ppxscal/embedding_network huggingface dataset:
Convex-Round and Concave-Round Graphs
Authors: Jørgen Bang-Jensen, Jing Huang, Anders Yeo
Venue: SIAM Journal on Discrete Mathematics (2000)

We introduce two new classes of graphs which we call convex-round, respectively concave-round graphs. Convex-round (concave-round) graphs are those graphs whose vertices can be circularly enumerated so that the (closed) neighborhood of each vertex forms an interval in the enumeration. Hence the two classes transform into each other by taking complements. We show that both classes of graphs have nice structural properties. We observe that the class of concave-round graphs properly contains the class of proper circular arc graphs and, by a result of Tucker [ Pacific J. Math., 39 (1971), pp. 535--545], is properly contained in the class of general circular arc graphs. We point out that convex-round and concave-round graphs can be recognized in O(n+m) time (here n denotes the number of vertices and m the number of edges of the graph in question). We show that the chromatic number of a graph which is convex-round (concave-round) can be found in time O(n+m) (O(n2)). We describe optimal O(n+m) time algorithms for finding a maximum clique, a maximum matching, and a Hamiltonian cycle (if one exists) for the class of convex-round graphs. Finally, we pose a number of open problems and conjectures concerning the structure and algorithmic properties of the two new classes and a related third class of graphs.
Resource Management for Fault Tolerant PathStructures in SONET Ring Networks
Authors: Wayne D. Grover
Venue: Journal of Network and Systems Management (1999)

There is growing interest on the part of network operators in the ability to analyze the availability of path implementations in their networks and to provide various grades of assured service availability to customers. The calculation of availability is, however, considerably more complex in today's SONET ring-based networks than in prior point-to-point systems. This is due both to the active protection nature of the rings and their dual-redundant interconnect strategies. We show that there is also more than one option for dual-ring interconnection and that a minimum cost high availability path implementation will generally involve a mixture of matched-node and explicitly dual fed treatments. We develop an economic comparison of dual feeding (df) and matched nodes (mn) in terms of the resource consumption of each scheme and show that the choice can be made on an individual ring-by-ring basis with a simple decision criterion. We then develop expressions of general use for the end-to-end unavailability of single-fed, pure df, mn and mixed df-mn path constructions. These results are a step towards on-line provisioning or path planning systems that can minimize the path implementation cost subject to an assured target level of design availability.
Robustness of Nonlinear Filters Over the Infinite Time Interval
Authors: Amarjit Budhiraja, Harold J. Kushner
Venue: SIAM Journal on Control and Optimization (1998)

Nonlinear filtering is one of the classical areas of stochastic control. From the point of view of practical usefulness, it is important that the filter not be too sensitive to the assumptions made on the initial distribution, the transition function of the underlying signal process and the model for the observation. This is particularly acute if the filter is of interest over a very long or potentially infinite time interval. Then the effects of small errors in the model which is used to construct the filter might accumulate to make the output useless for large time. The problem of asymptotic sensitivity to the initial condition has been treated in several papers. We are concerned with this as well as with the sensitivity to the signal model, uniformly over the infinite time interval. It is conceivable that the effects of even small errors in the model will accumulate so that the filter will eventually be useless. The robustness is shown for three classes of problems. For the first two cases, the signal model is Markov and the observations are taken in discrete time, and the observation is the usual function of the signal plus noise. The last class treated is a continuous time Markov process, with a point process observation.
Sufficient Conditions for Regularity and Singularity of Interval Matrices
Authors: Georg Rex, Jiri Rohn
Venue: SIAM Journal on Matrix Analysis and Applications (1999)

Several verifiable sufficient conditions for regularity and singularity of interval matrices are given. As an application, a verifiable sufficient condition is derived for an interval matrix to have all eigenvalues real.
The state of academic hiring in computer science: and interim review
Authors: J. Paul Myers,  Jr., Henry M. Walker
Venue: ACM SIGCSE Bulletin (1998)

