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502528
Data mining with sparse grids using simplicial basis functions.
Recently we presented a new approach [18] to the classification problem arising in data mining. It is based on the regularization network approach but, in contrast to other methods which employ ansatz functions associated to data points, we use a grid in the usually high-dimensional feature space for the minimization p...
INTRODUCTION Data mining is the process of nding patterns, relations and trends in large data sets. Examples range from scien- tic applications like the post-processing of data in medicine or the evaluation of satellite pictures to nancial and commercial applications, e.g. the assessment of credit risks or the selectio...
data mining;classification;approximation;simplicial discretization;sparse grids;combination technique
502529
Mining time-changing data streams.
Most statistical and machine-learning algorithms assume that the data is a random sample drawn from a stationary distribution. Unfortunately, most of the large databases available for mining today violate this assumption. They were gathered over months or years, and the underlying processes generating them changed duri...
INTRODUCTION Modern organizations produce data at unprecedented rates; among large retailers, e-commerce sites, telecommunications providers, and scientic projects, rates of gigabytes per day are common. While this data can contain valuable knowledge, its volume increasingly outpaces practitioners' ability to mine it. ...
data streams;incremental learning;concept drift;decision trees;subsampling;hoeffding bounds
502532
Robust space transformations for distance-based operations.
For many KDD operations, such as nearest neighbor search, distance-based clustering, and outlier detection, there is an underlying &kgr;-D data space in which each tuple/object is represented as a point in the space. In the presence of differing scales, variability, correlation, and/or outliers, we may get unintuitive ...
INTRODUCTION For many KDD operations, such as nearest neighbor search, distance-based clustering, and outlier detection, there is an underlying k-D data space in which each tuple/object is represented as a point in the space. Often times, the tuple represented simply as the point in the k-D space. More formally, the tr...
data mining;robust statistics;space transformations;outliers;robust estimators;distance-based operations
502544
Evaluating the novelty of text-mined rules using lexical knowledge.
In this paper, we present a new method of estimating the novelty of rules discovered by data-mining methods using WordNet, a lexical knowledge-base of English words. We assess the novelty of a rule by the average semantic distance in a knowledge hierarchy between the words in the antecedent and the consequent of the ru...
Introduction A data-mining system may discover a large body of rules; however, relatively few of these may convey useful new knowledge to the user. Several metrics for evaluating the \interestingness" of mined rules have been proposed [BA99, HK01]. These metrics can be used to lter out a large percentage of the less in...
wordnet;interesting rules;knowledge hierarchy;novelty;semantic distance
502555
Generalized clustering, supervised learning, and data assignment.
Clustering algorithms have become increasingly important in handling and analyzing data. Considerable work has been done in devising effective but increasingly specific clustering algorithms. In contrast, we have developed a generalized framework that accommodates diverse clustering algorithms in a systematic way. This...
INTRODUCTION AND MOTIVATION Although most research on machine learning focuses on induction from supervised training data, there are many situations in which class labels are not available and which thus require unsupervised methods. One widespread approach to unsupervised induction involves clustering the training cas...
iterative optimization;clustering;supervised learning
502567
Detecting graph-based spatial outliers.
of outliers can lead to the discovery of unexpected, interesting, and useful knowledge. Existing methods are designed for detecting spatial outliers in multidimensional geometric data sets, where a distance metric is available. In this paper, we focus on detecting spatial outliers in graph structured data sets. We defi...
Introduction Data mining is a process to extract nontrivial, previously unknown and potentially useful infor- mation(such as knowledge rules, constraints, regularities) from data in databases [11, 4]. The explosive growth in data and databases used in business management, government administra- tion, and scientific dat...
outlier detection;spatial graphs;Spatial Data Mining
502591
Bipartite graph partitioning and data clustering.
Many data types arising from data mining applications can be modeled as bipartite graphs, examples include terms and documents in a text corpus, customers and purchasing items in market basket analysis and reviewers and movies in a movie recommender system. In this paper, we propose a new data clustering method based o...
INTRODUCTION analysis is an important tool for exploratory data mining applications arising from many diverse disciplines. Informally, cluster analysis seeks to partition a given data set into compact clusters so that data objects within a cluster are more similar than those in distinct clusters. The literature on clus...
singular value decomposition;graph partitioning;correspondence analysis;document clustering;spectral relaxation;bipartite graph
502609
Using navigation data to improve IR functions in the context of web search.
As part of the process of delivering content, devices like proxies and gateways log valuable information about the activities and navigation patterns of users on the Web. In this study, we consider how this navigation data can be used to improve Web search. A query posted to a search engine together with the set of pag...
INTRODUCTION Searching for information on the Web can be tedious. Traditional search engines like Lycos and Google now routinely return tens of thousands of resources per query. Navigating these lists can be time consuming and frustrating. In this paper, we propose narrowing search results by observing the browsing pat...
web searching;proxy access logs;model-based clustering;query clustering;expectation-maximization algorithm
502661
Scaling replica maintenance in intermittently synchronized mobile databases.
To avoid the high cost of continuous connectivity, a class of mobile applications employs replicas of shared data that are periodically updated. Updates to these replicas are typically performed on a client-by-client basis--that is, the server individually computes and transmits updates to each client--limiting scalabi...
INTRODUCTION Intermittently Synchronized Database (ISDB) systems allow mobile data sharing applications to reduce cost by forgoing continuous connectivity. To allow sharing, a dedicated update server maintains the primary copy (global database) of all data held by mobile clients while each client maintains its own repl...
distributed databases;mobile databases;intermittent synchronization
502784
Controllable morphing of compatible planar triangulations.
Two planar triangulations with a correspondence between the pair of vertex sets are compatible (isomorphic) if they are topologically equivalent. This work describes methods for morphing compatible planar triangulations with identical convex boundaries in a manner that guarantees compatibility throughout the morph. The...
Figure 7 shows this on a concrete example. Conjecture 3.5 allows to choose the maximum m, namely that guarantees a valid morph. A simple algorithm to flnd M sequentially checks morphs for every m > 1, incrementing m by 2. The number of morphs checked may be signiflcantly reduced to ACM Transactions on Graphics, Vol. X...
linear Morph;morphing;compatible triangulations;self-intersection elemination;controllable Morphing;isomorphic triangulations;local Control
502796
Application of aboutness to functional benchmarking in information retrieval.
Experimental approaches are widely employed to benchmark the performance of an information retrieval (IR) system. Measurements in terms of recall and precision are computed as performance indicators. Although they are good at assessing the retrieval effectiveness of an IR system, they fail to explore deeper aspects suc...
Summary In summary, the probabilistic model has the highest degree of potential precision, followed by the threshold vector space model, then the Boolean model and the nave vector space model. This conclusion is consistent with the experimental results. The motivation for this judgment lies in the varying degrees to w...
functional benchmarking;inductive evaluation;aboutness;logic-based information retrieval
503036
From checking to inference via driving and dag grammars.
Abramov and Glck have recently introduced a technique called URA for inverting first order functional programs. Given some desired output value, URA computes a potentially infinite sequence of substitutions/restrictions corresponding to the relevant input values. In some cases this process does not terminate.In the pre...
INTRODUCTION The program-transformation techniques collectively called supercompilation have been shown to eectively handle problems that partial evaluation and deforestation cannot han- dle. The apparent strength of supercompilation stems from driving the object programs, that is, speculatively unfolding expressions c...
supercompilation;program inversion;inference
503042
Mixed-initiative mixed computation.
We show that partial evaluation can be usefully viewed as a programming model for realizing mixed-initiative functionality in interactive applications. Mixed-initiative interaction between two participants is one where the parties can take turns at any time to change and steer the flow of interaction. We concentrate on...
