name stringlengths 5 6 | title stringlengths 8 144 | abstract stringlengths 0 2.68k | fulltext stringlengths 1.78k 95k | keywords stringlengths 22 532 |
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316485 | Homotopy of Non-Modular Partitions and the Whitehouse Module. | We present a class of subposets of the partition lattice n with the following property: The order complex is homotopy equivalent to the order complex of n 1, and the Sn-module structure of the homology coincides with a recently discovered lifting of the Sn 1-action on the homology of n 1. This is the Whitehouse repre... | Introduction
In this paper we consider subposets of the partition lattice \Pi n obtained by
removing various modular elements. Recall that \Pi n is the lattice of set partitions of
an n-element set, ordered by refinement. We say a block of a partition is nontrivial
if it consists of more than one element. The modular e... | group representation;poset;homology;homotopy;set partition |
316521 | Modifying a Sparse Cholesky Factorization. | Given a sparse symmetric positive definite matrix ${\bf AA}^{\sf T}$ and an associated sparse Cholesky factorization ${\bf LDL}^{\sf T}$ or ${\bf LL}^{\sf T}$, we develop sparse techniques for obtaining the new factorization associated with either adding a column to ${\bf A}$ or deleting a column from ${\bf A}$. Our te... | Introduction
This paper presents a method for updating and downdating the sparse Cholesky
factorization LL T of the matrix AA T , where A is m by n. More precisely, we evaluate
the Cholesky factorization of AA T either oe is +1 (corresponding to
an update) and w is arbitrary, or oe is \Gamma1 (corresponding to a downda... | numerical linear algebra;matrix updates;cholesky factorization;sparse matrices;mathematical software;direct methods |
316530 | Decay Rates of the Inverse of Nonsymmetric Tridiagonal and Band Matrices. | It is well known that the inverse of an irreducible nonsingular symmetric tridiagonal matrix is given by two sequences of real numbers, {ui} and {vi}, such that similar result holds for nonsymmetric matrices A. There the inverse can be described by four sequences {ui},{vi}, {xi},$ and {vi} with u xiyi. Here we charact... | Introduction
In many mathematical problems which gives rise to a linear system of equations the
system matrix is tridiagonal or block tridiagonal. For example the numerical solution
of partial differential equations mostly leads to tridiagonal (one dimensional
problems) and block tridiagonal (higher dimensional problem... | inverses of tridiagonal matrices;tridiagonal matrices;decay rates |
316687 | loops in almost linear time. | Loop identification is an essential step in performing various loop optimizations and transformations. The classical algorithm for identifying loops is Tarjan's interval-finding algorithm, which is restricted to reducible graphs. More recently, serveral people have proposed extensions to Tarjan's algortihm to deal with... | INTRODUCTION
Loop identification is an interesting control flow analysis problem that has several
applications. The classical algorithm for identifying loops is Tarjan's interval
finding algorithm [Tarjan 1974], which is restricted to reducible graphs. More re-
cently, several people have proposed extensions to Tarjan'... | irreducible flowgraphs;loops |
317048 | Similarity Measures. | AbstractWith complex multimedia data, wesee the emergence of database systems in which the fundamental operation is similarity assessment. Before database issues can be addressed, it is necessary to give a definition of similarity as an operation. In this paper, we develop a similarity measure, based on fuzzy logic, th... | Introduction
Comparing two images, or an image and a model, is the fundamental operation for many Visual
Information Retrieval systems. In most systems of interest, a simple pixel-by-pixel comparison
won't do: the difference that we determine must bear some correlation with the perceptual difference
of the two images, ... | image distances;content-based retrieval;similarity measures;image databases;perceptual similarity |
317993 | Efficient admission control algorithms for multimedia servers. | In this paper, we have proposed efficient admission control algorithms for multimedia storage servers that are providers of variable-bit-rate media streams. The proposed schemes are based on a slicing technique and use aggressive methods for admission control. We have developed two types of admission control schemes: <... | Introduction
Recent developments in computer systems and high speed networks have propelled
the research on multimedia systems. A multimedia system requires the integration of
communication, storage, retrieval, and presentation mechanisms for diverse data types
including text, images, audio, and video to provide a sing... | interval estimation algorithm;quality of service;multimedia storage server;admission control;future-Max algorithm |
317995 | An effective admission control mechanism for variable-bit-rate video streams. | For admission control in real-time multimedia systems, buffer space, disk bandwidth and network bandwidth must be considered. The CBR-based mechanisms do not use system resources effectively, since media data is usually encoded with VBR compression techniques. We propose an admission control mechanism based on a VBR da... | Introduction
Multimedia systems like VOD (Video-On-Demand) systems require considerable resources
and have tight real-time constraints. Multimedia data to be sent to clients must be read from
disk to memory buffers before the actual transmission, and thus the maximum number of
clients that the system can support depend... | video-on-demand systems;disk scheduling;buffer management;admission control;variable bit rate |
318117 | Using Traffic Regulation to Meet End-to-End Deadlines in ATM Networks. | AbstractThis paper considers the support of hard real-time connections in ATM networks. In an ATM network, a set of hard real-time connections can be admitted only if the worst case end-to-end delays of cells belonging to individual connections are less than their deadlines. There are several approaches to managing the... | Introduction
There is a growing interest in the application of ATM networks for distributed Hard Real-Time
(HRT) systems. In a distributed HRT system, tasks are executed at different nodes and communicate
amongst themselves by exchanging messages. The messages exchanged by time-critical
tasks have to be delivered by ce... | network delay analysis;ATM network;hard real-time communication;traffic regulation |
318943 | Efficient points-to analysis for whole-program analysis. | To function on programs written in languages such as C that make extensive use of pointers, automated software engineering tools require safe alias information. Existing alias-analysis techniques that are sufficiently efficient for analysis on large software systems may provide alias information that is too imprecise f... | Introduction
Many automated tools have been proposed for use in software engineering. To
function on programs written in languages such as C that make extensive use of
pointers, these tools require alias information that determines the sets of memory
locations accessed by dereferences of pointer variables. Atkinson and... | pointer analysis;aliasing analysis;points-to graph |
319249 | Classifying Facial Actions. | AbstractThe Facial Action Coding System (FACS) [23] is an objective method for quantifying facial movement in terms of component actions. This system is widely used in behavioral investigations of emotion, cognitive processes, and social interaction. The coding is presently performed by highly trained human experts. Th... | Introduction
Facial expressions provide information not only about affective state, but also about cognitive activity,
temperament and personality, truthfulness, and psychopathology. The Facial Action Coding System
[23] is the leading method for measuring facial movement in behavioral science. FACS is currently perform... | principal component analysis;gabor wavelets;Facial Action Coding System;facial expression recognition;independent component analysis;computer vision |
319259 | Alignment Using Distributions of Local Geometric Properties. | AbstractWe describe a framework for aligning images without needing to establish explicit feature correspondences. We assume that the geometry between the two images can be adequately described by an affine transformation and develop a framework that uses the statistical distribution of geometric properties of image co... | Introduction
Image alignment (variously known as registration, positioning etc.) amounts to establishing a common
frame of reference for a set of images. Alignment is an essential step for many tasks such
as data fusion, change detection, pose recovery etc. and has been widely investigated in various
contexts. A good s... | geometric properties;statistical distributions;pose estimation;correspondenceless image alignment |
319267 | Line-Based Face Recognition under Varying Pose. | AbstractMuch research in human face recognition involves fronto-parallel face images, constrained rotations in and out of the plane, and operates under strict imaging conditions such as controlled illumination and limited facial expressions. Face recognition using multiple views in the viewing sphere is a more difficul... | Introduction
Automated face recognition (AFR) has attracted much interest over the past
few years. Such interest has been motivated by the growth in applications in
many areas including, face identification in law enforcement and forensics,
user authentication in building access or automatic transaction machines,
index... | face recognition;line-based algorithm;real-time performance;varying pose;classification accuracy |
319335 | Transparent distributed processing for rendering. | Rendering, in particular the computation of global illumination, uses computationally very demanding algorithms. As a consequence many researchers have looked into speeding up the computation by distributing it over a number of computational units. However, in almost all cases did they completely redesign the relevant ... | INTRODUCTION
Usually, distributed algorithms differ considerably from their non-distributed
versions. In order to achieve optimal performance, care-
Am Weichselgarten 9, 91058 Erlangen, Germany
Email: kipfer@informatik.uni-erlangen.de
y Gates Building 364-3B, Stanford, CA, 94306, USA
ful attention has be paid to issues... | distributed processing;lighting networks;design pattern;parallel processing;object-oriented design;global illumination |