This article reports the results of several surveys, which examine current conditions for hiring computing (CS, CIS) faculty. Specifically, the article takes a broad look at some statistics in the most recent Taulbee Survey [1, 2] and also reports on three surveys, conducted by the authors, utilizing the mailing list. Each of these instruments gives only a limited picture, but their results seem consistent and point to a remarkable under supply of candidates. While people may speculate about the short-term consequences of this shortage, all results point to a long-term need to strongly encourage students to enter academia careers in computer science.
Developing services for open eprint archives: globalisation, integration and the impact of links
Authors: Steve Hitchcock, Les Carr, Zhuoan Jiao, Donna Bergmark, Wendy Hall, Carl Lagoze, Stevan Harnad
Venue: Proceedings of the fifth ACM conference on Digital libraries (2000)

The rapid growth of scholarly information resources available in electronic form and their organisation by digital libraries is proving fertile ground for the development of sophisticated new services, of which citation linking will be one indispensable example. Many new projects, partnerships and commercial agreements have been announced to build citation linking applications. This paper describes the Open Citation (OpCit) project, which will focus on linking papers held in freely accessible eprint archives such as the Los Alamos physics archives and other distributed archives, and which will build on the work of the Open Archives initiative to make the data held in such archives available to compliant services. The paper emphasises the work of the project in the context of emerging digital library information environments, explores how a range of new linking tools might be combined and identifies ways in which different linking applications might converge. Some early results of linked pages from the OpCit project are reported.
Lotsizing and Scheduling on Parallel Machines with Sequence-Dependent Setup Costs
Authors: Sungmin Kang, Kavindra Malik, L. Joseph Thomas
Venue: Management Science (1999)

Industrial lotsizing and scheduling pose very difficult analytical problems. We propose an unconventional model that deals with sequence-dependent setup costs in a multiple-machine environment. The sequence-splitting model splits an entire schedule into subsequences, leading to tractable subproblems. An optimization approach based on a column generation/branch and bound methodology is developed, and heuristically adapted to test problems including five real-world problem instances gathered from industry.
Fostering civil associations in Africa through GOVERNET: an administrative reform network
Authors: Sajda Qureshi
Venue: Information Technology for Development (1998)

The use of electronic communications technology in the developing world context brings forth challenges that may potentially unleash the power of civil society by fostering networking among civil servants involved in public administration reform. This paper highlights the key considerations that drive the need for building civil associations through networks and explores the development of GOVERNET, an administrative reform network and concludes with some insight into the salient issues driving this form of networking.
FunState&mdash;an internal design representation for codesign
Authors: L. Thiele, K. Strehl, D. Ziegenbein, R. Ernst, J. Teich
Venue: Proceedings of the 1999 IEEE/ACM international conference on Computer-aided design (1999)

In this paper, an internal design model called FunState (functions driven by state machines) is presented that enables the representation of different types of system components and scheduling mechanisms using a mixture of functional programming and state machines.It is shown here how properties relevant for scheduling and verification of specification models like boolcan dataflow, cyclostatic dataflow, synchronous dataflow, marked graphs, and communicating state machines as well as Petri nets may be represented in the FunState model. Examples of methods suited for FunState are described, such as scheduling and verification. They are based on the representation of the model's state transitions in form of a periodic graph.
Matrices with Identical Sets of Neighbors
Authors: Imre Barany, Herbert Scarf
Venue: Mathematics of Operations Research (1998)

