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15
A Linear Programming Formulation for Global Inference in Natural Language Tasks
 In Proceedings of CoNLL2004
, 2004
"... The typical processing paradigm in natural language processing is the "pipeline" approach, where learners are being used at one level, their outcomes are being used as features for a second level of predictions and so one. In addition to accumulating errors, it is clear that the sequential ..."
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Cited by 116 (32 self)
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The typical processing paradigm in natural language processing is the "pipeline" approach, where learners are being used at one level, their outcomes are being used as features for a second level of predictions and so one. In addition to accumulating errors, it is clear that the sequential processing is a crude approximation to a process in which interactions occur across levels and down stream decisions often interact with previous decisions. This work develops a general...
Optimal scheduling of peertopeer file dissemination
 J. Scheduling
, 2006
"... Peertopeer (P2P) overlay networks such as BitTorrent and Avalanche are increasingly used for disseminating potentially large files from a server to many end users via the Internet. The key idea is to divide the file into many equallysized parts and then let users download each part (or, for netwo ..."
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Cited by 33 (1 self)
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Peertopeer (P2P) overlay networks such as BitTorrent and Avalanche are increasingly used for disseminating potentially large files from a server to many end users via the Internet. The key idea is to divide the file into many equallysized parts and then let users download each part (or, for network coding based systems such as Avalanche, linear combinations of the parts) either from the server or from another user who has already downloaded it. However, their performance evaluation has typically been limited to comparing one system relative to another and typically been realized by means of simulation and measurements. In contrast, we provide an analytic performance analysis that is based on a new uplinksharing version of the wellknown broadcasting problem. Assuming equal upload capacities, we show that the minimal time to disseminate the file is the same as for the simultaneous send/receive version of the broadcasting problem. For general upload capacities, we provide a mixed integer linear program (MILP) solution and a complementary fluid limit solution. We thus provide a lower bound which can be used as a performance benchmark for any P2P file dissemination system. We also investigate the performance of a decentralized strategy, providing evidence that the performance of necessarily decentralized P2P file dissemination systems should be close to this bound and therefore that it is useful in practice. 1
Efficient file dissemination using peertopeer technology
, 2004
"... We consider a problem which is partially motivated by the BitTorrent protocol. Suppose that a large file is initially available only at some server and we desire to disseminate it amongst N end users in the least possible time. We suppose that the file is divided in M parts of equal size and that an ..."
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Cited by 16 (1 self)
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We consider a problem which is partially motivated by the BitTorrent protocol. Suppose that a large file is initially available only at some server and we desire to disseminate it amongst N end users in the least possible time. We suppose that the file is divided in M parts of equal size and that an end user may download a part from either the server or one of the peers who has previously downloaded it. Given constraints on the rates at which the server and peers can upload to one another, we seek a strategy that minimizes the time until all peers have downloaded the entire file. Assuming that there is a centralized controller who does the scheduling of the uploads, we show how to solve this problem by solving a finite number of linear programs. Making connections with the socalled ‘broadcasting problem’, we provide a complete solution of this problem when the capacities are all equal. We also carry out simulations to assess the performance of a natural randomized algorithm that operates under distributed control. We compare the performance of this algorithm in two different information scenarios with what can be achieved by centralized control.
NearOptimal Loop Tiling by means of Cache Miss Equations and Genetic Algorithms
, 2001
"... The effectiveness of the memory hierarchy is critical for the performance of current processors. The performance of the memory hierarchy can be improved by means of program transformations such as loop tiling, which is a code transformation targeted to reduce capacity misses. This paper presents a n ..."
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Cited by 6 (2 self)
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The effectiveness of the memory hierarchy is critical for the performance of current processors. The performance of the memory hierarchy can be improved by means of program transformations such as loop tiling, which is a code transformation targeted to reduce capacity misses. This paper presents a novel systematic approach to perform nearoptimal loop tiling based on an accurate data locality analysis (Cache Miss Equations) and a powerful technique to search the solution space that is based on a genetic algorithm. The results show that this approach can remove practically all capacity misses for all considered benchmarks. The reduction of replacement misses results in a decrease of the miss ratio that can be as significant as a factor of 7 for the matrix multiply kernel.
Ranking and Optimization of Target Tracking Algorithms
, 2002
"... this dissertation isdev eloping a ranking and selection technique fore#ectiv ely comparing tracking algorithms that maintain target tracks after they hav e been initialized ..."
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Cited by 3 (1 self)
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this dissertation isdev eloping a ranking and selection technique fore#ectiv ely comparing tracking algorithms that maintain target tracks after they hav e been initialized
Early P/G Grid Voltage Integrity Verification
, 2010
"... As part of power delivery network verification, one should check if the voltage fluctuations exceed some critical threshold. In this work, we consider the power and ground grids together and describe an early verification approach under the framework of current constraints where tight lower and uppe ..."