319350 | Specificational functions. | Mathematics supplies us with various operators for creating functions from relations, sets, known functions, and so on. Function inversion is a simple example. These operations are useful in specifying programs. However, many of them have strong constraints on their arguments to ensure that the result is indeed a funct... | INTRODUCTION
The square function on the integers, defined by sqr -
z), is not traditionally
regarded as having a well-defined inverse, because it is neither injective
nor surjective. Suppose, however, we were to broaden our definition of functions
so that the inverse of sqr, call it sqrt, is indeed a function. We might... | function;refinement calculus;nondeterminacy;logic;expression |
319359 | Efficient compression of non-manifold polygonal meshes. | We present a method for compressing non-manifold polygonal meshes, i.e. polygonal meshes with singularities, which occur very frequently in the real-world. Most efficient polygonal compression methods currently available are restricted to a manifold mesh: they require a conversion process, and fail to retrieve the orig... | Table
To encode the information necessary to cluster some
vertices and recover the polygon-vertices incidence
relationship of the original model, one simple approach
(which we are not using, but explain for comparison)
would be to transmit a table such as this, with one row
per cluster. This table relates to the exampl... | geometry compression;stitching;non-manifold;polygonal mesh |
319424 | LOD-sprite technique for accelerated terrain rendering. | We present a new rendering technique, termed LOD-sprite rendering, which uses a combination of a level-of-detail (LOD) representation of the scene together with reusing image sprites (previously rendered images). Our primary application is accelerating terrain rendering. The LOD-sprite technique renders an initial fram... | INTRODUCTION
As scene geometry becomes complex (into the millions of poly-
gons), even the most advanced rendering hardware cannot provide
interactive rates. Current satellite imaging technology provides terrain
datasets which are well beyond this level of complexity. This
presents two problems for real-time systems: 1... | virtual reality;terrain rendering;texture mapping;virtual environments;acceleration techniques;image-based modeling rendering;level of detail;multi-resolution |
319435 | High performance presence-accelerated ray casting. | We present a novel presence acceleration for volumetric ray casting. A highly accurate estimation for object presence is obtained by projecting all grid cells associated with the object boundary on the image plane. Memory space and access time are reduced by run-length encoding of the boundary cells, while boundary cel... | Introduction
An effective approach to achieve high frame rates for volume rendering
is to parallelize a fast rendering algorithm that relies on some
algorithmic optimizations [1, 2, 3, 4]. Two requirements must be
met for this approach to achieve interactive rendering. First, the
serial volume rendering algorithm must ... | run-length encoding;projection template;presence acceleration;parallel processing;volume rendering;multiresolution volumes;interactive classification |
319725 | Anonymous authentication with subset queries (extended abstract). | We develop new schemes for anonymous authentication that support identity escrow. Our protocols also allow a prover to demonstrate membership in an arbitrary subset of users; key revocation is an important special case of this feature. Using the Fiat-Shamir heuristic, our interactive authentication protocols yield new ... | Introduction
Consider an o-ce building where each employee is given
a smartcard for opening the front door to the building.
Employees are often concerned that their movements in
and out of the building are being recorded. Consequently
it is desirable that the authentication protocol carried out
between the smartcard (p... | group signature;identity escrow;anonymous authentication |
319961 | Automatically extracting structure and data from business reports. | A considerable amount of clean semistructured data is internally available to companies in the form of business reports. However, business reports are untapped for data mining, data warehousing, and querying because they are not in relational form. Business reports have a regular structure that can be reconstructed. We... | Introduction
A considerable amount of clean semistructured data is available to companies through internal
business reports created during periodic data processing. Business reports provide data for
monitoring account balances, inventory levels, transaction status, current production status,
etc. Although the subject m... | automatic wrapper generation;regular expressions;report structure;data and information extraction;business reports |
319974 | Requirement-based data cube schema design. | On-line analytical processing (OLAP) requires efficient processing of complex decision support queries over very large databases. It is well accepted that pre-computed data cubes can help reduce the response time of such queries dramatically. A very important design issue of an efficient OLAP system is therefore the ch... | Introduction
With wide acceptance of the data warehousing tech-
nology, corporations are building their decision support
systems (DSS) on large data warehouses. Many of
these DSS's have on-line characteristics and are termed
On-line Analytical Processing (OLAP) systems. Different
from the conventional database applicat... | data cubes;OLAP;DSS;data cube schema design |
320020 | Updates and view maintenance in soft real-time database systems. | A database system contains base data items which record and model a physical, real world environment. For better decision support, base data items are summarized and correlated to derive views. These base data and views are accessed by application transactions to generate the ultimate actions taken by the system. As th... | Introduction
A real-time database system (RTDB) is often employed in a dynamic environment to monitor
the status of real-world objects and to discover the occurrences of "interesting" events [15, 10,
2, 3]. As an example, a program trading application monitors the prices of various stocks,
financial instruments, and cu... | real-time database;temporal consistency;transaction scheduling;updates;view maintenance |
320215 | Randomized fully dynamic graph algorithms with polylogarithmic time per operation. | This paper solves a longstanding open problem in fully dynamic algorithms: We present the first fully dynamic algorithms that maintain connectivity, bipartiteness, and approximate minimum spanning trees in polylogarithmic time per edge insertion or deletion. The algorithms are designed using a new dynamic technique tha... | Introduction
In many areas of computer science, graph algorithms play an important role: Problems modeled
by graphs are solved by computing a property of the graph. If the underlying problem instance
changes incrementally, algorithms are needed that quickly compute the property in the modified
graph. Algorithms that ma... | dynamic graph algorithms;connectivity |
320249 | Optimization of queries with user-defined predicates. | Relational databases provide the ability to store user-defined functions and predicates which can be invoked in SQL queries. When evaluation of a user-defined predicate is relatively expensive, the traditional method of evaluating predicates as early as possible is no longer a sound heuristic. There are two previous ap... | Introduction
In order to efficiently execute complex database appli-
cations, many major relational database vendors provide
the ability to define and store user-defined func-
tions. Such functions can be invoked in SQL queries
and make it easier for developers to implement their
applications. However, such extensions ... | query optimization;user-defined predicates;dynamic programming |
320310 | A distributed algorithm for graphic objects replication in real-time group editors. | Real-time collaborative editing systems are groupware systems that allow multiple users to edit the same document at the same time from multiple sites. A specific type of collaborative editing system is the object-based collaborative graphics editing system. One of the major challenge in building such systems is to sol... | Introduction
People collaborate to solve problems which would otherwise
be difficult or impossible for individuals. However,
group work can become unproductive and expensive [8]. For
these reasons, many researchers have been conducting studies
on how to effectively support group work [3]. Computer-Supported
Cooperative... | distributed computing;concurrency control;collaborative editing;graphics editing;consistency maintenance |
320322 | Use of Virtual Science Park resource rooms to support group work in a learning environment. | This paper presents a detailed evaluation on the acceptability of a range of synchronous and asynchronous collaborative tools provided within the Virtual Science Park (VSP) for group work in a learning environment. In this study, the VSP was used to provide a web-based 'Resource Room' adopting the familiar 'folder' met... | INTRODUCTION
The aim of this paper is to explore the effective use of
a range of groupware tools provided in the Virtual
Science Park (VSP) for group work in a potentially
distributed learning environment. It examines the level
of support being offered to students in order to gain
access to tutors and for students to w... | evaluation;common information space;co-operative learning;collaborative tools;Virtual Science Park |
320390 | A problem-oriented analysis of basic UML static requirements modeling concepts. | The Unified Modeling Language (UML) is a standard modeling language in which some of the best object-oriented (OO) modeling experiences are embedded. In this paper we illustrate the role formal specification techniques can play in developing a precise semantics for the UML. We present a precise characterization of requ... | INTRODUCTION
The Unified Modeling Language (UML) [10] is a standard
language for modeling complex systems from a variety
of views using object-oriented (OO) concepts. The
effectiveness of the UML as a standard is predicated,
among other things, on there being a clear, precise, and
pragmatic semantics for its notations.... | UML;requirements class diagrams;precise semantics |
320391 | A language for specifying recursive traversals of object structures. | We present a domain-specific language for specifying recursive traversals of object structures, for use with the visitor pattern. Traversals are traditionally specified as iterations, forcing the programmer to adopt an imperative style, or are hard-coded into the program or visitor. Our proposal allows a number of prob... | Introduction