Given a generic m by n matrix A, a lattice point h in n is a neighbor of the origin if the body {x: Ax &#8804; b}, with bi = max{0, aih}, i = 1,...,m, contains no lattice point other than 0 and h. The set of neighbors, N(A), is finite and 0-symmetric. We show that if A' is another matrix of the same size with the property that sign aih = sign ai'h for every i and every h &#949; N(A), then A' has precisely the same set of neighbors as A. The collection of such matrices is a polyhedral cone, described by a finite set of linear inequalities, each such inequality corresponding to a generator of one of the cones Ci = pos{h &#949; N(A): aih Ci has "few" generators. We demonstrate this in the first nontrivial case n = 3, m = 4.
Instruction path coprocessors
Authors: Yuan Chou, John Paul Shen
Venue: ACM SIGARCH Computer Architecture News (2000)

This paper presents the concept of an Instruction Path Coprocessor (I-COP), which is a programmable on-chip coprocessor, with its own mini-instruction set, that operates on the core processor's instructions to transform them into an internal format that can be more efficiently executed. It is located off the critical path of the core processor to ensure that it does not negatively impact the core processor's cycle time or pipeline depth. An I-COP is highly versatile and can be used to implement different types of instruction transformations to enhance the IPC of the core processor. We study four potential applications of the I-COP to demonstrate the feasibility of this concept and investigate the design issues of such a coprocessor. A prototype instruction set for the I-COP is presented along with an implementation framework that facilitates achieving high I-COP performance. Initial results indicate that the I-COP is able to efficiently implement the trace cache fill unit as well as the register move, stride data prefetching and linked data structure prefetching trace optimizations.
Automating parallel simulation using parallel time streams
Authors: Victor Yau
Venue: ACM Transactions on Modeling and Computer Simulation (TOMACS) (1999)

This paper describes a package for parallel steady-state stochastic simulation that was designed to overcome problems caused by long simulation times experienced in our ongoing research in performance evaluation of high-speed and integrated-services communication networks, while maintaining basic statistical rigors of proper analysis of simulation output data. The package, named AKAROA, accepts ordinary (nonparallel) simulation programs, and alll further stages of stochastic simulation should be transparent for users. The package employs a new method of sequential estimation for the Multiple-Replications-in-Parallel scenario. All basic functions, including the transformation of originally nonparallel simulators into ones suitable for parallel execution, control of the precision of estimates, and stopping of parallel simulation processes when the required precision of the overall steady-state estimates is achieved, are automated. The package can be used on multiprocessor systems and/or heterogeneous computer networks, involving an arbitrary number of processors. The design issues, architecture, and implementation of AKAROA, as well as the results of its preliminary performance studies are presented
An evaluation of audio-centric CMU wearable computers
Authors: Asim Smailagic
Venue: Mobile Networks and Applications (1999)

Carnegie Mellon's Wearable Computers project is defining the future for not only computing technologies but also for the use of computers in daily activities. Fifteen generations of CMU's wearable computers are evolutionary steps in the quest for new ways to improve and augment the integration of information in the mobile environment. The complexity of their architectures has increased by a factor of over 200, and the complexity of the applications has also increased significantly. In this paper, we provide a taxonomy of their capabilities and evaluate the performance of audio-centric CMU wearable computers.
Compilability and compact representations of revision of Horn knowledge bases
Authors: Paolo Liberatore
Venue: ACM Transactions on Computational Logic (TOCL) (2000)

Several methods have been proposed as an attempt to deal with dynamically changing scenarios. From a computational point of view, different formalisms have different computational properties. In this article we consider knowledge bases represented as sets of Horn clauses. The importance of this case is twofold: first, inference is polynomial, thus tractable; second, Horn clauses represents causal relations between facts, thus they are of great practical importance, although not all propositional knowledge bases can be represented in Horn form. The complexity of Horn revision is still high, and in some cases coincides with the complexity of the general (non-Horn) case. We analyze the complexity of belief revision from the point of view of the compilation [Cadoli et al. 1999]: we study the possibility of reducing the complexity by allowing a (possibly expensive) preprocessing of part of the input of the problem. Extending the work of Cadoli et al.[1996], we consider the problem of compact representation of revision in the Horn case, i.e., given a knowledge base T and an update P (both represented by Horn clauses) decide whether T * P, the result of the revision, can be represented with a propositional formula whose size is polynomial in the size of T and P. We give this representation for all formalisms for which it exists, and we show that the existence of a compact representation is related to the possibility of decreasing the complexity of a formalism via a proprocessing.
Secondary Data Bases and Their Use in Outcomes Research: A Review of the Area Resource File and the Healthcare Cost and Utilization Project
Authors: Andrea Erickson Best
Venue: Journal of Medical Systems (1999)