INTRODUCTION Mixed-initiative interaction [8] has been studied for the past years in the areas of artificial intelligence (AI) planning [17], human-computer interaction [5], and discourse analysis [6]. As Novick and Sutton point out [13], it is 'one of those things that people think that they can recognize when they se...
mixed-initiative interaction;VoiceXML;interaction sequences;dialog management;partial evaluation
503068
Timing verification of dynamically reconfigurable logic for the xilinx virtex FPGA series.
This paper reports on a method for extending existing VHDL design and verification software available for the Xilinx Virtex series of FPGAs. It allows the designer to apply standard hardware design and verification tools to the design of dynamically reconfigurable logic (DRL). The technique involves the conversion of a...
INTRODUCTION In dynamically reconfigurable logic (DRL), a circuit or system is adapted over time. This presents additional design and verification problems to those of conventional hardware design [1] that standard tools cannot cope with directly. For this reason, DRL design methods typically involve the use of a mixtu...
run-time reconfiguration;verification;dynamic reconfiguration;FPGA
503224
The structure and value of modularity in software design.
The concept of information hiding modularity is a cornerstone of modern software design thought, but its formulation remains casual and its emphasis on changeability is imperfectly related to the goal of creating added value in a given context. We need better explanatory and prescriptive models of the nature and value ...
Figure 1: An elementary DSM with three design parameters. Groups of interdependent design parameters are clustered into a proto-module to show that the decisions are managed collectively as a single design task (See Figure 2; the dark lines denote the desired proto-module clusters). In essence, such a proto-module is ...
modularity;design structure matrix;real options;software
503244
Coverage criteria for GUI testing.
A widespread recognition of the usefulness of graphical user interfaces (GUIs) has established their importance as critical components of today's software. GUIs have characteristics different from traditional software, and conventional testing techniques do not directly apply to GUIs. This paper's focus is on coverage ...
INTRODUCTION The importance of graphical user interfaces (GUIs) as critical components of today's software is increasing with the recognition of their usefulness. The widespread use of GUIs has led to the construction of more and more complex GUIs. Although the use of GUIs continues to grow, GUI testing has, until rece...
component testing;integration tree;event-flow graph;event-based coverage;GUI testing;GUI test coverage
503246
An empirical study on the utility of formal routines to transfer knowledge and experience.
Most quality and software process improvement frameworks emphasize written (i.e. formal) documentation to convey recommended work practices. However, there is considerable skepticism among developers to learn from and adhere to prescribed process models. The latter are often perceived as overly "structured" or implying...
Figure 1. A model of knowledge conversion between tacit and explicit knowledge [27]. Figure 1 expresses that practitioners first internalize new knowledge (i.e. individual learning). The new knowledge is then socialized into revised work processes and changed behavior (group learning). The new work processes and the...
knowledge transfer;software process improvement;knowledge management;formal routines;developer attitudes
503505
Featherweight Java.
Several recent studies have introduced lightweight versions of Java: reduced languages in which complex features like threads and reflection are dropped to enable rigorous arguments about key properties such as type safety. We carry this process a step further, omitting almost all features of the full language (includi...
Introduction "Inside every large language is a small language struggling to get out." Formal modeling can offer a significant boost to the design of complex real-world artifacts such as programming languages. A formal model may be used to describe some aspect of a design precisely, to state and prove its properties, an...
language design;compilation;generic classes;language semantics
504212
Analysis and comparison of two general sparse solvers for distributed memory computers.
This paper provides a comprehensive study and comparison of two state-of-the-art direct solvers for large sparse sets of linear equations on large-scale distributed-memory computers. One is a multifrontal solver called MUMPS, the other is a supernodal solver called superLU. We describe the main algorithmic features of ...
Introduction We consider the direct solution of sparse linear equations on distributed memory computers where communication is by message passing, normally using MPI. We study in detail two state-of-the-art solvers, MUMPS (Amestoy, Duff, L'Excellent and Koster 1999, Amestoy, Duff and L'Excellent 2000) and SuperLU (Li a...
sparse direct solvers;multifrontal and supernodal factorizations;parallelism;distributed-memory computers
504225
The look of the link - concepts for the user interface of extended hyperlinks.
The design of hypertext systems has been subject to intense research. Apparently, one topic was mostly neglected: how to visualize and interact with link markers. This paper presents an overview of pragmatic historical approaches, and discusses problems evolving from sophisticated hypertext linking features. Blending t...
Figure 1: HyperTIES used cyan to highlight links [from Shneiderman & Kearsley 1989] HyperTIES (Fig. 1) avoided this problem by using a distinct text color for link markers, similar to Hyper-G's browser Harmony (Fig. 5) which utilized background colors [Shneiderman & Kearsley 1989; Andrews 1996]. This has the advantage...
XLink;user interface;distributed hypertext;link marker
504364
Class-is-type is inadequate for object reuse.
It is well known that class and type are two different concepts in object-oriented programming languages (OOPLs). However, in many popular OOPLs, classes are used as types. In this paper, we argue that the class-is-type principle is a major obstacle to software reuse, especially to object reuse. The concepts of the bas...
Introduction Object-oriented languages and technology have propelled software reuse to an unprecedented level. However, software reuse at the current stage is still mostly (1) within a single software project and (2) in the form of source-code reuse and as libraries. The dream that software construction would be simila...
kinds;object reuse;classes;kind-bounded polymorphism;parameterized types;generic functions;types;objects;class-is-type principle
504535
Minimal cover-automata for finite languages.
A cover-automaton A of a finite language L &Sgr; is a finite deterministic automaton (DFA) that accepts all words in L and possibly other words that are longer than any word in L. A minimal deterministic finite cover automaton (DFCA) of a finite language L usually has a smaller size than a minimal DFA that accepts L. T...
Introduction Regular languages and finite automata are widely used in many areas such as lexical analysis, string matching, circuit testing, image compression, and parallel processing. However, many applications of regular languages use actually only finite languages. The number of states of a finite automaton that acc...
finite languages;deterministic cover automata;deterministic finite automata;cover language;finite automata
504537
Normal form algorithms for extended context-free grammars.
We investigate the complexity of a variety of normal-form transformations for extended context-free grammars, where by extended we mean that the set of right-hand sides for each nonterminal in such a grammar is a regular set. The study is motivated by the implementation project GraMa which will provide a C++ toolkit fo...
Introduction In the 1960's, extended context-free grammars were introduced, based on Backus-Naur form, as a useful abbreviatory notation that made context-free grammars easier to write. More recently, the Standardized General Markup Language (SGML) [16] used a similar abbrevia- tory notation to define extended context-...
grammatical representations;complexity;efficient algorithms;normal forms;symbolic manipulation;extended context-free grammars
504540
Using acceptors as transducers.
We wish to use a given nondeterministic two-way multi-tape acceptor as a transducer by supplying the contents for only some of its input tapes, and asking it to generate the missing contents for the other tapes. We provide here an algorithm for assuring beforehand that this transduction always results in a finite set o...
Introduction In this paper we study the following problem: assume that we are given a nondeterministic two-way multi-tape acceptor A and a subset X of its tapes. We would like to use A no longer as an acceptor which receives input on all its tapes, but instead as a kind of transducer [15, Chapter 2.7] which receives in...
transducers;finiteness dependencies;multi-tape automata
504552
A new lower bound for the list update problem in the partial cost model.
The optimal competitive ratio for a randomized online list update algorithm is known to be at least 1.5 and at most 1.6, but the remaining gap is not yet closed. We present a new lower bound of 1.50084 for the partial cost model. The construction is based on game trees with incomplete information, which seem to be gene...
Introduction The list update problem is a classical online problem in the area of self-organizing data structures [4]. Requests to items in an unsorted linear list must be served while maintaining the list so that access costs remain small. We assume the partial cost model where accessing the ith item in the list incur...
list-update;analysis of algorithms;competitive analysis;on-line algorithms
504560
Online request server matching.
