Markov sources that the page fault rates incurred by our prefetching algorithms are optimal in the limit for almost all sequences of page requests.
The Power of Amnesia: Learning Probabilistic Automata with Variable Memory Length
 Machine Learning
, 1996
"... . We propose and analyze a distribution learning algorithm for variable memory length Markov processes. These processes can be described by a subclass of probabilistic finite automata which we name Probabilistic Suffix Automata (PSA). Though hardness results are known for learning distributions gene ..."
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Cited by 187 (17 self)
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. We propose and analyze a distribution learning algorithm for variable memory length Markov processes. These processes can be described by a subclass of probabilistic finite automata which we name Probabilistic Suffix Automata (PSA). Though hardness results are known for learning distributions generated by general probabilistic automata, we prove that the algorithm we present can efficiently learn distributions generated by PSAs. In particular, we show that for any target PSA, the KLdivergence between the distribution generated by the target and the distribution generated by the hypothesis the learning algorithm outputs, can be made small with high confidence in polynomial time and sample complexity. The learning algorithm is motivated by applications in humanmachine interaction. Here we present two applications of the algorithm. In the first one we apply the algorithm in order to construct a model of the English language, and use this model to correct corrupted text. In the second ...
Identifying hierarchical structure in sequences: A lineartime algorithm
, 1997
"... SEQUITUR is an algorithm that infers a hierarchical structure from a sequence of discrete symbols by replacing repeated phrases with a grammatical rule that generates the phrase, and continuing this process recursively. The result is a hierarchical representation of the original sequence, which offe ..."
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Cited by 168 (3 self)
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SEQUITUR is an algorithm that infers a hierarchical structure from a sequence of discrete symbols by replacing repeated phrases with a grammatical rule that generates the phrase, and continuing this process recursively. The result is a hierarchical representation of the original sequence, which offers insights into its lexical structure. The algorithm is driven by two constraints that reduce the size of the grammar, and produce structure as a byproduct. SEQUITUR breaks new ground by operating incrementally. Moreover, the method’s simple structure permits a proof that it operates in space and time that is linear in the size of the input. Our implementation can process 50,000 symbols per second and has been applied to an extensive range of real world sequences. 1.
Software Agents: Completing Patterns and Constructing User Interfaces
 Journal of Artificial Intelligence Research
, 1993
"... To support the goal of allowing users to record and retrieve information, this paper describes an interactive notetaking system for penbased computers with two distinctive features. First, it actively predicts what the user is going to write. Second, it automatically constructs a custom, buttonbo ..."
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Cited by 56 (2 self)
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To support the goal of allowing users to record and retrieve information, this paper describes an interactive notetaking system for penbased computers with two distinctive features. First, it actively predicts what the user is going to write. Second, it automatically constructs a custom, buttonbox user interface on request. The system is an example of a learningapprentice softwareagent. A machine learning component characterizes the syntax and semantics of the user's information. A performance system uses this learned information to generate completion strings and construct a user interface. 1. Introduction and Motivation People like to record information for later consultation. For many, the media of choice is paper. It is easy to use, inexpensive, and durable. To its disadvantage, paper records do not scale well. As the amount of information grows, retrieval becomes inefficient, physical storage becomes excessive, and duplication and distribution become expensive. Digital medi...
Machine Learning Techniques for the Computer Security Domain of Anomaly Detection
, 2000
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Cited by 37 (1 self)
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Predicting the Future of Discrete Sequences From Fractal Representations of the Past
, 2001
"... We propose a novel approach for building nite memory predictive models similar in spirit to variable memory length Markov models (VLMMs). The models are constructed by rst transforming the nblock structure of the training sequence into a geometric structure of points in a unit hypercube, such ..."
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Cited by 29 (10 self)
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We propose a novel approach for building nite memory predictive models similar in spirit to variable memory length Markov models (VLMMs). The models are constructed by rst transforming the nblock structure of the training sequence into a geometric structure of points in a unit hypercube, such that the longer is the common sux shared by any two nblocks, the closer lie their point representations.
Optimal Prediction for Prefetching in the Worst Case
, 1998
"... Response time delays caused by I/O are a major problem in many systems and database applications. Prefetching and cache replacement methods are attracting renewed attention because of their success in avoiding costly I/Os. Prefetching can be looked upon as a type of online sequential prediction, whe ..."
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Cited by 28 (7 self)
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Response time delays caused by I/O are a major problem in many systems and database applications. Prefetching and cache replacement methods are attracting renewed attention because of their success in avoiding costly I/Os. Prefetching can be looked upon as a type of online sequential prediction, where the predictions must be accurate as well as made in a computationally efficient way. Unlike other online problems, prefetching cannot admit a competitive analysis, since the optimal offline prefetcher incurs no cost when it knows the future page requests. Previous analytical work on prefetching [J. Assoc. Comput. Mach., 143 (1996), pp. 771–793] consisted of modeling the user as a probabilistic Markov source. In this paper, we look at the much stronger form of worstcase analysis and derive a randomized algorithm for pure prefetching. We compare our algorithm for every page request sequence with the important class of finite state prefetchers, making no assumptions as to how the sequence of page requests is generated. We prove analytically that the fault rate of our online prefetching algorithm converges almost surely for every page request sequence to the fault rate of the optimal finite state prefetcher for the sequence. This analysis model can be looked upon as a generalization of the competitive framework, in that it compares an online algorithm in a worstcase manner over all sequences with a powerful yet nonclairvoyant opponent. We simultaneously achieve the computational goal of implementing our prefetcher in optimal constant expected time per prefetched page using the optimal dynamic discrete random variate generator of Matias, Vitter, and Ni [Proc. 4th Annual SIAM/ACM
Recurrent Neural Networks With Small Weights Implement Definite Memory Machines
 NEURAL COMPUTATION
, 2003
"... Recent experimental studies indicate that recurrent neural networks initialized with `small' weights are inherently biased towards definite memory machines (Tino, Cernansky, Benuskova, 2002a; Tino, Cernansky, Benuskova, 2002b). This paper establishes a theoretical counterpart: transition ..."
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Cited by 23 (6 self)
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Recent experimental studies indicate that recurrent neural networks initialized with `small' weights are inherently biased towards definite memory machines (Tino, Cernansky, Benuskova, 2002a; Tino, Cernansky, Benuskova, 2002b). This paper establishes a theoretical counterpart: transition function of recurrent network with small weights and `squashing ' activation function is a contraction. We prove that recurrent networks with contractive transition function can be approximated arbitrarily well on input sequences of unbounded length by a definite mem
Detecting Concept Drift in Financial Time Series Prediction using Symbolic Machine Learning
, 1995
"... This paper investigates the use of strategies to enhance an existing machine learning tool, C4.5, to deal with concept drift and nondeterminism in a time series domain. Temporal prediction is a difficult problem faced in most human endeavours. While many specialised time series prediction technique ..."
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Cited by 10 (5 self)
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This paper investigates the use of strategies to enhance an existing machine learning tool, C4.5, to deal with concept drift and nondeterminism in a time series domain. Temporal prediction is a difficult problem faced in most human endeavours. While many specialised time series prediction techniques have been developed, these techniques have limitations. Most are restricted to modeling whole series rather than extracting predictive features and are difficult for domain experts to understand. Symbolic machine learning promises to address these limitations. Symbolic machine learning has been very successful on a broad range of complex problems. To date, few attempts have been made to apply symbolic machine learning directly to temporal prediction. This has resulted in systems that cannot explicitly represent temporally ordered examples or handle changing target concepts. Financial prediction is a challenging target domain, which is temporally ordered, has target concepts that change ove...