Secondary data sources are being used more frequently than ever in outcomes research. The speed and relative low cost of these data bases makes them ideal for analyzing outcomes. Today's researcher has numerous secondary data bases available for use. Few publications exist to help researchers locate the ideal data set for their needs. Herein, two national secondary data bases are reviewed: the Area Resource File (ARF) and the Healthcare Cost and Utilization Project (HCUP). These two data sets represent the two types of secondary data: aggregate and individual. ARF represents an aggregate data set and HCUP represents an individual data set. The advantages of each type of secondary data will also be reviewed.
Asynchronous scheduling of redundant disk arrays
Authors: Peter Sanders
Venue: Proceedings of the twelfth annual ACM symposium on Parallel algorithms and architectures (2000)

Random redundant allocation of data to parallel disk arrays can be exploited to achieve low access delays. New algorithms are proposed which improve the previously known shortest queue algorithm by systematically exploiting that scheduling decisions can be deferred until a block access is actually started on a disk. These algorithms are also generalized for coding schemes with low redundancy. Using extensive experiments, practically important quantities are measured which have so far eluded an analytical treatment: The delay distribution when a stream of requests approaches the limit of the system capacity, the system efficiency for parallel disk applications with bounded prefetching buffers, and the combination of both for mixed traffic. A further step towards practice is taken by outlining the system design for &agr;: automatically load-balanced parallel hard-disk array.
An Algorithm that Learns What&lsquo;s in a Name
Authors: Daniel M. Bikel, Richard Schwartz, Ralph M. Weischedel
Venue: Machine Learning (1999)

In this paper, we present IdentiFinderTM, a hidden Markov model that learns to recognize and classify names, dates, times, and numerical quantities. We have evaluated the model in English (based on data from the Sixth and Seventh Message Understanding Conferences [MUC-6, MUC-7] and broadcast news) and in Spanish (based on data distributed through the First Multilingual Entity Task [MET-1]), and on speech input (based on broadcast news). We report results here on standard materials only to quantify performance on data available to the community, namely, MUC-6 and MET-1. Results have been consistently better than reported by any other learning algorithm. IdentiFinder&lsquo;s performance is competitive with approaches based on handcrafted rules on mixed case text and superior on text where case information is not available. We also present a controlled experiment showing the effect of training set size on performance, demonstrating that as little as 100,000 words of training data is adequate to get performance around 90% on newswire. Although we present our understanding of why this algorithm performs so well on this class of problems, we believe that significant improvement in performance may still be possible.
Galerkin Projection Methods for Solving Multiple Linear Systems
Authors: Tony F. Chan, Michael K. Ng
Venue: SIAM Journal on Scientific Computing (1999)