The visitor pattern [GHJV95] allows a programmer to write
behavior that traverses an object structure without embedding
assumptions about the structure into the computational
code. This is a result of separating navigational code
from code that performs the computation. In most versions
of the visitor patt... | recursive programming;separation of concerns;visitor pattern |
320425 | Age-based garbage collection. | Modern generational garbage collectors look for garbage among the young objects, because they have high mortality; however, these objects include the very youngest objects, which clearly are still live. We introduce new garbage collection algorithms, called age-based, some of which postpone consideration of the younges... | INTRODUCTION
Dynamic memory management (management of heap-allocated ob-
jects) using garbage collection has become part of mainstream computing
with the advent of Java, a language that uses and requires
This work is supported in part by NSF grant IRI-9632284, and by
gifts from Compaq Corp., Sun Microsystems, and Hewle... | object behavior;write barrier;garbage collection;generational and copy collection |
320426 | Software-Directed Register Deallocation for Simultaneous Multithreaded Processors. | AbstractThis paper proposes and evaluates software techniques that increase register file utilization for simultaneous multithreading (SMT) processors. SMT processors require large register files to hold multiple thread contexts that can issue instructions out of order every cycle. By supporting better interthread shar... | Introduction
Simultaneous multithreading (SMT) is a high-performance architectural technique that
substantially improves processor performance by executing multiple instructions from multiple
threads every cycle. By dynamically sharing processor resources among threads, SMT increases
functional unit utilization, thereb... | simultaneous multithreading;multithreaded architecture;architecture;register file |
322530 | Inductive analysis of the Internet protocol TLS. | Internet browsers use security protocols to protect sensitive messages. An inductive analysis of TLS (a descendant of SSL 3.0) has been performed using the theorem prover Isabelle. Proofs are based on higher-order logic and make no assumptions concerning beliefs of finiteness. All the obvious security goals can be prov... | INTRODUCTION
Internet commerce requires secure communications. To order goods, a customer
typically sends credit card details. To order life insurance, the customer might
have to supply condential personal data. Internet users would like to know that
such information is safe from eavesdropping or alteration.
Many Web b... | TLS;inductive method;proof tools;isabelle;authentication |
322588 | Constraint cascading style sheets for the Web. | Cascading Style Sheets have been introduced by the W3C as a mechanism for controlling the appearance of HTML documents. In this paper, we demonstrate how constraints provide a powerful unifying formalism for declaratively understanding and specifying style sheets for web documents. With constraints we can naturally and... | INTRODUCTION
Since the inception of the Web there has been tension between
the "structuralists" and the "designers." On one hand,
structuralists believe that a Web document should consist
only of the content itself and tags indicating the logical structure
of the document, with the browser free to determine the
documen... | constraints;style sheets;CSS;page layout;CCSS;cascading style sheets;world wide web;HTML;cassowary |
322863 | An Efficient Fault-Tolerant Multicast Routing Protocol with Core-Based Tree Techniques. | AbstractIn this paper, we design and analyze an efficient fault-tolerant multicast routing protocol. Reliable multicast communication is critical for the success of many Internet applications. Multicast routing protocols with core-based tree techniques (CBT) have been widely used because of their scalability and simpli... | Introduction
Reliable multicast communication is critical for the
success of many applications such as video/audio-
broadcasting, resource discovery, server location, etc.
Recently, these applications have become increasingly
popular due to the availability of the Internet.
In general, there are two approaches for mult... | multicast routing;core-based trees;fault tolerance |
323001 | Matching Hierarchical Structures Using Association Graphs. | AbstractIt is well-known that the problem of matching two relational structures can be posed as an equivalent problem of finding a maximal clique in a (derived) association graph. However, it is not clear how to apply this approach to computer vision problems where the graphs are hierarchically organized, i.e., are tre... | where jCj denotes the cardinality of C.
Now, consider the following quadratic function
where A ??aij? is the adjacency matrix of G, i.e., the n n
symmetric matrix defined as
0; otherwise:
A point x 2 Sn is said to be a global maximizer of f in Sn if
f?x?f?x?, for all x 2 Sn. It is said to be a local maximizer
if there... | shape recognition;replicator dynamical systems;maximal subtree isomorphisms;shock trees;association graphs;maximal cliques |
323223 | Analytical Modeling of Set-Associative Cache Behavior. | AbstractCache behavior is complex and inherently unstable, yet it is a critical factor affecting program performance. A method of evaluating cache performance is required, both to give quantitative predictions of miss-ratio and information to guide optimization of cache use. Traditional cache simulation gives accurate ... | Introduction
Cache performance is one of the most critical factors affecting the performance of
software, and with memory latency continuing to increase in respect to processor
clock speeds utilizing the cache to its full potential is more and more essential.
Yet cache behavior is extremely difficult to analyze, reflec... | performance evaluation;analytical modeling;data locality;set-associative;cache modeling;cache interference |
323323 | Leading-One Prediction with Concurrent Position Correction. | AbstractThis paper describes the design of a leading-one prediction (LOP) logic for floating-point addition with an exact determination of the shift amount for normalization of the adder result. Leading-one prediction is a technique to calculate the number of leading zeros of the result in parallel with the addition. H... | INTRODUCTION
Leading-one prediction is used in floating-point adders to eliminate the delay of the
determination of the leading-one position of the adder output from the critical path. This
determination is needed to perform the normalization of the result. Since the latency
of floating-point addition is significant in... | leading-one prediction;floating-point addition;normalization |
323337 | Parallel Complexity of Numerically Accurate Linear System Solvers. | We prove a number of negative results about practical (i.e., work efficient and numerically accurate) algorithms for computing the main matrix factorizations. In particular, we prove that the popular Householder and Givens methods for computing the QR decomposition are P-complete, and hence presumably inherently sequen... | Introduction
strongly nonsingular
Mauro Leoncini Giovanni Manzini Luciano Margara
August 8, 1997
Parallel Complexity of Numerically Accurate Linear
System Solvers.
This work merges preliminary results presented at ESA '96 and SPAA '97.
Dipartimento di Informatica, Universit'a di Pisa, Corso Italia 40, 56125 Pisa, Italy... | numerical stability;NC algorithms;inherently sequential algorithms;p-complete problems;parallel complexity;matrix factorization |
323803 | Redundant Radix Representations of Rings. | AbstractThis paper presents an analysis of radix representations of elements from general rings; in particular, we study the questions of redundancy and completeness in such representations. Mappings into radix representations, as well as conversions between such, are discussed, in particular where the target system is... | Introduction
Number representations have for long been a central
research topic in the field of computer arithmetic, since
choosing the wrong number system can have detrimental
effects on such aspects of computer design as storage effi-
ciency, accuracy and speed of operation. Designing a number
system amounts to choos... | number system conversion;radix representation of rings;redundancy;computer arithmetic;integer and computer radix number systems |
323812 | Active Management of Data Caches by Exploiting Reuse Information. | AbstractAs microprocessor speeds continue to outpace memory subsystems in speed, minimizing average data access time grows in importance. Multilateral caches afford an opportunity to reduce the average data access time by active management of block allocation and replacement decisions. We evaluate and compare the perfo... | Introduction
Minimizing the average data access time is of paramount importance when designing high-performance
machines. Unfortunately, access time to o-chip memory (measured in processor
clock cycles) has increased dramatically as the disparity between main memory access
Work done while at the University of Michigan.... | reuse information;active management;multilateral cache |
324139 | Purely functional, real-time deques with catenation. | We describe an efficient, purely functional implementation of deques with catenation. In addition to being an intriguing problem in its own right, finding a purely functional implementation of catenable deques is required to add certain sophisticated programming constructs to functional programming languages. Our solut... | Introduction
A persistent data structure is one in which a change to the structure can be made without destroying
the old version, so that all versions of the structure persist and can at least be accessed (the structure
is said to be partially persistent) or even modified (the structure is said to be fully persistent)... | purely functional queues;queue;double-ended queue;purely functional data structures;data structures;stack;catenation;persistent data structures |
324179 | Linear hash functions. | Consider the set H of all linear (or affine) transformations between two vector spaces over a finite field F. We study how good H is as a class of hash functions, namely we consider hashing a set S of size n into a range having the same cardinality n by a randomly chosen function from H and look at the expected... | Introduction
Consider distributing n balls in s buckets, randomly and independently. The resulting distribution
of the balls in the buckets is the object of occupancy theory.