In the following paper an alternative online variant of the matching problem in bipartite graphs is presented. It is triggered by a scheduling problem. There, a task is unknown up to its disclosure. However, when a task is revealed, it is not necessary to take a decision on the service of that particular task. On the c...
Introduction In this report we study a model which was developed for a rather simple scheduling problem. Consider a single resource and a discrete time model. The resource is available for one unit in every time step. In the following this resource is called server. Every time step a task can occur that has a demand of...
competitive analysis;online scheduling;online bipontite matching
504566
Reductions for non-clausal theorem proving.
This paper presents the TAS methodology as a new framework for generating non-clausal Automated Theorem Provers. We present a complete description of the ATP for Classical Propositional Logic, named TAS-D, but the ideas, which make use of implicants and implicates can be extended in a natural manner to first-order logi...
Introduction Much research in automated theorem proving has been focused on developing satisfiability testers for sets of clauses. However, experience has pointed out a number of disadvantages of this it is not natural to specify a real-world problem in clause form, the translation into clause form is not easy to handl...
SAT problem;prime implicates/implicants;non-clausal theorem proving
504571
A typed context calculus.
This paper develops a typed calculus for contexts i.e., lambda terms with "holes". In addition to ordinary lambda terms, the calculus contains labeled holes, hole abstraction and context application for manipulating first-class contexts. The primary operation for contexts is hole-filling, which captures free variables....
Introduction A context in the lambda calculus is a term with a \hole" in it. The operation for contexts is to ll the hole of a context with a term. For the purpose of 1 This is the authors' version of the article to appear in Theoretical Computer Science. current a-liation: Department of Information Science, University...
alpha-renaming;lambda-calculus;type system;context
504573
Tractable disjunctions of linear constraints.
We study the problems of deciding consistency and performing variable elimination for disjunctions of linear inequalities and disequations with at most one inequality per disjunction. This new class of constraints extends the class of generalized linear constraints originally studied by Lassez and McAloon. We show that...
Introduction Linear constraints over the reals have recently been studied in depth by researchers in constraint logic programming (CLP) and constraint databases (CDB) [JM94, KKR95, Kou94c]. Two very important operations in CLP and CDB systems are deciding consistency of a set of constraints, and performing variable eli...
global consistency;ORD-horn constraints;variable elimination;linear constraints;interval algebra
504577
Loop checks for logic programs with functions.
Two complete loop checking mechanisms have been presented in the literature for logic programs with functions: OS-check and EVA-check. OS-check is computationally efficient but quite unreliable in that it often misidentifies infinite loops, whereas EVA-check is reliable for a majority of cases but quite expensive. In t...
Introduction The recursive nature of logic programs leads to possibilities of running into innite loops with top-down query evaluation. By an innite loop we refer to any innite SLD-derivation. An illustrative example is the evaluation of the goal p(a) against the logic program which leads to the innite loop Another ver...
logic programming;loop checking
504580
Partial correctness for probabilistic demonic programs.
Recent work in sequential program semantics has produced both an operational (He et al., Sci. Comput. Programming 28(2, and an axiomatic (Morgan et al., ACM Trans. Programming Languages Systems 18(3) (1996) 325-353; Seidel et al., Tech Report PRG-TR-6-96, Programming Research group, February 1996) treatment of total co...
Introduction Deterministic computation over a state space S can be modelled as functions of type S ! S, from initial to final states. A 'powerdomain' construction extends that to nondeterminism, and although the traditional powerdomains - Smyth, Hoare and Plotkin - differ in their treatment of non-termination, they all...
program logic;partial correctness;probability;verification
504618
Loss probability calculations and asymptotic analysis for finite buffer multiplexers.
In this paper, we propose an approximation for the loss probability, PL (x), in a finite buffer system with buffer size x. Our study is motivated by the case of a high-speed network where a large number of sources are expected to be multiplexed. Hence, by appealing to Central Limit Theorem type of arguments, we model t...
Introduction loss probability is an important QoS (Quality of Service) measure in communication networks. While the overflow probability, or the tail of the queue length dis- tribution, in an infinite bu#er system has been extensively studied [1], [2], [3], [4], [5], [6], [7], there have been relatively few studies on ...
maximum variance asymptotic;asymptotic relationship;queue length distribution;loss probability
504633
QoS provisioning and tracking fluid policies in input queueing switches.
The concept of tracking fluid policies by packetized policies is extended to input queueing switches. It is considered that the speedup of the switch is one. One of the interesting applications of the tracking policy in TDMA satellite switches is elaborated. For the special case of 2 2 switches, it is shown that a tra...
INTRODUCTION One of the main issues in the design of integrated service networks is to provide the service performance requirements for a broad range of applications. Applications requirements are translated into network quantitative parameters. The most common performance measures are packet loss probability, delay, a...
QoS provisioning;input-queued switching;scheduling
504641
performance over end-to-end rate control and stochastic available capacity.
Motivated by TCP over end-to-end ABR, we study the performance of adaptive window congestion control, when it operates over an explicit feedback rate-control mechanism, in a situation in which the bandwidth available to the elastic traffic is stochastically time varying. It is assumed that the sender and receiver of th...
Introduction bottleneck link xmitter recvr ABR recvr end-to-end ABR source ABR Figure 1: The network under study has a large round trip delay and a single congested link in the path of the connection. The ABR connection originates at the host and ends at the destination node. We call this scenario "end-to-end" ABR. T...
TCP over ABR;congestion control;TCP performance
504650
Jitter control in QoS networks.
We study jitter control in networks with guaranteed quality of service (QoS) from the competitive analysis point of view: we propose on-line algorithms that control jitter and compare their performance to the best possible (by an off-line algorithm) for any given arrival sequence. For delay jitter, where the goal is to...
Introduction The need for networks with guaranteed quality of service (QoS) is widely recognized today (see, e.g., [8, 11]). Unlike today's ``best effort'' networks such as the Internet, where the user has no guarantee on the performance it may expect from the network, QoS networks guarantee the end-user application a ...
buffer overflow and underflow;competitive analysis;streaming connections;jitter control;quality of service networks
504917
Prefetching for improved bus wrapper performance in cores.
Reuse of cores can reduce design time for systems-on-a-chip. Such reuse is dependent on being able to easily interface a core to any bus. To enable such interfacing, many propose separating a core's interface from its internals by using a bus wrapper. However, this separation can lead to a performance penalty when read...
Overview Separating a core's interface behavior and internal behavior can lead to performance penalties. For example, consider the core architectures shown in Figures 1(a), 1(b) and 1(c), showing a core with no bus wrapper, a core with a bus wrapper (BW) but without prefetching, and a core with a BW with prefetching...
PVCI;VSIA;system-on-a-chip;interfacing;cores;bus wrapper;on-chip bus;design reuse;intellectual property
505243
An optimal minimum spanning tree algorithm.
We establish that the algorithmic complexity of the minimum spanning tree problem is equal to its decision-tree complexity. Specifically, we present a deterministic algorithm to find a minimum spanning tree of a graph with n vertices and m edges that runs in time O(T*(m,n)) where T* is the minimum number of edge-weight...
Introduction The minimum spanning tree (MST) problem has been studied for much of this century and yet despite its apparent simplicity, the problem is still not fully understood. Graham and Hell [GH85] give an excellent survey of results from the earliest known algorithm of Boruvka [Bor26] to the invention of Fibonacci...
optimal complexity;graph algorithms;minimum spanning tree
505422
Closing the smoothness and uniformity gap in area fill synthesis.
Control of variability in the back end of the line, and hence in interconnect performance as well, has become extremely difficult with the introduction of new materials such as copper and low-k dielectrics. Uniformity of chemical-mechanical planarization (CMP) requires the addition of area fill geometries into the layo...