In this paper, we consider using conjugate gradient (CG) methods for solving multiple linear systems $A^{(i)} x^{(i)} = b^{(i)},$ for $1 \le i \le s,$ where the coefficient matrices $A^{(i)}$ and the right-hand sides $b^{(i)}$ are different in general.\ In particular, we focus on the seed projection method which generates a Krylov subspace from a set of direction vectors obtained by solving one of the systems, called the seed system, by the CG method and then projects the residuals of other systems onto the generated Krylov subspace to get the approximate solutions.\ The whole process is repeated until all the systems are solved.\ Most papers in the literature [T.\ F.\ Chan and W.\ L.\ Wan, {\it SIAM J.\ Sci.\ Comput.}, 18 (1997), pp.\ 1698--1721; B.\ Parlett {\it Linear Algebra Appl.}, 29 (1980), pp.\ 323--346; Y.\ Saad, {\it Math.\ Comp.}, 48 (1987), pp.\ 651--662; V.\ Simoncini and E.\ Gallopoulos, {\it SIAM J.\ Sci.\ Comput.}, 16 (1995), pp.\ 917--933; C.\ Smith, A.\ Peterson, and R.\ Mittra, {\it IEEE Trans.\ Antennas and Propagation}, 37 (1989), pp. 1490--1493] considered only the case where the coefficient matrices $A^{(i)}$ are the same but the right-hand sides are different.\ We extend and analyze the method to solve multiple linear systems with varying coefficient matrices and right-hand sides. A theoretical error bound is given for the approximation obtained from a projection process onto a Krylov subspace generated from solving a previous linear system. Finally, numerical results for multiple linear systems arising from image restorations and recursive least squares computations are reported to illustrate the effectiveness of the method.
Block-Boundary Value Methods for the Solution of Ordinary Differential Equations
Authors: F. Iavernaro, F. Mazzia
Venue: SIAM Journal on Scientific Computing (1999)

Block-boundary value methods are considered and applied to solve initial value problems. Results on their convergence and stability properties are presented and their intermediate position between the class of multistep and Runge--Kutta methods is established.
Solving Local Cost Estimation Problem for Global Query Optimization in Multidatabase Systems
Authors: Qiang Zhu, Per-åke Larson
Venue: Distributed and Parallel Databases (1998)

To meet users&lsquo; growing needs for accessing pre-existing heterogeneous databases, a multidatabase system (MDBS) integrating multiple databases has attracted many researchers recently. A key feature of an MDBS is local autonomy. For a query retrieving data from multiple databases, global query optimization should be performed to achieve good system performance. There are a number of new challenges for global query optimization in an MDBS. Among them, a major one is that some local optimization information, such as local cost parameters, may not be available at the global level because of local autonomy. It creates difficulties for finding a good decomposition of a global query during query optimization. To tackle this challenge, a new query sampling method is proposed in this paper. The idea is to group component queries into homogeneous classes, draw a sample of queries from each class, and use observed costs of sample queries to derive a cost formula for each class by multiple regression. The derived formulas can be used to estimate the cost of a query during query optimization. The relevant issues, such as query classification rules, sampling procedures, and cost model development and validation, are explored in this paper. To verify the feasibility of the method, experiments were conducted on three commercial database management systems supported in an MDBS. Experimental results demonstrate that the proposed method is quite promising in estimating local cost parameters in an MDBS.
GRASP: A Search Algorithm for Propositional Satisfiability
Authors: João P. Marques-Silva, Karem A. Sakallah
Venue: IEEE Transactions on Computers (1999)

This paper introduces GRASP (Generic seaRch Algorithm for the Satisfiability Problem), a new search algorithm for Propositional Satisfiability (SAT). GRASP incorporates several search-pruning techniques that proved to be quite powerful on a wide variety of SAT problems. Some of these techniques are specific to SAT, whereas others are similar in spirit to approaches in other fields of Artificial Intelligence. GRASP is premised on the inevitability of conflicts during the search and its most distinguishing feature is the augmentation of basic backtracking search with a powerful conflict analysis procedure. Analyzing conflicts to determine their causes enables GRASP to backtrack nonchronologically to earlier levels in the search tree, potentially pruning large portions of the search space. In addition, by ¿recording¿ the causes of conflicts, GRASP can recognize and preempt the occurrence of similar conflicts later on in the search. Finally, straightforward bookkeeping of the causality chains leading up to conflicts allows GRASP to identify assignments that are necessary for a solution to be found. Experimental results obtained from a large number of benchmarks indicate that application of the proposed conflict analysis techniques to SAT algorithms can be extremely effective for a large number of representative classes of SAT instances.