Dep. of Math., Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, Israel and Institute for Advanced
Study, Princeton, NJ 08540. Re... | universal hashing;hashing via linear maps |
324266 | Secrecy by typing in security protocols. | We develop principles and rules for achieving secrecy properties in security protocols. Our approach is based on traditional classification techniques, and extends those techniques to handle concurrent processes that use shared-key cryptography. The rules have the form of typing rules for a basic concurrent language wi... | Introduction
Security is an elusive cocktail with many rare ingredients. For any given security
protocol, one may want properties of integrity, confidentiality, availability, various
forms of anonymity and non-repudiation, and more. Seldom does a protocol
achieve all the properties that its designers intended. Moreover... | cryptographic protocols;process calculi;secrecy properties |
324345 | ARMADA Middleware and Communication Services. | Real-time embedded systems have evolved during the past several decades from small custom-designed digital hardware to large distributed processing systems. As these systems become more complex, their interoperability, evolvability and cost-effectiveness requirements motivate the use of commercial-off-the-shelf compone... | Introduction
ARMADA is a collaborative project between the Real-Time Computing Laboratory (RTCL)
at the University of Michigan and the Honeywell Technology Center. The goal of the
project is to develop and demonstrate an integrated set of communication and middleware
services and tools necessary to realize embedded fau... | fault-tolerant systems;communication protocols;distributed real-time systems |
325396 | A Highly Available Local Leader Election Service. | AbstractWe define the highly available local leader election problem, a generalization of the leader election problem for partitionable systems. We propose a protocol that solves the problem efficiently and give some performance measurements of our implementation. The local leader election service has been proven usefu... | Introduction
T HE leader election problem [1] requires that a unique
leader be elected from a given set of processes. The
problem has been widely studied in the research community
[2], [3], [4], [5], [6]. One reason for this wide interest is
that many distributed protocols need an election protocol
as a sub-protocol. F... | global leader election;local leader election;timed asynchronous systems;partitionable systems |
325398 | Experimenting with Quantitative Evaluation Tools for Monitoring Operational Security. | AbstractThis paper presents the results of an experiment in security evaluation. The system is modeled as a privilege graph that exhibits its security vulnerabilities. Quantitative measures that estimate the effort an attacker might expend to exploit these vulnerabilities to defeat the system security objectives are pr... | Introduction
Security is an increasing worry for most computing system administrators: computing systems
are more and more vital for most companies and organizations, while these systems are
made more and more vulnerable by new user requirements and new services (groupware and
other information sharing facilities; inte... | operational vulnerabilities;quantitative evaluation;privilege graph;security assessment |
325399 | Systematic Formal Verification for Fault-Tolerant Time-Triggered Algorithms. | AbstractMany critical real-time applications are implemented as time-triggered systems. We present a systematic way to derive such time-triggered implementations from algorithms specified as functional programs (in which form their correctness and fault-tolerance properties can be formally and mechanically verified wit... | Introduction
Synchronous systems are distributed computer systems where there are known
upper bounds on the time that it takes nonfaulty processors to perform certain op-
erations, and on the time that it takes for a message sent by one nonfaulty processor
to be received by another. The existence of these bounds simpli... | formal verification;formal methods;time-triggered algorithms;synchronous systems;PVS |
325511 | The Riemann Zeros and Eigenvalue Asymptotics. | Comparison between formulae for the counting functions of the heights tn of the Riemann zeros and of semiclassical quantum eigenvalues En suggests that the tn are eigenvalues of an (unknown) hermitean operator H, obtained by quantizing a classical dynamical system with hamiltonian Hcl. Many features of Hcl are provid... | log x x (x2 1) x log x xImtn
Retn>0
(see section 1.18 of [7]). Here the numbers tn in the oscillatory contributions are
related to the complex Riemann zeros, dened as follows.
Riemann's zeta function, depending on the complex variable s, is dened as
Y X1
ns (Res>1)
and by analytic continuation elsewhere in the s plane.... | number theory;spectral asymptotics |
325700 | A framework for combining analysis and verification. | We present a general framework for combining program verification and program analysis. This framework enhances program analysis because it takes advantage of user assertions, and it enhances program verification because assertions can be refined using automatic program analysis. Both enhancements in general produce a ... | Introduction
abstraction [9] is a successful method of abstract
interpretation. The abstract domain, constructed from
a given finite set of predicates over program variables, is
intuitive and easily, though not necessarily efficiently, computable
within a traversal method of the program's control
flow structure. More r... | program analysis;program verification;abstract interpretation |
325874 | Optimizing Queries with Object Updates. | Object-oriented databases (OODBs) provide powerful data abstractions and modeling facilities but they usually lack a suitable framework for query processing and optimization. Even though there is an increasing number of recent proposals on OODB query optimization, only few of them are actually focused on query optimiza... | Introduction
One of the key factors for OODB systems to successfully compete with relational systems as well as to
meet the performance requirements of many non-traditional applications is the development of an effective
query optimizer. Even though there are many aspects to the OODB query optimization problem that can... | query optimization;monoid comprehensions;denotational semantics;object identity |
325884 | Using Model Trees for Classification. | Model trees, which are a type of decision tree with linear regression functions at the leaves, form the basis of a recent successful technique for predicting continuous numeric values. They can be applied to classification problems by employing a standard method of transforming a classification problem into a problem o... | Introduction
Many applications of machine learning in practice involve predicting a "class" that
takes on a continuous numeric value, and the technique of model tree induction has
proved successful in addressing such problems (Quinlan, 1992; Wang and Witten,
1997). Structurally, a model tree takes the form of a decisio... | <math coding=latex type=inline>M5;<math coding=latex type=inline>C50;classification algorithms;decision trees;model trees |
325958 | Hybrid Gauss-Trapezoidal Quadrature Rules. | A new class of quadrature rules for the integration of both regular and singular functions is constructed and analyzed. For each rule the quadrature weights are positive and the class includes rules of arbitrarily high-order convergence. The quadratures result from alterations to the trapezoidal rule, in which a small ... | r
2.2. Euler{Maclaurin summation formula. For a function f 2 Cp(R), p
1, the Euler{Maclaurin summation formula (see, for example, [15, (23.1.30)]) can be
derived by repeated integration by parts. We rst consider the interval
apply (5) to obtain
Z c+h Z 1
where we have derive the Euler{Maclaurin formula for the interval... | high-order convergence;numerical integration;positive weights;singularity;gaussian quadrature;euler-maclaurin formula |
325962 | Simulations of Acoustic Wave Phenomena Using High-Order Finite Difference Approximations. | Numerical studies of hyperbolic initial boundary value problems (IBVP) in several space dimensions have been performed using high-order finite difference approximations. It is shown that for wave propagation problems, where the wavelengths are small compared to the domain and long time integrations are needed, high-ord... | Introduction
In this paper we present results of numerical simulations using high-order finite difference
methods. In particular we are interested in hyperbolic wave propagation
problems where accurate long time integrations are needed. For such problems
high accuracy in both time and space are needed if an accurate so... | hyperbolic initial boundary value problems;wave propagation;high-order finite difference;acoustics |
325976 | Orderings for Incomplete Factorization Preconditioning of Nonsymmetric Problems. | Numerical experiments are presented whereby the effect of reorderings on the convergence of preconditioned Krylov subspace methods for the solution of nonsymmetric linear systems is shown. The preconditioners used in this study are different variants of incomplete factorizations. It is shown that certain reorderings fo... | Introduction
. In this paper, we study experimentally how di#erent reorderings
a#ect the convergence of Krylov subspace methods for nonsymmetric systems of
linear equations when incomplete LU factorizations are used as preconditioners. In