INTRODUCTION Chemical-mechanical planarization (CMP) and other manufacturing steps in nanometer-scale VLSI processes have varying effects on device and interconnect features, depending on the local characteristics of the layout. To improve manufacturability and performance predictability, foundry rules require that a l...
monte-carlo;dummy fill problem;VLSI manufacturability;density analysis;chemical-mechanical polishing
505522
High-speed architectures for Reed-Solomon decoders.
New high-speed VLSI architectures for decoding Reed-Solomon codes with the Berlekamp-Massey algorithm are presented in this paper. The speed bottleneck in the Berlekamp-Massey algorighm is in the iterative computation of discrepencies followed by the updating of the error-locator polynomial. This bottleneck is eliminat...
Introduction Reed-Solomon codes [1], [3] are employed in numerous communications systems such as those for deep space, digital subscriber loops, and wireless systems as well as in memory and data storage systems. Continual demand for ever higher data rates makes it necessary to devise very high-speed implementations of...
systolic architectures;interleaved codes;berlekamp-massey algorithm;pipelined decoders;reed-solomon codes
505524
Delay fault testing of IP-based designs via symbolic path modeling.
Predesigned blocks called intellectual property (IP) cores are increasingly used for complex system-on-a-chip (SOC) designs. The implementation details of IP cores are often unknown or unavailable, so delay testing of such designs is difficult. We propose a method that can test paths traversing both IP cores and user-d...
Introduction While reusable predesigned circuits called intellectual property (IP) circuits or cores are becoming increasingly popular for VLSI system-on-a-chip (SOC) designs [1, 3, 8, 11, 12, 14, 21], they present difficult testing problems that existing methodologies cannot adequately handle. Path delay verification ...
automatic test pattern generation ATPG;binary decision diagram BDD decomposition;system-on-a-chip SOC;delay fault testing;intellectual property IP core testing
505588
An algebraic approach to IP traceback.
We present a new solution to the problem of determining the path a packet traversed over the Internet (called the traceback problem) during a denial-of-service attack. This article reframes the traceback problem as a polynomial reconstruction problem and uses algebraic techniques from coding theory and learning theory ...
Introduction A denial of service attack is designed to prevent legitimate access to a resource. In the context of the Internet, an attacker can "flood" a victim's connection with random packets to prevent legitimate packets from getting through. These Internet denial of service attacks have become more prevalent recent...
traceback;internet protocol
505628
Extraction and Optimization of B-Spline PBD Templates for Recognition of Connected Handwritten Digit Strings.
Recognition of connected handwritten digit strings is a challenging task due mainly to two problems: poor character segmentation and unreliable isolated character recognition. In this paper, we first present a rational B-spline representation of digit templates based on Pixel-to-Boundary Distance (PBD) maps. We then pr...
Introduction In the field of researching on automated handwritten document processing system, hand-written digit recognition still poses a very challenge to scientists and practitioners. The difficulties arise not only from the different ways in which the single digit can be written, but also from varying requirements ...
template optimization;evolutionary algorithm;nearest neighbor classifier;digit templates;pixel-to-boundary distance map;connected handwritten digit recognition;multilayer perceptron classifier;b-spline fitting
505929
Local search characteristics of incomplete SAT procedures.
Effective local search methods for finding satisfying assignments of CNF formulae exhibit several systematic characteristics in their search. We identify a series of measurable characteristics of local search behavior that are predictive of problem solving efficiency. These measures are shown to be useful for diagnosin...
Introduction Since the introduction of GSAT (Selman, Levesque, & Mitchell 1992) there has been considerable research on local search methods for finding satisfying assignments for CNF formulae. These methods are surprisingly effective; they can often find satisfying assignments for large CNF formulae that are far beyon...
constraint satisfication;experimental analysis;satisfiability;local search
505996
Improving Latency Tolerance of Multithreading through Decoupling.
AbstractThe increasing hardware complexity of dynamically scheduled superscalar processors may compromise the scalability of this organization to make an efficient use of future increases in transistor budget. SMT processors, designed over a superscalar core, are therefore directly concerned by this problem. This work ...
Introduction The gap between the speeds of processors and memories has kept increasing in the past decade and it is expected to sustain the same trend in the near future. This divergence implies, in terms of clock cycles, an increasing latency of those memory operations that cross the chip boundaries. In addition, proc...
simultaneous multithreading;instruction-level parallelism;hardware complexity;latency hiding;access/execute decoupling
506024
Fault Detection for Byzantine Quorum Systems.
AbstractIn this paper, we explore techniques to detect Byzantine server failures in asynchronous replicated data services. Our goal is to detect arbitrary failures of data servers in a system where each client accesses the replicated data at only a subset (quorum) of servers in each operation. In such a system, some co...
Introduction Data replication is a well-known means of protecting against data unavailability or corruption in the face of data server failures. When servers can suffer Byzantine (i.e., arbitrary) failures, the foremost approach for protecting data is via state machine replication [Sch90], in which every correct server...
byzantine fault tolerance;replicated data;fault detection;quorum systems
506154
Task assignment with unknown duration.
We consider a distributed server system and ask which policy should be used for assigning jobs (tasks) to hosts. In our server, jobs are not preemptible. Also, the job's service demand is not known a priori. We are particularly concerned with the case where the workload is heavy-tailed, as is characteristic of many emp...
Introduction In recent years, distributed servers have become commonplace because they allow for increased computing power while being cost-effective and easily scalable. In a distributed server system, requests for service (tasks) arrive and must be assigned to one of the host machines for processing. The rule for ass...
load sharing;fairness;job scheduling;supercomputing;distributed servers;contrary behavior;high variance;load balancing;task assignment;heavy-tailed workloads;clusters
506161
Mesh Partitioning for Efficient Use of Distributed Systems.
Mesh partitioning for homogeneous systems has been studied extensively; however, mesh partitioning for distributed systems is a relatively new area of research. To ensure efficient execution on a distributed system, the heterogeneities in the processor and network performance must be taken into consideration in the par...
Introduction Distributed computing has been regarded as the future of high performance computing. Nation-wide high speed networks such as vBNS [25] are becoming widely available to interconnect high-speed computers, virtual environments, scientific instruments and large data sets. Projects such as Globus [15] and Legio...
simulated annealing;distributed systems;mesh partitioning
506198
Speculative Versioning Cache.
Dependences among loads and stores whose addresses are unknown hinder the extraction of instruction level parallelism during the execution of a sequential program. Such ambiguous memory dependences can be overcome by memory dependence speculation which enables a load or store to be speculatively executed before the add...
Introduction Modern microprocessors extract instruction level parallelism (ILP) from sequential programs by issuing instructions from an active instruction window. Data dependences among instructions, and not the original program order, determine when an instruction may be issued from the win- dow. Dependences involvin...
speculative versioning;memory disambiguation;snooping cache coherence protocols;speculative memory
506342
Strong normalizability of the non-deterministic catch/throw calculi.
The catch/throw mechanism in Common Lisp provides a simple control mechanism for non-local exits. We study typed calculi by Nakano and Sato which formalize the catch/throw mechanism. These calculi correspond to classical logic through the Curry-Howard isomorphism, and one of their characteristic points is that they hav...
Introduction The catch and throw mechanism provides a means to implement non-local exits. The following simple example written in Common Lisp [19] shows how to use the catch and throw mechanism: (defun multiply (x) (catch 'zero (multiply2 x))) (defun multiply2 (x) (if (null x) 1 (if (= (car x) (* (car x) (multiply2 (cd...
catch and throw;classical logic;type system;strong normalizability
506345
Least and greatest fixed points in intuitionistic natural deduction.
This paper is a comparative study of a number of (intensional-semantically distinct) least and greatest fixed point operators that natural-deduction proof systems for intuitionistic logics can be extended with in a proof-theoretically defendable way. Eight pairs of such operators are analysed. The exposition is centred...