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Cited by 3 (1 self)
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As part of power delivery network verification, one should check if the voltage fluctuations exceed some critical threshold. In this work, we consider the power and ground grids together and describe an early verification approach under the framework of current constraints where tight lower and upper bounds on worstcase voltage fluctuations are computed via linear programs. Experimental results indicate that the proposed technique results in errors in the range of a few mV.
Effective use of phrases in language modeling to improve information retrieval
 2004 Symposium on AI & Math Special Session on Intelligent Text Processing
, 2004
"... Traditional information retrieval models treat the query as a bag of words, assuming that the occurrence of each query term is independent of the positions and occurrences of others. Several of these traditional models have been extended to incorporate positional information, most often through the ..."
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Cited by 2 (1 self)
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Traditional information retrieval models treat the query as a bag of words, assuming that the occurrence of each query term is independent of the positions and occurrences of others. Several of these traditional models have been extended to incorporate positional information, most often through the inclusion of phrases. This has shown improvements in effectiveness on large, modern test collections. The language modeling approach to information retrieval is attractive because it provides a wellstudied theoretical framework that has been successful in other fields. Incorporating positional information into language models is intuitive and has shown significant improvements in several languagemodeling applications. However, attempts to integrate positional information into the languagemodeling approach to IR have not shown consistent significant improvements. This paper provides a broader exploration of this problem. We apply the backoff technique to incorporate a bigram phrase language model with the traditional unigram one and compare its performance to an interpolation of a conditional bigram model with the unigram model. While this novel application of backoff does not improve effectiveness, we find that our formula for interpolating a conditional bigram model with the unigram model yields significantly different results from prior work. Namely, it shows an 11 % relative improvement in average precision on one query set, while yielding no improvement on the other two. 1.
SecurityAssured Resource Allocation for Trusted Grid Computing
, 2003
"... Abstract: A new trustbased model is developed for optimizing resource allocation in a distributed Grid computing environment. Highly shared resources in a Grid create the insecurity and dependability concerns that hinder distributed applications. We model the Grid resource allocation process as a m ..."
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Cited by 1 (1 self)
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Abstract: A new trustbased model is developed for optimizing resource allocation in a distributed Grid computing environment. Highly shared resources in a Grid create the insecurity and dependability concerns that hinder distributed applications. We model the Grid resource allocation process as a multiobjective integerprogramming problem. Trusted Grid computing power is maximized over multiple resources. At the same time, the aggregate cost of Grid services is minimized to yield a high performance/cost ratio. Our new SecurityAssured Resource Allocation (SARA) scheme enables dynamic resources under the security constraints. The Grid resources are assured with a distributed security infrastructure. First, we present the mathematical model for SARA optimization process. Then we use the Simplex method and branchandbound method to obtain optimal or suboptimal solutions. We illustrate the ideas with a working example of a pool of 11 host machines from 2 resource sites. For k resource sites with N machine hosts, our SARA algorithm has a search complexity O(2 k1 N/k), which is much lower than O(2 N) in exhaustive search for the optimal solutions. Our model can be applied to secure many Grid applications in scientific supercomputing or in cyberspace information services. Index Terms: Computational grids, distributed supercomputing, resource allocation, network security, trust models, dependable computing, integer programming, Simplex method, and branchandbound method. 1.
Modular Arithmetic Decision Procedure Id: madp.tex,v 1.13 2005/07/18 22:38:51 root Exp
"... All integer data types in programs (such as int, short, byte) have an underlying finite representation in hardware. This finiteness can result in subtle integeroverflow errors that are hard to reason about both for humans and analysis tools alike. As a first step towards finding such errors automat ..."
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All integer data types in programs (such as int, short, byte) have an underlying finite representation in hardware. This finiteness can result in subtle integeroverflow errors that are hard to reason about both for humans and analysis tools alike. As a first step towards finding such errors automatically, we will describe two modular arithmetic decision procedures for reasoning about bounded integers. We show how to deal with modular arithmetic operations and inequalities for both linear and nonlinear problems. Both procedures are suitable for integration with NelsonOppen framework [1, 2, 3]. The linear solver is composed of MüllerSeidl algorithm [4] and an arbitrary integer solver for solving preprocessed congruences and inequalities. For the nonlinear problems we use Newton’s padic iteration algorithm to progressively reason about the satisfiability of the input constraints modulo 2 k, for increasing k. We use a SAT solver only for the base case when k = 1. According to our knowledge, this is the first NelsonOppen decision procedure capable of reasoning about multiplication over bounded integers without converting the entire problem to a SAT instance.