other words, given a sparse linear system of equations are n-dimensional
vectors,... | nonsymmetric matrices;incomplete factorizations;preconditioned iterative methods;linear systems;krylov subspace methods;permutation of sparse matrices;reorderings |
326447 | The impact on retrieval effectiveness of skewed frequency distributions. | We present an analysis of word senses that provides a fresh insight into the impact of word ambiguity on retrieval effectiveness with potential broader implications for other processes of information retrieval. Using a methodology of forming artifically ambiguous words, known as pseudowords, and through reference to ot... | Introduction
A great many words in natural languages are ambiguous. The resolution
of ambiguity is a task that has concerned a great many
researchers in the field of Computational Linguistics. Over the
years, many programs have been built that, given a word appearing
in a certain context (with a definition of the word'... | word sense disambiguation;pseudowords;word sense ambiguity |
327790 | A Parallel Algorithm for Mesh Smoothing. | Maintaining good mesh quality during the generation and refinement of unstructured meshes in finite-element applications is an important aspect in obtaining accurate discretizations and well-conditioned linear systems. In this article, we present a mesh-smoothing algorithm based on nonsmooth optimization techniques and... | Introduction
. Unstructured meshes have proven to be an essential tool in the numerical
solution of large-scale scientific and engineering applications on complex computational domains. A
problem with such meshes is that the shape of the elements in the mesh can vary significantly, and
this variation can affect the acc... | finite elements;parallel algorithms;mesh smoothing;parallel computing;unstructured meshes |
327833 | An Efficient Algorithm for a Bounded Errors-in-Variables Model. | We pose and solve a parameter estimation problem in the presence of bounded data uncertainties. The problem involves a minimization step and admits a closed form solution in terms of the positive root of a secular equation. | Introduction
. Parameter estimation in the presence of data uncertainties
is a problem of considerable practical importance, and many estimators have been
proposed in the literature with the intent of handling modeling errors and measurement
noise. Among the most notable is the total least-squares method [1, 2, 3, 4],
... | modeling errors;least-squares estimation;total least-squares;secular equation |
327849 | The Design and Use of Algorithms for Permuting Large Entries to the Diagonal of Sparse Matrices. | We consider techniques for permuting a sparse matrix so that the diagonal of the permuted matrix has entries of large absolute value. We discuss various criteria for this and consider their implementation as computer codes. We then indicate several cases where such a permutation can be useful. These include the solut... | Introduction
We study algorithms for the permutation of a square unsymmetric sparse matrix A
of order n so that the diagonal of the permuted matrix has large entries. This can
be useful in several ways. If we wish to solve the system
where A is a nonsingular square matrix of order n and x and b are vectors of length
n,... | sparse matrices;iterative methods;maximum transversal;preconditioning;direct methods |
328033 | New Parallel SOR Method by Domain Partitioning. | In this paper we propose and analyze a new parallel SOR method, the PSOR method, formulated by using domain partitioning and interprocessor data communication techniques. We prove that the PSOR method has the same asymptotic rate of convergence as the Red/Black (R/B) SOR method for the five-point stencil on both strip ... | Introduction
. The successive over-relaxation (SOR) iterative method is an
important solver for large linear systems [22]. It is also a robust smoother as well as an
efficient solver of the coarsest grid equations in the multigrid method [20]. However, the
SOR method is essentially sequential in its original form. With... | SOR;JSOR;nonmigratory permutation;convergence analysis;PSOR;multicolor SOR;parallel computing |
328127 | Performance of Greedy Ordering Heuristics for Sparse Cholesky Factorization. | Greedy algorithms for ordering sparse matrices for Cholesky factorization can be based on different metrics. Minimum degree, a popular and effective greedy ordering scheme, minimizes the number of nonzero entries in the rank-1 update (degree) at each step of the factorization. Alternatively, minimum deficiency minimize... | Introduction
. It is well known that ordering the rows and columns of a matrix
is a crucial step in the solution of sparse linear systems using Gaussian elimination. The
ordering can drastically affect the amount of fill introduced during factorization and hence
the cost of computing the factorization [7, 13]. When the... | minimum degree;sparse matrix ordering;greedy heuristics;minimum deficiency |
328138 | Block Stationary Methods for Nonsymmetric Cyclically Reduced Systems Arising from Three-Dimensional Elliptic Equations. | We consider a three-dimensional convection-diffusion model problem and examine systems of equations arising from performing one step of cyclic reduction on an equally spaced mesh, discretized using the seven-point operator. We present two ordering strategies and analyze block splittings of the resulting matrices. If th... | Introduction
. Consider the three-dimensional (3D) convection-di#usion equation
with constant coe#cients
y, z)
on the unit
subject to Dirichlet-type boundary con-
ditions. We focus on applying seven-point finite di#erence discretizations, for example
centered di#erences to the di#usive terms, and centered di#erences or... | convection-diffusion;cyclic reduction;stationary methods;three-dimensional problems |
329333 | Efficient support for interactive scanning operations in MPEG-based video-on-demand systems. | In this paper, we present an efficient approachfor supporting fast-scanning (FS) operations in MPEG-based video-on-demand (VOD) systems. This approach is based onstoring multiple, differently encoded versions of the samemovie at the server. A <i>normal version</i> is used for normalplayback, while several <i>scan versi... | Introduction
The maturing of video compression technologies, magnetic storage subsystems, and broadband networking
has made video-on-demand (VOD) over computer networks more viable than ever. Major
carriers have tested small-scale VOD systems, and companies that provide related services and products
are emerging (cf. [... | video scheduling;MPEG;scanning operations;interactive video-on-demand |
329345 | Providing QoS guarantees for disk I/O. | In this paper, we address the problem of providing different levels of performance guarantees or quality ofservice for disk I/O. We classify disk requests into threecategories based on the provided level of service. We propose an integrated scheme that provides different levels ofperformance guarantees in a single syst... | Introduction
System level support of continuous media has been receiving wide attention. Continuous media
impose timing requirements on the retrieval and delivery of data unlike traditional data such as
text and images. Timely retrieval and delivery of data requires that the system and network pay
attention to notions ... | seek optimization;disk scheduling;multiple QoS goals;VBR streams |
329351 | Automatic text segmentation and text recognition for video indexing. | Efficient indexing and retrieval of digital videois an important function of video databases. One powerfulindex for retrieval is the text appearing in them. It enablescontent-based browsing. We present our new methods forautomatic segmentation of text in digital videos. The algorithms we propose make use of typical cha... | INTRODUCTION
There is no doubt that video is an increasingly important
modern information medium. Setting free its complete
potential and usefulness requires efficient content-based
indexing and access. One powerful high-level index for
retrieval is the text contained in videos. This index can be
built by detecting, ex... | OCR;text recognition;video indexing;video content analysis;video processing;character segmentation |
329461 | A code-motion pruning technique for global scheduling. | In the high-level synthesis of ASICs or in the code generation for ASIPs, the presence of conditionals in the behavioral description represents an obstacle to exploit parallelism. Most existing methods use greedy choices in such a way that the search space is limited by the applied heuristics. For example, they might m... | INTRODUCTION
In the high-level synthesis of an application-specific integrated circuit (ASIC) or in the code generation
for an application-specific instruction set processor (ASIP), four main difficulties have to be faced during
scheduling when conditionals and loops are present in the behavioral description:
a) the NP... | speculative execution;code generation;global scheduling;code motion;high-level synthesis |
329831 | Decision Analysis by Augmented Probability Simulation. | We provide a generic Monte Carlo method to find the alternative of maximum expected utility in a decision analysis. We define an artificial distribution on the product space of alternatives and states, and show that the optimal alternative is the mode of the implied marginal distribution on the alternatives. After draw... | Introduction
1.1 Decision Analysis by Simulation
Decision Analysis provides a framework for solving decision making problems under uncer-
tainty, based on finding an alternative with maximum expected utility. While conceptually