Introduction This paper is a comparative study of a number of least and greatest xed point operators, or inductive and coinductive denition operators, that natural- deduction (n.d.) proof systems for intuitionistic logics (typed lambda calculi with product and sum types) can be extended with as logical constants (type-...
coding styles;least and greatest fixed points;coinductive types;schemes of total corecursion;typed lambda calculi;natural deduction
506696
Skepticism and floating conclusions.
The purpose of this paper is to question some commonly accepted patterns of reasoning involving nonmonotonic logics that generate multiple extensions. In particular, I argue that the phenomenon of floating conclusions indicates a problem with the view that the skeptical consequences of such theories should be identifie...
Introduction One of the most striking ways in which nonmonotonic logics can differ from classical logic, and even from standard philosophical logics, is in allowing for multiple sanctioned conclusion sets, known as extensions. The term is due to Reiter [12], who thought of default rules as providing a means for extendi...
default logic;nonmonotonic logic;skeptical reasoning
506794
Anomaly Detection in Embedded Systems.
By employing fault tolerance, embedded systems can withstand both intentional and unintentional faults. Many fault-tolerance mechanisms are invoked only after a fault has been detected by whatever fault-detection mechanism is used, hence, the process of fault detection must itself be dependable if the system is expecte...
Introduction As computer systems become more miniaturized and more pervasive, they will be embedded in everyday devices with increasing frequency, even to the point at which domestic and industrial consumers may not be aware of their presence. Some truck tires, for example, will soon have a processor and a pressure sen...
coverage;anomaly;dependability;anomaly detection
506833
Optimal partition of QoS requirements on unicast paths and multicast trees.
We investigate the problem of optimal resource allocation for end-to-end QoS requirements on unicast paths and multicast trees. Specifically, we consider a framework in which resource allocation is based on local QoS requirements at each network link, and associated with each link is a cost function that increases with...
INTRODUCTION Broadband integrated services networks are expected to support multiple and diverse applications, with various quality of service (QoS) requirements. Accordingly, a key issue in the design of broadband architectures is how to provide the resources in order to meet the requirements of each connection. Suppo...
routing;broadband networks;convex costs;QoS partitioning;QoS-dependent costs;multicast;unicast
506837
Generalized loop-back recovery in optical mesh networks.
Current means of providing loop-back recovery, which is widely used in SONET, rely on ring topologies, or on overlaying logical ring topologies upon physical meshes. Loop-back is desirable to provide rapid preplanned recovery of link or node failures in a bandwidth-efficient distributed manner. We introduce generalized...
Introduction For WDM networks to oer reliable high-bandwidth services, automatic self-healing capabilities, similar to those provided by SONET, are required. In particular, pre-planned, ultrafast restoration of service after failure of a link or node is required. As WDM networks mature and expand, the need has emerged ...
mesh networks;WDM;loop-back;network restoration
506843
A mutual exclusion algorithm for ad hoc mobile networks.
A fault-tolerant distributed mutual exclusion algorithm that adjusts to node mobility is presented, along with proof of correctness and simulation results. The algorithm requires nodes to communicate with only their current neighbors, making it well-suited to the ad hoc environment. Experimental results indicate that a...
Introduction A mobile ad hoc network is a network wherein a pair of nodes communicates by sending messages either over a direct wireless link, or over a sequence of wireless links including one or more intermediate nodes. Direct communication is possible only between pairs of nodes that lie within one another's transmi...
mobile computing;mutual exclusion;distributed algorithm;ad hoc network
506896
Replication requirements in mobile environments.
Replication is extremely important in mobile environments because nomadic users require local copies of important data. However, today's replication systems are not "mobile-ready". Instead of improving the mobile user's environment, the replication system actually hinders mobility and complicates mobile operation. Desi...
Introduction Mobile computing is rapidly becoming standard in all types of environments: academic, com- mercial, and private. Widespread mobility impacts multiple arenas, but one of particular importance is data replication. Replication is especially important in mobile environments, since disconnected or poorly connec...
mobile computing;file systems;replication
506906
Negotiation-based protocols for disseminating information in wireless sensor networks.
In this paper, we present a family of adaptive protocols, called SPIN (Sensor Protocols for Information via Negotiation), that efficiently disseminate information among sensors in an energy-constrained wireless sensor network. Nodes running a SPIN communication protocol name their data using high-level data descriptors...
Introduction Wireless networks of sensors are likely to be widely deployed in the future because they greatly extend our ability to monitor and control the physical environment from remote lo- cations. Such networks can greatly improve the accuracy of information obtained via collaboration among sensor nodes and online...
negotiation-based protocols;energy-efficient protocols;meta-data;wireless sensor networks;information dissemination
507059
The Impulse Memory Controller.
AbstractImpulse is a memory system architecture that adds an optional level of address indirection at the memory controller. Applications can use this level of indirection to remap their data structures in memory. As a result, they can control how their data is accessed and cached, which can improve cache and bus utili...
Introduction Since 1987, microprocessor performance has improved at a rate of 55% per year; in contrast, latencies have improved by only 7% per year, and DRAM bandwidths by only 15-20% per year [17]. the result is that the relative performance impact of memory accesses continues to grow. In addition, as instruction iss...
computer architecture;memory systems
507198
Worst and Best Irredundant Sum-of-Products Expressions.
AbstractIn an irredundant sum-of-products expression (ISOP), each product is a prime implicant (PI) and no product can be deleted without changing the function. Among the ISOPs for some function $f$, a worst ISOP (WSOP) is an ISOP with the largest number of PIs and a minimum ISOP (MSOP) is one with the smallest number....
2. MSOP : STn; k n . 3. Proof. See the Appendix. tu In the proof of Lemma 2.1, we showed that which is six more than the lower bound given in 3 of Theorem 3.1. Therefore, for n 7 and k 3, the lower bound is not tight. However, for k 1, the lower bound is exact. That is, Theorem 3.2. 2: Proof. See the proof of Theor...
symmetric functions;worst sum-of-products expressions;prime implicants;logic minimization;multiple-output functions;minimum sum-of-products expressions;graph enumeration;irredundant sum-of-products;heuristic minimization;complete sum-of-products expressions;minimally strongly connected digraphs
507237
A logical foundation for deductive object-oriented databases.
Over the past decade, a large number of deductive object-oriented database languages have been proposed. The earliest of these languages had few object-oriented features, and more and more features have systematically been incorporated in successive languages. However, a language with a clean logical semantics that nat...
Introduction The objective of deductive object-oriented databases is to combine the best of the deductive and object-oriented ap- proaches, namely to combine the logical foundation of the deductive approach with the modeling capabilities of the object-oriented approach. Based on the deductive object-oriented database l...
deductive databases;nonmonotonic multiple inheritance;declarative semantics;object-oriented databases;rule-based languages
507257
The regular viewpoint on PA-processes.
PA is the process algebra allowing non-determinism, sequential and parallel compositions, and recursion. We suggest viewing PA-processes astrees, and usingtree-automata techniques for verification problems on PA. Our main result is that the set of iterated predecessors of a regular set of PA-processes is a regular tree...
Introduction Veri-cation of In-nite State Processes is a very active -eld of research today in the concurrency-theory community. Of course, there has always been an active Petri-nets com- munity, but researchers involved in process algebra and model-checking really became interested into in-nite state processes after t...
verification of infinite-state systems;process algebra;tree automata
507259
Axioms for real-time logics.
This paper presents a complete axiomatization of two decidable propositional real-time linear temporal logics: Event Clock Logic (EventClockTL) and Metric Interval Temporal Logic with past (MetricIntervalTL). The completeness proof consists of an effective proof building procedure for EventClockTL. From this result we ...
Introduction Many real-time systems are safety-critical, and therefore deserve to be specified with mathematical precision. To this end, real-time linear temporal logics [5] have been proposed and served as the basis of specification languages. preliminary version of this paper appeared in the Proceedings of the Tenth ...
axiomatization;completeness;real time;temporal logic
507260
From rewrite rules to bisimulation congruences.
