The small world phenomenon formalizes the anecdotal notion that "you are only ever six de- g... more The small world phenomenon formalizes the anecdotal notion that "you are only ever six de- grees of separation away from anybody else on the planet." Almost everyone is familiar with the experience of running into a complete stranger at a party or in some public arena and, after a short conversation, discovering to have some unexpected mutual acquaintanceship. "Well, it's a small-world!" one would exclaim. ... The small-world phenomenon is a generalized version of this experience, the claim being that even when two people do not have much in ...
The paper describes a general framework that can be used to solve an optimization problem when an... more The paper describes a general framework that can be used to solve an optimization problem when an efficient algorithm for the decision version of the problem exists. Some applications of the proposed technique are investigated. The framework yields simpler solutions that match the known time complexity lower bounds for some geometric problems and, in some cases, it improves them by logarithmic factors.
Suppose we have a set of n axis-aligned rectangular boxes in d-space,{B 1, B 2,…, B n}, where eac... more Suppose we have a set of n axis-aligned rectangular boxes in d-space,{B 1, B 2,…, B n}, where each box B i is active (or present) with an independent probability p i. We wish to compute the expected volume occupied by the union of all the active boxes. Our main result is a data structure for maintaining the expected volume over a dynamic family of such probabilistic boxes at an amortized cost of O (n (d− 1)/2 logn) time per insert or delete.
Abstract In global grid computing, ie, wide area network (WAN) grid computing. Grid network servi... more Abstract In global grid computing, ie, wide area network (WAN) grid computing. Grid network services allow grid users or the programming environment to monitor the status of network resources and to reallocate them. Specifically, the network information and monitoring service (NIMS) provides up to date information on the grid network status. In this study two implementations of a specific NIMS component, ie, the topology discovery service (TDS), are presented.
Abstract We investigate the complexity of shortest paths in time-dependent graphs, in which the c... more Abstract We investigate the complexity of shortest paths in time-dependent graphs, in which the costs of edges vary as a function of time, and as a result the shortest path between two nodes s and d can change over time. Our main result is that when the edge cost functions are (polynomial-size) piecewise linear, the shortest path from s to d can change n θ (log n) times, settling a several-year-old conjecture of Dean [Technical Reports, 1999, 2004].
Abstract: Monitoring the performance of large shared computing systems such as the cloud computin... more Abstract: Monitoring the performance of large shared computing systems such as the cloud computing infrastructure raises many challenging algorithmic problems. One common problem is to track users with the largest deviation from the norm (outliers), for some measure of performance.
Abstract The dynamic joint optimization of both computational and network resources has the poten... more Abstract The dynamic joint optimization of both computational and network resources has the potential of guaranteeing optimal performance Io geographically distributed grid applications. A grid network information and monitoring service (NIMS) has been recently proposed to complement computational resource status information with network resource status information.
Abstract We report on a simple encoding format called wzip for decompressing block-sorting transf... more Abstract We report on a simple encoding format called wzip for decompressing block-sorting transforms, such as the Burrows-Wheeler transform (BWT). Our compressor uses the simple notions of gamma encoding and RLE, organized with a wavelet tree, to achieve a slightly better compression ratio than bzip2 in less time. In fact, our compression/decompression time is dependent on H h, the hth order empirical entropy. This relationship of performance to the compressibility of data is a key new idea among compression algorithms.
Abstract In this paper, we propose an approach to complexity reduction of Mamdani-type fuzzy rule... more Abstract In this paper, we propose an approach to complexity reduction of Mamdani-type fuzzy rule-based systems (FRBSs) based on removing logical redundancies. We first generate an FRBS from data by applying a simplified version of the well-known Wang and Mendel method. Then, we represent the FRBS as a multi-valued logic relation. Finally, we apply MVSIS, a tool for circuit minimization and simulation, to minimize the relation and consequently to reduce complexity of the associated FRBS.
Abstract We report on a new experimental analysis of high-order entropy-compressed suffix arrays,... more Abstract We report on a new experimental analysis of high-order entropy-compressed suffix arrays, which retains the theoretical performance of previous work and represents an improvement in practice. Our experiments indicate that the resulting text index offers state-of-the-art compression. In particular, we require roughly 20% of the original text size---without requiring a separate instance of the text.
The increase in bandwidth over processing power has made stateful intrusion detection for high-sp... more The increase in bandwidth over processing power has made stateful intrusion detection for high-speed networks more difficult, and, in certain cases, impossible. The problem of real-time stateful intrusion detection in high-speed networks cannot easily be solved by optimizing the packet matching algorithm utilized by a centralized process or by using custom-developed hardware. Instead, there is a need for a parallel approach that is able to decompose the problem into subproblems of manageable size.