simple, the actual solution of the maximization problem may be extremely involved, e.g.,
whe... | simulation;decision analysis;influence diagrams;optimal design;Markov Chain Monte Carlo |
330333 | Probabilistic Loop Scheduling for Applications with Uncertain Execution Time. | AbstractOne of the difficulties in high-level synthesis and compiler optimization is obtaining a good schedule without knowing the exact computation time of the tasks involved. The uncertain computation times of these tasks normally occur when conditional instructions are employed and/or inputs of the tasks influence t... | Introduction
In many practical applications such as interface systems, fuzzy systems, articial intelligence systems, and
others, the required tasks normally have uncertain computation times (called uncertain or probabilistic
tasks for brevity). Such tasks normally contain conditional instructions and/or operations that... | retiming;probabilistic approach;loop pipelining;scheduling;rotation scheduling |
330348 | Modules via Concept Analysis. | AbstractWe describe a general technique for identifying modules in legacy code. The method is based on concept analysisa branch of lattice theory that can be used to identify similarities among a set of objects based on their attributes. We discuss how concept analysis can identify potential modules using both positive... | Introduction
Many existing software systems were developed using programming languages and paradigms that
do not incorporate object-oriented features and design principles. These systems often have a
monolithic style that makes maintenance and further enhancement an arduous task. The software
engineer's job would be le... | concept analysis;software restructuring;design recovery;reverse engineering;software migration;modularization |
330351 | Managing Process Inconsistency Using Viewpoints. | AbstractThis paper discusses the notion of process inconsistency and suggests that inconsistencies in software processes are inevitable and sometimes desirable. We present an approach to process analysis that helps discover different perceptions of a software process and that supports the discovery of process inconsist... | Introduction
Over the past few years, there has been a growing awareness that organisations can leverage
significant productivity improvements by improving their business processes. Software
development processes are one class of business process which have received particular
attention and, since the early 1980s, a si... | viewpoints;software process;process improvement |
330354 | Managing Requirements Inconsistency with Development Goal Monitors. | AbstractManaging the development of software requirements can be a complex and difficult task. The environment is often chaotic. As analysts and customers leave the project, they are replaced by others who drive development in new directions. As a result, inconsistencies arise. Newer requirements introduce inconsistenc... | INTRODUCTION
Requirements engineering can be characterized as an iterative process of discovery and analysis
designed to produce an agreed-upon set of clear, complete, and consistent system requirements.
The process is complex and difficult to manage, involving the surfacing of stakeholder views,
developing shared unde... | inconsistency and conflict management;meta-modeling;process modeling and monitoring;requirements engineering;CASE |
330365 | Finding Separator Cuts in Planar Graphs within Twice the Optimal. | A factor 2 approximation algorithm for the problem of finding a minimum-cost b-balanced cut in planar graphs is presented, for $b \leq {1 \over 3}$. We assume that the vertex weights are given in unary; for the case of binary vertex weights, a pseudoapproximation algorithm is presented. This problem is of considerable ... | Introduction
Given an undirected graph with edge costs and vertex weights, the balance of a cut is the ratio
of the weight of vertices on the smaller side to the total weight in the graph. For
cut having a balance of at least b is called a b-balanced cut; a 1
-balanced cut is given the special
name of a separator. In t... | approximation algorithms;planar graphs;separators |
330368 | Achilles, Turtle, and Undecidable Boundedness Problems for Small DATALOG Programs. | DATALOG is the language of logic programs without function symbols. It is considered to be the paradigmatic database query language. If it is possible to eliminate recursion from a DATALOG program then it is bounded. Since bounded programs can be executed in parallel constant time, the possibility of automatized bo... | Introduction
.
1.1.
Introduction
. The query relation R, that answers, for a given directed
graph (database), if that is possible, for given two nodes, to reach one of them from
the other in an odd number of steps, is not a first order one. That is because of lack
of recursion in the first order logic. This observati... | query optimization;decidability;DATALOG |
330373 | Equivalence of Measures of Complexity Classes. | The resource-bounded measures of complexity classes are shown to be robust with respect to certain changes in the underlying probability measure. Specifically, for any real number $\delta > 0$, any uniformly polynomial-time computable sequence \ldots )$ of real numbers (biases) $\beta_i \in [\delta, 1-\delta]$, and for... | Introduction
In the 1990's, the measure-theoretic study of complexity classes has yielded
a growing body of new, quantitative insights into various much-studied aspects
of computational complexity. Benefits of this study to date include
improved bounds on the densities of hard languages [15]; newly discovered
relations... | complexity classes;martingales;resource-bounded measure |
330384 | Unlinkable serial transactions. | We present a protocol for unlinkable serial transactions suitable for a variety of network-based subscription services. It is the first protocol to use cryptographic blinding to enable subscription services. The protocol prevents the service from tracking the behavior of its customers, while protecting the service vend... | Introduction
This paper is motivated by an apparent conflict of interest concerning the privacy
of information in an electronic exchange. Commercial service providers would
like to be sure that they are paid for their services and protected from abuse
due to simultaneous or "cloned" usage from a single subscription. To... | cryptographic protocols;anoymity;blinding;unlinkable serial transactions |
330386 | On secure and pseudonymous client-relationships with multiple servers. | This paper introduces a cryptographic engine, Janus, which assists clients in establishing and maintaining secure and pseudonymous relationships with multiple servers. The setting is such that clients reside on a particular subnet (e.g., corporate intranet, ISP) and the servers reside anywhere on the Internet. The Janu... | Introduction
We consider the following problem: there is a set
of clients located on a particular subnet and a set
of servers on the Internet. For example, the set
of clients could be employees on a company's intranet
or subscribers of an ISP and the servers could
be Web-sites. See Figure 1, where c i are clients
and s... | privacy;pseudonym;persistent relationship;janus function;mailbox;anonymity |
330390 | Strength of two data encryption standard implementations under timing attacks. | We study the vulnerability of two implementations of the Data Encryption Standard (DES) cryptosystem under a timing attack. A timing attack is a method, recently proposed by Paul Kocher, that is designed to break cryptographic systems. It exploits the engineering aspects involved in the implementation of cryptosystems ... | INTRODUCTION
An ingenious new type of cryptanalytic attack was introduced by Kocher in [Kocher
1996]. This new attack is called timing attack. It exploits the fact that cryptosystems
often take slightly different amounts of time on different inputs. Kocher gave
several possible explanations for this behavior, among the... | cryptography;data encryption standard;timing attack;cryptanalysis |
330445 | Distributed Path Reservation Algorithms for Multiplexed All-Optical Interconnection Networks. | AbstractIn this paper, we study distributed path reservation protocols for multiplexed all-optical interconnection networks. The path reservation protocols negotiate the reservation and establishment of connections that arrive dynamically to the network. These protocols can be applied to both wavelength division multip... | Introduction
With the increasing computation power of parallel
computers, interprocessor communication has become
an important factor that limits the performance of supercomputing
systems. Due to their capabilities of
offering large bandwidth, optical interconnection net-
works, whose advantages have been well demonstr... | routing protocols;distributed control;mesh-like networks;optical interconnection networks;path reservation;wavelength-division multiplexing;time-division multiplexing |
330512 | How Useful Is Old Information?. | AbstractWe consider the problem of load balancing in dynamic distributed systems in cases where new incoming tasks can make use of old information. For example, consider a multiprocessor system where incoming tasks with exponentially distributed service requirements arrive as a Poisson process, the tasks must choose a ... | Introduction
Distributed computing systems, such as networks of workstations or mirrored sites
on the World Wide Web, face the problem of using their resources effectively. If some
hosts lie idle while others are heavily loaded, system performance can fall significantly.