The dynamics of many calculi can be most clearly defined by a reduction semantics. To work with a calculus, however, an understanding of operational congruences is fundamental; these can often be given tractable definitions or characterisations using a labelled transition semantics. This paper considers calculi with ar...
Introduction The dynamic behaviour of many calculi can be defined most clearly by a reduction semantics, comprising a set of rewrite rules, a set of reduction contexts in which they may be applied, and a structural congruence. These define the atomic internal reduction steps of terms. To work with a calculus, however, ...
term rewriting;bisimuation;operational congruences;labelled transition systems;process calculi;operational sematics
507274
Communication complexity method for measuring nondeterminism in finite automata.
While deterministic finite automata seem to be well understood, surprisingly many important problems concerning nondeterministic finite automata (nfa's) remain open. One such problem area is the study of different measures of nondeterminism in finite automata and the estimation of the sizes of minimal nondeterministic ...
Introduction In this paper the classical models of one-way nite automata (dfa's) and their nondeterministic counterparts (nfa's) [RS59] are investigated. While the structure and fundamental properties of dfa's are well understood, this is not the case for nfa's. For instance, we have ecient algorithms for constructing ...
nondeterminism;limited ambiguity;descriptional complexity;communication complexity;finite automata
507384
On first-order topological queries.
One important class of spatial database queries is the class of topological queries, that is, queries invariant under homeomorphisms. We study topological queries expressible in the standard query language on spatial databases, first-order logic with various amounts of arithmetic. Our main technical result is a combina...
Introduction The expressive power of first-order logic over finite relational databases is now well understood [AHV95, EF95]. Much less is known in spatial databases (also called constraint databases), where the relations are no longer finite but finitely represented [KLP99]. The notion of genericity (invariance of que...
constraint databases;first-order logic;topological queries
507385
Probabilistic game semantics.
A category of HO/N-style games and probabilistic strategies is developed where the possible choices of a strategy are quantified so as to give a measure of the likelihood of seeing a given play. A two-sided die is shown to be universal in this category, in the sense that any strategy breaks down into a composition betw...
Introduction Consider the fixpoint expression Y(x:(1 or x)). This can have two very different meanings attached. If, by or, it is meant that both sides can happen with, say, equal chances almost surely, we'll get the result 1. If, on the other hand, it is meant only that either can happen-but we don't know which-then t...
probabilistic Idealized Algol;games semantics
507388
Back and forth between guarded and modal logics.
Guarded fixed-point logic GF extends the guarded fragment by means of least and greatest fixed points, and thus plays the same role within the domain of guarded logics as the modal -calculus plays within the modal domain. We provide a semantic characterization of GF within an appropriate fragment of second-order logic,...
Introduction Guarded logics generalise certain features and desirable model theoretic properties of modal logics to a much wider context. The concept of guarded quantification was introduced by Andr-eka, van Benthem, and N-emeti [1], who proposed and analysed the guarded fragment of first-order logic, GF. This fragment...
modal logic;bisimulation;model theory;guarded logic
507449
On the Quality of Service of Failure Detectors.
Editor's Note: This paper unfortunately contains some errors which led to the paper being reprinted in the May 2002 issue. Please see IEEE Transactions on Computers, vol. 51, no. 5, May 2002, pp. 561-580 for the correct paper (available without subscription).We study the quality of service (QoS) of failure detectors. B...
Introduction Fault-tolerant distributed systems are designed to provide reliable and continuous service despite the failures of some of their components. A basic building block of such systems is the failure detector. Failure detectors are used in a wide variety of settings, such as network communication protocols [10]...
probabilistic analysis;failure detectors;quality of service;fault tolerance;distributed algorithm
507478
Visual Input for Pen-Based Computers.
The design and implementation of a camera-based, human-computer interface for acquisition of handwriting is presented. The camera focuses on a standard sheet of paper and images a common pen; the trajectory of the tip of the pen is tracked and the contact with the paper is detected. The recovered trajectory is shown to...
writing, and adopt the machine's ones: typing, mouse-clicking, knob-turning. Learning to use a keyboard eectively requires time and patience. Ditto for menu-based mouse inter- faces. Current interfaces were designed for habitual computer users and for a limited range of tasks. If the \computer revolution" is to reach a...
pen-based interface;systems and applications;pen-based computing;active and real-time vision
507649
Generic validation of structural content with parametric modules.
We demonstrate a natural mapping from XML element types to ML module expressions. The mapping is inductive and definitions of common XML operations can be derived as the module expressions are composed. We show how to derive, in a generic way, the validation function, which checks an XML document for conformance to its...
INTRODUCTION &MOTIVATION XML (eXtensible Markup Language) is language for tagging documents for their structural content [2]. A XML document is tagged into a tree of nested elements. XML is extensible because each XML document can include a DTD (Doc- ument Type which lists the tags of the elements and specifies the tag...
fixed points;functional programming;XML;validation;modules and interfaces
507673
Probabilistic congestion control for non-adaptable flows.
In this paper we present a TCP-friendly congestion control scheme for non-adaptable flows. The main characteristic of these flows is that their data rate is determined by an application and cannot be adapted to the current congestion situation of the network. Typical examples of non-adaptable flows are those produced b...
Introduction C ONGESTION control is a vital element of computer networks such as the Internet. It has been widely discussed in the literature { and experienced in reality { that the lack of appropriate congestion control mechanisms will lead to undesirable situations such as a congestion collapse [1]. Under such condit...
TCP-friendliness;non-adaptable flows;congestion control
507677
The design of a transport protocol for on-demand graphical rendering.
In recent years there have been significant advances in 3D scanning technologies that allow the creation of meshes with hundreds of millions of polygons. A number of algorithms have been proposed for the display of such large models. These advances, coupled with the steady growth in the speed of network links, have giv...
INTRODUCTION With the enormous increase in computing power of today's home computers, it is now possible for complex three-dimensional models to be used in home applications. The growth of the Internet introduces the possibility of using such three-dimensional models on websites and online applications. The size of the...
streaming;3-D models;partial order;partial reliability;transport protocol
507680
Impact of link failures on VoIP performance.
We use active and passive traffic measurements to identify the issues involved in the deployment of a voice service over a tier-1 IP backbone network. Our findings indicate that no specific handling of voice packets (i.e. QoS differentiation) is needed in the current backbone but new protocols and mechanisms need to be...
INTRODUCTION Recently, tier-1 Internet Service Providers (ISPs) have shown an ever increasing interest in providing voice and telephone services over their current Internet infrastructures. Voice-over-IP (VoIP) appears to be a very cost effective solution to provide alternative services to the traditional telephone net...
traffic measurements;routing protocols
507688
Topology-aware overlay networks for group communication.
We propose an application level multicast approach, Topology Aware Grouping (TAG), which exploits underlying network topology information to build efficient overlay networks among multicast group members. TAG uses information about path overlap among members to construct a tree that reduces the overlay relative delay p...
INTRODUCTION A variety of issues, both technical and commercial, have hampered the widespread deployment of IP multicast in the global Internet [14, 15]. Application-level multicast approaches using over- Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted with...
routing;overlay networks;application level multicast;topology;network
507695
Distributing streaming media content using cooperative networking.
In this paper, we discuss the problem of distributing streaming media content, both live and on-demand, to a large number of hosts in a scalable way. Our work is set in the context of the traditional client-server framework. Specifically, we consider the problem that arises when the server is overwhelmed by the volume ...
INTRODUCTION There has been much work in recent years on the topic of content distribution. This work has largely fallen into two cat- egories: (a) infrastructure-based content distribution, and (b) peer-to-peer content distribution. An infrastructure-based content distribution network (CDN) (e.g., Akamai) complements ...
content distribution networks;multiple description coding;peer-to-peer networks;streaming media
507723
A cryptographic solution to implement access control in a hierarchy and more.