Abstract In this paper, we present an abstract framework for online approximation of time-series ... more Abstract In this paper, we present an abstract framework for online approximation of time-series data that yields a unified set of algorithms for several popular models: data streams, amnesic approximation, and out-of-order stream approximation. Our framework essentially develops a popular greedy method of bucket-merging into a more generic form, for which we can prove space-quality approximation bounds.
Abstract Pixelization is a technique to make parts of an image impossible to discern by the human... more Abstract Pixelization is a technique to make parts of an image impossible to discern by the human eye by artificially decreasing the image resolution. Pixelization, as other forms of image censorship, is effective at hiding parts of an image that might be offensive to the viewer. However, pixelization is also often used also to achieve anonymity, for example to make the features of a person's face unrecognizable or the defining characteristics of cars and building unidentifiable.
Abstract The need to identify correlated traffic bursts at various, and especially fine-grain, ti... more Abstract The need to identify correlated traffic bursts at various, and especially fine-grain, time scales has become pressing in modern data centers. The combination of Gigabit link speeds and small switch buffers have led to “microbursts”, which cause packet drops and large increases in latency. Our paper describes the design and implementation of an efficient and flexible end-host bandwidth measurement tool that can identify such bursts in addition to providing a number of other features.
Today Grid Computing is ubiquitous. As of June 2005 searching those 2 words on Google would retur... more Today Grid Computing is ubiquitous. As of June 2005 searching those 2 words on Google would return more than 13 millions results and just the first ten results show how some of the largest technology companies in the world, like IBM, Intel, Sun Microsystems and HP have decided to invest in their own Grid Computing project.
Abstract The increase in bandwidth over processing power has made stateful intrusion detection fo... more Abstract The increase in bandwidth over processing power has made stateful intrusion detection for high-speed networks more difficult, and, in certain cases, impossible. The problem of realtime stateful intrusion detection in high-speed networks cannot be solved by optimizing the packet matching algorithm used by a centralized process or by using custom-developed hardware. Instead, there is a need for a parallel approach that is able to decompose the problem into subproblems of manageable size.
Abstract. Web search is extensively adopted for accessing information on the web, and recent deve... more Abstract. Web search is extensively adopted for accessing information on the web, and recent development in personalized search, social bookmarking and folksonomy systems has tremendously eased the user's path towards the desired information. In this paper, we discuss TC-SocialRank, a novel link-based algorithm which extends state-of-the-art algorithms for folksonomy systems.
The small world phenomenon formalizes the anecdotal notion that "you are only ever six de- g... more The small world phenomenon formalizes the anecdotal notion that "you are only ever six de- grees of separation away from anybody else on the planet." Almost everyone is familiar with the experience of running into a complete stranger at a party or in some public arena and, after a short conversation, discovering to have some unexpected mutual acquaintanceship. "Well, it's a small-world!" one would exclaim. ... The small-world phenomenon is a generalized version of this experience, the claim being that even when two people do not have much in ...
The paper describes a general framework that can be used to solve an optimization problem when an... more The paper describes a general framework that can be used to solve an optimization problem when an efficient algorithm for the decision version of the problem exists. Some applications of the proposed technique are investigated. The framework yields simpler solutions that match the known time complexity lower bounds for some geometric problems and, in some cases, it improves them by logarithmic factors.
Suppose we have a set of n axis-aligned rectangular boxes in d-space,{B 1, B 2,…, B n}, where eac... more Suppose we have a set of n axis-aligned rectangular boxes in d-space,{B 1, B 2,…, B n}, where each box B i is active (or present) with an independent probability p i. We wish to compute the expected volume occupied by the union of all the active boxes. Our main result is a data structure for maintaining the expected volume over a dynamic family of such probabilistic boxes at an amortized cost of O (n (d− 1)/2 logn) time per insert or delete.
Abstract In global grid computing, ie, wide area network (WAN) grid computing. Grid network servi... more Abstract In global grid computing, ie, wide area network (WAN) grid computing. Grid network services allow grid users or the programming environment to monitor the status of network resources and to reallocate them. Specifically, the network information and monitoring service (NIMS) provides up to date information on the grid network status. In this study two implementations of a specific NIMS component, ie, the topology discovery service (TDS), are presented.
Abstract We investigate the complexity of shortest paths in time-dependent graphs, in which the c... more Abstract We investigate the complexity of shortest paths in time-dependent graphs, in which the costs of edges vary as a function of time, and as a result the shortest path between two nodes s and d can change over time. Our main result is that when the edge cost functions are (polynomial-size) piecewise linear, the shortest path from s to d can change n θ (log n) times, settling a several-year-old conjecture of Dean [Technical Reports, 1999, 2004].
Abstract: Monitoring the performance of large shared computing systems such as the cloud computin... more Abstract: Monitoring the performance of large shared computing systems such as the cloud computing infrastructure raises many challenging algorithmic problems. One common problem is to track users with the largest deviation from the norm (outliers), for some measure of performance.