To prevent this, load balancing is used to distr... | large deviations;old information;load balancing;queuing theory;stale information |
331217 | Efficient Algorithms for Block-Cyclic Array Redistribution Between Processor Sets. | AbstractRun-time array redistribution is necessary to enhance the performance of parallel programs on distributed memory supercomputers. In this paper, we present an efficient algorithm for array redistribution from cyclic(x) on $P$ processors to cyclic(Kx) on $Q$ processors. The algorithm reduces the overall time for ... | Introduction
Many High Performance Computing (HPC) applications, including scientific computing and signal
processing, consist of several stages [2, 10, 22]. Examples of such applications include the multi-dimensional
Fast Fourier Transform, the Alternative Direction Implicit (ADI) method for solving
two-dimensional di... | block-cyclic distribution;interprocessor communication;redistribution algorithms |
331220 | Tight Bounds for Prefetching and Buffer Management Algorithms for Parallel I/O Systems. | AbstractThe I/O performance of applications in multiple-disk systems can be improved by overlapping disk accesses. This requires the use of appropriate prefetching and buffer management algorithms that ensure the most useful blocks are accessed and retained in the buffer. In this paper, we answer several fundamental qu... | Introduction
The increasing imbalance between the speeds of processors and I/O devices has
resulted in the I/O subsystem becoming a bottleneck in many applications. The
use of multiple disks to build a parallel I/O subsystem has been advocated to increase
I/O performance and system availability [5], and most high-perfo... | external memory;competitive ratio;prefetching;algorithms;multiple-disk systems;buffer management;caching;Parallel I/O |
331224 | Universal Constructions for Large Objects. | AbstractWe present lock-free and wait-free universal constructions for implementing large shared objects. Most previous universal constructions require processes to copy the entire object state, which is impractical for large objects. Previous attempts to address this problem require programmers to explicitly fragment ... | Introduction
This paper extends recent research on universal lock-free and wait-free constructions of
shared objects [3, 4]. Such constructions can be used to implement any object in a lock-free
or a wait-free manner, and thus can be used as the basis for a general methodology
for constructing highly-concurrent objects... | shared objects;concurrency;wait-free;lock-free;nonblocking synchronization |
331273 | Stereo Matching with Transparency and Matting. | This paper formulates and solves a new variant of the stereo correspondence problem: simultaneously recovering the disparities, true colors, and opacities of visible surface elements. This problem arises in newer applications of stereo reconstruction, such as view interpolation and the layering of real imagery with syn... | Introduction
Stereo matching has long been one of the central research problems in computer vision. Early
work was motivated by the desire to recover depth maps and shape models for robotics and
object recognition applications. More recently, depth maps obtained from stereo have been
painted with texture maps extracted... | transparency;matting problem;stereo correspondence;3D representations;occlusions;3D reconstruction |
331525 | Automatically Checking an Implementation against Its Formal Specification. | AbstractWe propose checking the execution of an abstract data type's imperative implementation against its algebraic specification. An explicit mapping from implementation states to abstract values is added to the imperative code. The form of specification allows mechanical checking of desirable properties such as cons... | Introduction
Encapsulated data abstractions, also called abstract data types (ADTs), are the most promising
programming-language idea to support software engineering. The ADT is the basis for the "informa-
tion-hiding" design philosophy [50] that makes software easier to analyze and understand, and that
can hope to sup... | rewriting;formal specification;self-checking code;object-oriented software testing |
331607 | Parallel RAMs with owned global memory and deterministic context-free language recognition. | We identify and study a natural and frequently occurring subclass of Concurrent Read, Exclusive Write Parallel Random Access Machines (CREW-PRAMs). Called Concurrent Read, Owner Write, or CROW-PRAMS, these are machines in which each global memory location is assigned a unique owner processor, which is the only processo... | under several definitional changes. Second, we precisely characterize
the power of the CROW-PRAM by showing that the class of languages
recognizable by it in time O(log n) is exactly the class LOGDCFL of
languages log space reducible to deterministic context free languages.
Third, using the same basic machinery, we sho... | CROW-PRAM;owner write;parallel algorithms;DCFL recognition |
331778 | Human-guided simple search. | Scheduling, routing, and layout tasks are examples of hard operations-research problems that have broad application in industry. Typical algorithms for these problems combine some form of gradient descent to find local minima with some strategy for escaping nonoptimal local minima and traversing the search space. Our i... | Introduction
Most previous research on scheduling, routing, and lay-out
problems has focused on developing fully automatic
solution methods. There are, however, at least two reasons
for developing cooperative, interactive systems for
optimization problems like these. First, human users
may have knowledge of various amo... | combinatorial optimization;operations research;interactions systems;vehicle routing;computer-human interaction;informtaion visualization |
332405 | Two-handed input using a PDA and a mouse. | We performed several experiments using a Personal Digital Assistant (PDA) as an input device in the non-dominant hand along with a mouse in the dominant hand. A PDA is a small hand-held palm-size computer like a 3Com Palm Pilot or a Windows CE device. These are becoming widely available and are easily connected to a PC... | INTRODUCTION
Many studies of two-handed input for computers have often
shown advantages for various tasks [1, 3, 7, 9, 15].
However, people rarely have the option of using more than
just a mouse and keyboard because other input devices are
relatively expensive, awkward to set up, and few applications
can take advantage... | ubiquitous computing;two-handed input;hand-held computers;Windows CE;personal digital assistant PDAs;palm pilot;pebbles;smart environments |
332540 | Reconstructing distances in physical maps of chromosomes with nonoverlapping probes. | We present a new method for reconstructing the distances between probes in physical maps of chromosomes constructed by hybridizing pairs of clones under the so-called sampling-without-replacement protocol. In this protocol, which is simple, inexpensive, and has been used to successfully map several organisms, equal-len... | Introduction
Physical mapping in molecular biology is the task of reconstructing
the order and location of features of biological
interest along a chromosome. The features may be
Corresponding author. Department of Computer Science, University
of Georgia, Athens, GA 30602-7404. Email: kece@cs.uga.edu.
Research supporte... | maximum likelihood;physical mapping of chromosomes;sampling without replacement protocol;convex optimization;computational biology |
332877 | Design and Implementation of Efficient Message Scheduling for Controller Area Network. | AbstractThe Controller Area Network (CAN) is being widely used in real-time control applications such as automobiles, aircraft, and automated factories. In this paper, we present the mixed traffic scheduler (MTS) for CAN, which provides higher schedulability than fixed-priority schemes like deadline-monotonic (DM) whil... | Introduction
Distributed real-time systems are being used increasingly in control applications such as in automobiles,
aircraft, robotics, and process control. These systems consist of multiple computational nodes, sensors, and
actuators interconnected by a LAN [3]. Of the multiple LAN protocols available for such use ... | priority inversion;Controller Area Network CAN;message scheduling;distributed real-time systems;network scheduling implementation |
332948 | Analysis of ISP IP/ATM network traffic measurements. | This paper presents network traffic measurements collected from a commercial Internet Service Provider (ISP) whose traffic is being carried over an ATM backbone network. Much of the aggregate traffic is Web-related, and thus represents a Web/TCP/IP/AAL-5/ATM protocol stack. Four traces have been collected at the AAL-5 ... | Introduction
This paper presents network traffic measurements
from a commercial Internet Service Provider
(ISP) environment in western Canada. This ISP
offers Internet service (primarily Web access) to
its customers, and is using an OC-3 (155 Mbps)
ATM backbone network to carry the traffic. The
TCP/IP packet traffic is... | network traffic measurement;ATM networks;TCP/IP;wworkload characterization |
333131 | Improved Approximation Guarantees for Packing and Covering Integer Programs. | Several important NP-hard combinatorial optimization problems can be posed as packing/covering integer programs; the randomized rounding technique of Raghavan and Thompson is a powerful tool with which to approximate them well. We present one elementary unifying property of all these integer linear programs and use t... | Introduction
Several important NP-hard combinatorial optimization problems such as basic
problems on graphs and hypergraphs, can be posed as packing/covering integer
programs; the randomized rounding technique of Raghavan & Thompson is a
powerful tool to approximate them well [21]. We present an elementary property
of ... | integer programming;linear programming;positive correlation;combinatorial optimization;correlation inequalities;approximation algorithms;packing integer programs;derandomization;rounding theorems;covering integer programs;linear relaxations;randomized rounding |
333225 | Image Sequence Analysis via Partial Differential Equations. | This article deals with the problem of restoring and motion segmenting noisy image sequences with a static background. Usually, motion segmentation and image restoration are considered separately in image sequence restoration. Moreover, motion segmentation is often noise sensitive. In this article, the motion segmentat... | Introduction
Automatic image sequence restoration is clearly a
very important problem. Applications areas include
image surveillance, forensic image process-
ing, image compression, digital video broadcast-
ing, digital -lm restoration, medical image pro-
cessing, remote sensing example, the
recent work done within the... | discontinuity preserving regularization;space of functions of bounded variation;variational approaches;sequence image restoration;motion segmentation |
333323 | The Conditioning of Boundary Element Equations on Locally Refined Meshes and Preconditioning by Diagonal Scaling. | Consider a boundary integral operator on a bounded,d-dimensional surface in $\mbox{\smallBbb R}^{d+1}$. Suppose that the operator is a pseudodifferential operator of order $2m,$ $m\in\mbox{\smallBbb R},$ and that the associated bilinear form is symmetric and positive-definite. (The surface may be open or closed, and m ... | Introduction
\Gamma be a bounded, d-dimensional, open or closed surface in R d+1 , where d - 1.