The need for access control in a hierarchy arises in several different contexts. One such context is managing the information of an organization where the users are divided into different security classes depending on who has access to what. Several cryptographic solutions have been proposed to address this problem ---...
Figure 1: Enterprise Wide Personnel Hierarchy 2. RELATED WORK A number of works [1, 2, 6, 9, 12, 14, 18, 23] relating to access control in a hierarchy have been proposed. In almost all these works, there is a relationship between the key assigned to a node and those assigned to its children. The difference between the...
access control;cryptography;hierarchy
508173
Computational paradigms and protection.
We investigate how protection requirements may be specified and implemented using the imperative, availability and coercion paradigms. Conventional protection mechanisms generally follow the imperative paradigm, requiring explicit and often centralized control over the sequencing and the mediation of security critical ...
INTRODUCTION The sequencing of operations in a computation may be classified in terms of three fundamental paradigms. In the traditional imperative paradigm, the programmer explicitly determines the sequencing constraints of operations; in the availability paradigm, the sequencing of operations depends only on the avai...
protection mechanisms;condensed graphs;functional and dataflow programming;security models;imperative
508810
A fault-tolerant directory service for mobile agents based on forwarding pointers.
A reliable communication layer is an essential component of a mobile agent system. We present a new fault-tolerant directory service for mobile agents, which can be used to route messages to them. The directory service, based on a technique of forwarding pointers, introduces some redundancy in order to ensure resilienc...
INTRODUCTION Mobile agents have emerged as a major programming paradigm for structuring distributed applications [3, 5]. For in- stance, the magnitude project [13] investigates the use of mobile agents as intermediary entities capable of negotiating access to information resources on behalf of mobile users. Several imp...
mobile agents;distributed directory service;fault tolerance
508845
Proxy-based security protocols in networked mobile devices.
We describe a resource discovery and communication system designed for security and privacy. All objects in the system, e.g., appliances, wearable gadgets, software agents, and users have associated trusted software proxies that either run on the appliance hardware or on a trusted computer. We describe how security and...
INTRODUCTION Attaining the goals of ubiquitous and pervasive computing [6, 2] is becoming more and more feasible as the number of computing devices in the world increases rapidly. How- ever, there are still signicant hurdles to overcome when This work was funded by Acer Inc., Delta Electronics Inc., Research Center, an...
protocol;mobile device;ubiquitous;authorization;certificate;wireless;certificate chain discovery;certificate chain;proxy;security;pervasive
508854
A comprehensive model for arbitrary result extraction.
Within the realms of workflow management and grid computing, scheduling of distributed services is a central issue. Most schedulers balance time and cost to fit within a client's budget, while accepting explicit data dependencies between services as the best resolution for scheduling. Results are extracted from one ser...
INTRODUCTION 1.1 Traditional RPCs and asynchronous extraction We address the problem of obtaining results from any of multiple computational servers in response to requests made by a client program. The simplest form of result extraction is the traditional synchronous remote procedure call (RPC). Parameters are passed ...
partial;result extraction;scheduling;progressive;CHARMS
509092
Making sparse Gaussian elimination scalable by static pivoting.
We propose several techniques as alternatives to partial pivoting to stabilize sparse Gaussian elimination. From numerical experiments we demonstrate that for a wide range of problems the new method is as stable as partial pivoting. The main advantage of the new method over partial pivoting is that it permits a priori ...
Introduction In our earlier work [8, 9, 22], we developed new algorithms to solve unsymmetric sparse linear systems using Gaussian elimination with partial pivoting (GEPP). The new algorithms are highly efficient on workstations with deep memory hierarchies and shared memory parallel machines with a modest number of pr...
MPI;static pivoting;iterative refinement;2-D matrix decomposition;sparse unsymmetric linear systems
509094
Tuning Strassen''s matrix multiplication for memory efficiency.
Strassen's algorithm for matrix multiplication gains its lower arithmetic complexity at the expense of reduced locality of reference, which makes it challenging to implement the algorithm efficiently on a modern machine with a hierarchical memory system. We report on an implementation of this algorithm that uses severa...
Introduction The central role of matrix multiplication as a building block in numerical codes has generated a significant amount of research into techniques for improving the performance of this basic operation. Several of these efforts [3, 6, 12, 13, 14, 19] focus on algorithms whose arithmetic complexity This work su...
matrix multiply;strassen's algorithm;data layout;cache memory
509246
Distributed Memory Parallel Architecture Based on Modular Linear Arrays for 2-D Separable Transforms Computation.
A framework for mapping systematically 2-dimensional (2-D) separable transforms into a parallel architecture consisting of fully pipelined linear array stages is presented. The resulting model architecture is characterized by its generality, high degree of modularity, high throughput, and the exclusive use of distribut...
Introduction Separable transforms play a fundamental role in digital signal and image processing. Nearly every problem in DSP is based on the transformation of a time or space domain signal to alternative spaces better suited for efficient storage, transmission, interpretation or estimation. The most commonly employed ...
VLSI architectures;parallel processing;2-D separable transforms
509251
A High Speed VLSI Architecture for Handwriting Recognition.
This article presents PAPRICA-3, a VLSI-oriented architecture for real-time processing of images and its implementation on HACRE, a high-speed, cascadable, 32-processors VLSI slice. The architecture is based on an array of programmable processing elements with the instruction set tailored to image processing, mathemati...
Introduction Handwriting recognition [1, 2, 3] is a major issue in a wide range of application areas, including mailing address interpretation, document analysis, signature verification and, in particular, bank check processing. Handwritten text recognition has to deal with many problems such as the apparent similarity...
parallel architectures;image processing;handwriting recognition;artificial neural networks;VLSI implementations
509594
The effects of communication parameters on end performance of shared virtual memory clusters.
Recently there has been a lot of effort in providing cost-effective Shared Memory systems by employing software only solutions on clusters of high-end workstations coupled with high-bandwidth, low-latency commodity networks. Much of the work so far has focused on improving protocols, and there has been some work on res...
Introduction With the success of hardware cache-coherent distributed shared memory (DSM), a lot of effort has been made to support the programming model of a coherent shared address space using commodity- oriented communication architectures in addition to commodity nodes. The techniques for the communication architect...
distributed memory;bandwidth;latency;network occupancy;shared memory;host overhead;communication parameters;interrupt cost;clustering
509603
Compiling parallel code for sparse matrix applications.
We have developed a framework based on relational algebra for compiling efficient sparse matrix code from dense DO-ANY loops and a specification of the representation of the sparse matrix. In this paper, we show how this framework can be used to generate parallel code, and present experimental data that demonstrates th...
Introduction Sparse matrix computations are ubiquitous in computational science. However, the development of high-performance software for sparse matrix computations is a tedious and error-prone task, for two reasons. First, there is no standard way of storing sparse matri- ces, since a variety of formats are used to a...
sparse matrix computations;parallelizing compilers
509605
Compiling stencils in high performance Fortran.
For many Fortran90 and HPF programs performing dense matrix computations, the main computational portion of the program belongs to a class of kernels known as stencils. Stencil computations are commonly used in solving partial differential equations, image processing, and geometric modeling. The efficient handling of s...
Introduction High-Performance Fortran (HPF)[14], an extension of Fortran90, has attracted considerable attention as a promising language for writing portable parallel programs. HPF offers a simple programming model shielding programmers from the intricacies of concurrent programming and managing distributed data. Progr...
stencil compilation;high performance Fortran;communication unioning;statement partitioning;shift optimization
509611
Portable performance of data parallel languages.
A portable program executes on different platforms and yields consistent performance. With the focus on portability, this paper presents an in-depth study of the performance of three NAS benchmarks (EP, MG, FT) compiled with three commercial HPF compilers (APR, PGI, IBM) on the IBM SP2. Each benchmark is evaluated in t...