Abstract The dynamic joint optimization of both computational and network resources has the poten... more Abstract The dynamic joint optimization of both computational and network resources has the potential of guaranteeing optimal performance Io geographically distributed grid applications. A grid network information and monitoring service (NIMS) has been recently proposed to complement computational resource status information with network resource status information.
Abstract We report on a simple encoding format called wzip for decompressing block-sorting transf... more Abstract We report on a simple encoding format called wzip for decompressing block-sorting transforms, such as the Burrows-Wheeler transform (BWT). Our compressor uses the simple notions of gamma encoding and RLE, organized with a wavelet tree, to achieve a slightly better compression ratio than bzip2 in less time. In fact, our compression/decompression time is dependent on H h, the hth order empirical entropy. This relationship of performance to the compressibility of data is a key new idea among compression algorithms.
Abstract In this paper, we propose an approach to complexity reduction of Mamdani-type fuzzy rule... more Abstract In this paper, we propose an approach to complexity reduction of Mamdani-type fuzzy rule-based systems (FRBSs) based on removing logical redundancies. We first generate an FRBS from data by applying a simplified version of the well-known Wang and Mendel method. Then, we represent the FRBS as a multi-valued logic relation. Finally, we apply MVSIS, a tool for circuit minimization and simulation, to minimize the relation and consequently to reduce complexity of the associated FRBS.
Abstract We report on a new experimental analysis of high-order entropy-compressed suffix arrays,... more Abstract We report on a new experimental analysis of high-order entropy-compressed suffix arrays, which retains the theoretical performance of previous work and represents an improvement in practice. Our experiments indicate that the resulting text index offers state-of-the-art compression. In particular, we require roughly 20% of the original text size---without requiring a separate instance of the text.
The increase in bandwidth over processing power has made stateful intrusion detection for high-sp... more The increase in bandwidth over processing power has made stateful intrusion detection for high-speed networks more difficult, and, in certain cases, impossible. The problem of real-time stateful intrusion detection in high-speed networks cannot easily be solved by optimizing the packet matching algorithm utilized by a centralized process or by using custom-developed hardware. Instead, there is a need for a parallel approach that is able to decompose the problem into subproblems of manageable size.
Abstract In this paper, we present an abstract framework for online approximation of time-series ... more Abstract In this paper, we present an abstract framework for online approximation of time-series data that yields a unified set of algorithms for several popular models: data streams, amnesic approximation, and out-of-order stream approximation. Our framework essentially develops a popular greedy method of bucket-merging into a more generic form, for which we can prove space-quality approximation bounds.
Abstract Pixelization is a technique to make parts of an image impossible to discern by the human... more Abstract Pixelization is a technique to make parts of an image impossible to discern by the human eye by artificially decreasing the image resolution. Pixelization, as other forms of image censorship, is effective at hiding parts of an image that might be offensive to the viewer. However, pixelization is also often used also to achieve anonymity, for example to make the features of a person's face unrecognizable or the defining characteristics of cars and building unidentifiable.
Abstract The need to identify correlated traffic bursts at various, and especially fine-grain, ti... more Abstract The need to identify correlated traffic bursts at various, and especially fine-grain, time scales has become pressing in modern data centers. The combination of Gigabit link speeds and small switch buffers have led to “microbursts”, which cause packet drops and large increases in latency. Our paper describes the design and implementation of an efficient and flexible end-host bandwidth measurement tool that can identify such bursts in addition to providing a number of other features.
Today Grid Computing is ubiquitous. As of June 2005 searching those 2 words on Google would retur... more Today Grid Computing is ubiquitous. As of June 2005 searching those 2 words on Google would return more than 13 millions results and just the first ten results show how some of the largest technology companies in the world, like IBM, Intel, Sun Microsystems and HP have decided to invest in their own Grid Computing project.
Abstract The increase in bandwidth over processing power has made stateful intrusion detection fo... more Abstract The increase in bandwidth over processing power has made stateful intrusion detection for high-speed networks more difficult, and, in certain cases, impossible. The problem of realtime stateful intrusion detection in high-speed networks cannot be solved by optimizing the packet matching algorithm used by a centralized process or by using custom-developed hardware. Instead, there is a need for a parallel approach that is able to decompose the problem into subproblems of manageable size.
Abstract. Web search is extensively adopted for accessing information on the web, and recent deve... more Abstract. Web search is extensively adopted for accessing information on the web, and recent development in personalized search, social bookmarking and folksonomy systems has tremendously eased the user's path towards the desired information. In this paper, we discuss TC-SocialRank, a novel link-based algorithm which extends state-of-the-art algorithms for folksonomy systems.
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