H s (\Gamma) denote the usual Sobolev spaces. Precise definitions and
assumptions are deferred until a later section. However, observe if \Gamma is a closed
surface then the spaces e
H s (\Gamma) and H s (\Gamma) coincide si... | diagonal scaling;condition numbers;boundary element method;preconditioning |
333369 | Modeling a Hardware Synthesis Methodology in Isabelle. | Formal Synthesis is a methodology developed at the university of Kent for combining circuit design and verification, where a circuit is constructed from a proof that it meets a given formal specification. We have reinterpreted this methodology in ISABELLES theory of higher-order logic so that circuits are incrementally... | Introduction
Verification by formal proof is time intensive and this is a burden in bringing
formal methods into software and hardware design. One approach to reducing the
verification burden is to combine development and verification by using a calculus
where development steps either guarantee correctness or, since pr... | higher-order logic;hardware verification and synthesis;higher-order unification;theorem proving |
333469 | A Subspace, Interior, and Conjugate Gradient Method for Large-Scale Bound-Constrained Minimization Problems. | A subspace adaptation of the Coleman--Li trust region and interior method is proposed for solving large-scale bound-constrained minimization problems. This method can be implemented with either sparse Cholesky factorization or conjugate gradient computation. Under reasonable conditions the convergence properties of thi... | Introduction
. Recently Coleman and Li [1, 2, 3] proposed two interior and reflective Newton
methods to solve the bound-constrained minimization problem, i.e.,
min
algorithms are interior methods since the iterates fx k g are in the strict interior of the feasible region, i.e.,
ug. These two methods differ in that a li... | interior method;trust region method;box constraints;bound-constrained problem;inexact Newton step;conjugate gradients;negative curvature direction |
333474 | Pivoted Cauchy-Like Preconditioners for Regularized Solution of Ill-Posed Problems. | Many ill-posed problems are solved using a discretization that results in a least squares problem or a linear system involving a Toeplitz matrix. The exact solution to such problems is often hopelessly contaminated by noise, since the discretized problem is quite ill conditioned, and noise components in the approximate... | Introduction
. In fields such as seismography, tomography, and signal pro-
cessing, the process describing the acquisition of data can often be described by an
integral equation of the first kind
Z fi up
lo
where t denotes the kernel, -
f the unknown input function, and - g the output. When
it is appropriately discreti... | cauchy-like;toeplitz;conjugate gradient;least squares;preconditioner;regularization;ill-posed problems |
333696 | Learning and Design of Principal Curves. | AbstractPrincipal curves have been defined as self-consistent smooth curves which pass through the middle of a d-dimensional probability distribution or data cloud. They give a summary of the data and also serve as an efficient feature extraction tool. We take a new approach by defining principal curves as continuous c... | Introduction
Principal component analysis is perhaps the best-known technique in multivariate analysis
and is used in dimension reduction, feature extraction, and in image coding and enhancement.
Consider a d-dimensional random vector moments.
The first principal component line for X is a straight line which has the pr... | curve fitting;feature extraction;learning systems;unsupervised learning;piecewise linear approximation;vector quantization |
333779 | Derivation of Numerical Methods Using Computer Algebra. | The use of computer algebra systems in a course on scientific computation is demonstrated. Various examples, such as the derivation of Newton's iteration formula, the secant method, Newton--Cotes and Gaussian integration formulas, as well as Runge--Kutta formulas, are presented. For the derivations, the computer algebr... | Introduction
At ETH Z-urich we have redesigned our former courses on numerical analysis. We do not only run
numerical programs but also introduce the students to computer algebra and make heavy use of
computer algebra systems both in the lectures and the assignments.
Computer algebra may be used to generate numerical a... | finite elements;numerical methods;computer algebra;maple;rayleigh-ritz;galerkin method;runge-kutta method;nonlinear equations;quadrature formulas |
333849 | Edge-Bandwidth of Graphs. | The edge-bandwidth of a graph is the minimum, over all labelings of the edges with distinct integers, of the maximum difference between labels of two incident edges. We prove that edge-bandwidth is at least as large as bandwidth for every graph, with equality for certain caterpillars. We obtain sharp or nearly sharp b... | INTRODUCTION
A classical optimization problem is to label the vertices of a graph with distinct integers
so that the maximum difference between labels on adjacent vertices is minimized. For
a graph G, the optimal bound on the differences is the bandwidth B(G). The name arises
from computations with sparse symmetric mat... | bandwidth;edge-bandwidth;biclique;caterpillar;clique |
333895 | Backward Error Analysis for Numerical Integrators. | Backward error analysis has become an important tool for understanding the long time behavior of numerical integration methods. This is true in particular for the integration of Hamiltonian systems where backward error analysis can be used to show that a symplectic method will conserve energy over exponentially long pe... | Introduction
. In this paper, we consider the relationship between solutions
to a given system of ordinary differential equations (vector fields)
d
dt
numerical approximations
to them, and solutions to associated modified equations
d
dt
The vector fields ~
are formulated in terms of an asymptotic expansion in the
step-... | hamiltonian systems;error analysis;long time dynamics;differential equations;numerical integrators |
333931 | Reduced Systems for Three-Dimensional Elliptic Equations with Variable Coefficients. | We consider large sparse nonsymmetric linear systems arising from finite difference discretization of three-dimensional (3D) convection-diffusion equations with variable coefficients. We show that performing one step of cyclic reduction yields a system of equations which is well conditioned and for which fast conver... | Introduction
. Consider the following three-dimensional (3D) convection-
di#usion equation
on a
domain# R 3 , subject to Dirichlet, Neumann, or mixed boundary condi-
tions, where all the functions in (1.1) are trivariate, and p, q, r > 0 on # Several
discretization schemes are possible. See Morton [11] for a comprehens... | cyclic reduction;variable coefficients;3D elliptic problems |
334051 | On the Sequence of Consecutive Powers of a Matrix in a Boolean Algebra. | In this paper we consider the sequence of consecutive powers of a matrix in a Boolean algebra. We characterize the ultimate behavior of this sequence, we study the transient part of the sequence, and we derive upper bounds for the length of this transient part. We also indicate how these results can be used in the anal... | Introduction
. In this paper we consider the sequence of consecutive powers
of a matrix in a Boolean algebra. This sequence reaches a \cyclic" behavior
after a nite number of terms. Even for more complex algebraic structures, such as
the max-plus algebra (which has maximization and addition as its basic operations)
thi... | transient behavior;max-plus algebra;boolean matrices;boolean algebra;markov chains |
334141 | The Compactness of Interval Routing. | The compactness of a graph measures the space complexity of its shortest path routing tables. Each outgoing edge of a node x is assigned a (pairwise disjoint) set of addresses, such that the unique outgoing edge containing the address of a node y is the first edge of a shortest path from x to y. The complexity measure ... | Introduction
An interval routing scheme is a way of implenting routing schemes on arbitrary
networks. It is based on representing the routing table stored at each node in a
compact manner, by grouping the set of destination addresses that use the same
output port into intervals of consecutive addresses. A possible way ... | shortest path;random graphs;compact routing tables;interval routing |
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