Introduction Portability is defined as the ability to use the same program on different platforms and to achieve consistent performance. Developing a parallel program that is both portable and scalable is well recognized as a challenging endeavor. However, the difficulty is not necessarily an intrinsic property of para...
MPI;performance model;NAS;HPF;ZPL;data paraller language
509627
Massively parallel simulations of diffusion in dense polymeric structures.
An original computational technique to generate close-to-equilibrium dense polymeric structures is proposed. Diffusion of small gases are studied on the equilibrated structures using massively parallel molecular dynamics simulations running on the Intel Teraflops (9216 Pentium Pro processors) and Intel Paragon (1840 pr...
Introduction Many technological processes depend on the design of polymers with desired permeation characteristics of small molecules. Examples include gas separation with polymeric membranes, food packaging, and encapsulant of electronic components in polymers that act as barriers to atmospheric gases and moisture. To...
gas diffusion;teraflop;molecular builder;molecular dynamics;polymer
509641
A scalable mark-sweep garbage collector on large-scale shared-memory machines.
This work describes implementation of a mark-sweep garbage collector (GC) for shared-memory machines and reports its performance. It is a simple ''parallel'' collector in which all processors cooperatively traverse objects in the global shared heap. The collector stops the application program during a collection and as...
Introduction Shared-memory architecture is attractive platform for implementation of general-purpose parallel programming languages that support irregular, pointer-based data structures [4, 20]. The recent progress in scalable shared-memory technologies is also making these architectures attractive for high-performance...
scalability;shared-memory machine;parallel algorithm;dynamic load balancing;garbage collection
509644
Loop re-ordering and pre-fetching at run-time.
The order in which loop iterations are executed can have a large impact on the number of cache misses that an applications takes. A new loop order that preserves the semantics of the old order but has a better cache data re-use, improves the performance of that application. Several compiler techniques exist to transfor...
Introduction Despite rapid increases in CPU performance, the primary obstacles to achieving higher performance in current processor organizations remain control and data hazards. An estimate [5] shows that the performance of single-chip microprocessors are improving at a rate of 80% annually, while DRAM speeds are impr...
systolic arrays;coarse-grain dataflow;temporal locality;dependence-driven;data locality;run-time systems;loop transformations
509647
Performance characteristics of gang scheduling in multiprogrammed environments.
Gang scheduling provides both space-slicing and time-slicing of computer resources for parallel programs. Each thread of execution from a parallel job is concurrently scheduled on an independent processor in order to achieve an optimal level of program performance. Time-slicing of parallel jobs provides for better over...
Introduction Interest in parallel computers has been propelled by both the economics of commodity priced microprocessors and a growth rate in computational requirements exceeding processor speed increases. The symmetric multiprocessor (SMP) and massively parallel processor (MPP) architectures have proven quite popular,...
multiprogramming;gang scheduling;time-slicing;parallel system;space-slicing;scheduling
509649
A common data management infrastructure for adaptive algorithms for PDE solutions.
This paper presents the design, development and application of a computational infrastructure to support the implementation of parallel adaptive algorithms for the solution of sets of partial differential equations. The infrastructure is separated into multiple layers of abstraction. This paper is primarily concerned w...
Introduction This paper describes the design and implementation of a common computational infrastructure to support parallel adaptive solutions of partial differential equations. The motivations for this research are: 1. Adaptive methods will be utilized for the solution of almost all very large-scale scientific and en...
fast multipole methods;problem solving environment;adaptive mesh-refinement;HP-adaptive finite elements;parallel adaptive algorithm;distributed dynamic data structures
509912
New results on monotone dualization and generating hypergraph transversals.
This paper considers the problem of dualizing a monotone CNF (equivalently, computing all minimal transversals of a hypergraph), whose associated decision problem is a prominent open problem in NP-completeness. We present a number of new polynomial time resp. output-polynomial time results for significant cases, which ...
INTRODUCTION # Part of the work carried out while visiting TU Wien. Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for pro-t or commercial advantage and that copies bear this notice and the full ...
hypergraph acyclicity;dualization;treewidth;limited nondeterminism;output-polynomial algorithms;transversal computation;combinatorial enumeration
510729
Multicast Video-on-Demand services.
The server's storage I/O and network I/O bandwidths are the main bottleneck of VoD service. Multicast offers an efficient means of distributing a video program to multiple clients, thus greatly improving the VoD performance. However, there are many problems to overcome before development of multicast VoD systems. This ...
INTRODUCTION A typical Video-on-Demand (VoD) service allows remote users to play back any one of a large collection of videos at any time. Typically, these video les are stored in a set of central video servers, and distributed through high-speed communication networks to geographically-dispersed clients. Upon receivin...
Video-on-Demand VoD;VCR-like interactivity;scheduling;multicast;Quality-of-Service QoS
510775
On securely scheduling a meeting.
When people want to schedule a meeting, their agendas must be compared to find a time suitable for all participants. At the same time, people want to keep their agendas private. This paper presents several approaches which intend to solve this contradiction. A custom (---) made protocol for secure meeting scheduling an...
INTRODUCTION When negotiating meetings, the participants look up, communicate and process information about each other's agendas trying to nd a moment when they are all free to attend the meeting. Due to the private nature of a person's schedule, as little as possible should be revealed to any other party during that n...
meeting scheduling;secure distributed computation;mobile agents
510800
Extended description techniques for security engineering.
There is a strong demand for techniques to aid development and modelling of security critical systems. Based on general security evaluation criteria, we show how to extend the system structure diagrams of the CASE tool AutoFocus (which are related to UML-RT collaboration diagrams) to allow modelling of security critica...
INTRODUCTION In developing distributed systems-in particular applications that communicate over open networks like the Internet-security is an extremely important issue. Many customers are reluctant to take part in electronic business, confirmed by recent attacks on well-known portal sites or cases of credit card fraud...
security patterns;UML-RT;security properties;formal methods;security engineering;autofocus;requirements engineering;graphical description techniques;design patterns;CASE;software engineering
510866
Write barrier removal by static analysis.
We present a set of static analyses for removing write barriers in programs that use generational garbage collection. To our knowledge, these are the first analyses for this purpose. Our Intraprocedural analysis uses a flow-sensitive pointer analysis to locate variables that must point to the most recently allocated ob...
INTRODUCTION Generational garbage collectors have become the memory management alternative of choice for many safe languages. The basic idea behind generational collection is to segregate objects into dierent generations based on their age. Gen- This research was supported in part by an NSF Fellowship, DARPA Contract F...
program analysis;generational garbage collection;write barriers;pointer analysis
510867
Efficient global register allocation for minimizing energy consumption.
Data referencing during program execution can be a significant source of energy consumption especially for data-intensive programs. In this paper, we propose an approach to minimize such energy consumption by allocating data to proper registers and memory. Through careful analysis of boundary conditions between consecu...
Introduction Today's high demand of portable electronic products makes low energy consumption as important as high speed and small area in computer system design. Even for non-portable high performance systems, lower power consumption design helps to decrease packing and cooling cost and increase the reliability of the...
low energy;register allocation
510962
How to Choose Secret Parameters for RSA-Type Cryptosystems over Elliptic Curves.
Recently, and contrary to the common belief, Rivest and Silverman argued that the use of strong primes is unnecessary in the RSA cryptosystem. This paper analyzes how valid this assertion is for RSA-type cryptosystems over elliptic curves. The analysis is more difficult because the underlying groups are not always cycl...
Introduction The theory of elliptic curves has been extensively studied for the last 90 years. In 1985, Koblitz and Miller independently suggested their use in cryptography [9, 19]. After this breakthrough, elliptic curve-based analogues of RSA cryptosystem were proposed [10, 4]. RSA-type systems belong to the family o...
RSA-type cryptosystems;strong primes;cycling attacks;elliptic curves