Browsing Technical Reports from UMIACS by Issue Date
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Scheduling Aperiodic and Sporadic Tasks in Hard RealTime Systems
(19981015)The stringent timing constraints as well as the functional correctness are essential requirements of hard realtime systems. In such systems, scheduling plays a very important role in satisfying these constraints. The ... 
The NewYacc User's Manual
(19981015)This manual introduces NewYacc, a parser generator system built upon the original yacc system within Unix. NewYacc's principal extension is to provide users with a way to associate rewrite rules with individual productions ... 
An ErrorTheory of Consciousness
(19981015)I argue that consciousness is an aspect of an agent's intelligence, hence of its ability to deal adaptively with the world. In particular, it allows for the possibility of noting and correcting the agent's own errors. This ... 
DomainDriven Reconfiguration in Collaborative Virtual Environments
(19981015)When virtual environments (VE) collaborate to create a shared virtual world, events occur that can have catastrophic effects on that virtual world. These events can be system events, such as the loss of a host or a network ... 
Numerical Methods for M/G/1 Type Queues
(19981015)Queues of M/G/1 type give rise to infinite embedded Markov chains whose transition matrices are upper block Hessenberg. The traditional algorithms for solving these queues have involved the computation of an intermediate ... 
SpaceEfficient Hot Spot Estimation
(19981015)This paper is concerned with the problem of identifying names which occur frequently in an ordered list of names. Such names are called hot spots. Hot spots can be identified easily by counting the occurrences of ... 
Project for Developing Computer Science Agenda(s) for HighPerformance Computing: An Organizer's Summary
(19981015)Designing a coherent agenda for the implementation of the High Performance Computing (HPC) program is a nontrivial technical challenge. Many computer science and engineering researchers in the area of HPC, who are ... 
A Packager for Multicast Software in Distributed Systems
(19981015)PTM is a packagmg tool for preparing ordinary software to execute in multicastbased environments. Using PTM, both individual programs and systems of programs can be tailored to use multicast communication, without manual ... 
Simplifying Polynomial Constraints Over Integers to Make Dependence Analysis More Precise
(19981015)Why do existing parallelizing compilers and environments fail to parallelize many realistic FORTRAN programs? One of the reasons is that these programs contain a number of linearized array references, such as ... 
Gaussian Elimination, Perturbation Theory and Markov Chains
(19981015)The purpose of this paper is to describe the special problems that emerge when Gaussian elimination is used to determinin the steadystate vector of a Markov chain. (Also crossreferenced as UMIACSTR9223) 
On the Sensitivity of Nearly Uncoupled Markov Chains
(19981015)Nearly uncoupled Markov chains (aka nearly completely decomposable Markov chains) arise in a variety of applications, where they model loosely coupled systems. In such systems it may be difficult to determine the transitions ... 
Efficient Incremental Garbage Collection for Workstation/Server Database Systems
(19981015)We describe an efficient serverbased algorithm for garbage collecting objectoriented databases in a workstation/server environment. The algorithm is incremental and runs concurrently with client transactions, however, ... 
Fast TimeDependent Evaluation of Integrated Services Networks
(19981015)We present a numericalanalytical method to evaluate integrated services networks with adaptive routing, scheduling and admission controls. We apply our method to connectionoriented networks supporting different types ... 
Data Parallel Programming in an Adaptive Environment
(19981015)For better utilization of computing resources, it is important to consider parallel programming environments in which the number of available processors varies at runtime. In this paper, we discuss runtime support ... 
On Graded QR Decompositions of Products of Matrices
(19981015)This paper is concerned with the singular values and vectors of a product $M_{m}=A_{1}A_{2}\cdots A_{m}$ of matrices of order $n$. The chief difficulty with computing them from directly from $M_{m}$ is that with increasing ... 
A Unified Treatment of Null Values using Constraints
(19981015)An important reality when studying relational databases is the fact that entries in relational tables may often be "missing" or only partially specified. The study of such missing information has led to a rich body of ... 
Slicing RealTime Programs for Enhanced Schedulability
(19981015)(Also crossreferenced as UMIACSTR9562) 
Counting Solutions to Presburger Formulas: How and Why
(19981015)We describe methods that are able to count the number of integer solutions to selected free variables of a Presburger formula, or sum a polynomial over all integer solutions of selected free variables of a Presburger ... 
Eliminating False Data Dependences using the Omega Test
(19981015)Array data dependence analysis methods currently in use generate false dependences that can prevent useful program transformations. These false dependences arise because the questions asked are conservative ... 
Beyond Uniformity and Independence: Analysis of RTrees Using the Concept of Fractal Dimension",
(19981015)We propose the concept of fractal dimension of a set of points, in order to quantify the deviation from the uniformity distribution. Using measurements on real data sets (road intersections of U.S. counties, star coordinates ...