ppxscal/embedding_network huggingface dataset:
Collecting Coupons on Trees, and the Analysis of Random Walks
Authors: U. Feige
Venue:  (1993)

We consider the cover time E>sub<u>/sub<G\), the expected time it takes a random walk that starts at u to visit all n vertices of a connectedgraph G. By combining a minimum wieght spanning tree argument with a coupon collector argument, we obtainE>sub<u>/sub<G\) 1 2(_T)WT\)\)+_v GDu,v\)\)) where WT\) is the weight of spanning tree T, and Du,v= Hu,v-Hv,u) is the difference between the expected time it takes a random walk to hit v, and the expected time it takes it to afterwards get back to u. We use this bound to show: max>sub<G>/sub<min>sub<u>/sub<E>sub<u>/sub<G\)=(1+o(1))2n^3/27. This answers an open questionof Aldous.\pointThe n-path is the n-vertex tree on which the cover time is maximized. This confirms a conjecture of Brightwell and Winkler.\pointFor regular graphs, E_uG>2n^2. This improves the leadingconstant in previously known upper bounds.\endlistWe also provide upper bouhnds on E^+_uG, the expected timeto cover G and return to u The ACM Portal is published by the Association for Computing Machinery. Copyright © 2010 ACM, Inc. Terms of Usage Privacy Policy Code of Ethics Contact Us Useful downloads: Adobe Acrobat QuickTime Windows Media Player Real Player
Rotation of Polygonal Space Structures
Authors: C. Y. Wang, Layne T. Watson
Venue:  (1990)

The free rotation in space of flexible polygonal structures about their axes is studied. The large deformation equations are formulated, resulting in a set of sixth order nonlinear differential equations. The governing parameter B represents the relative importance of centrifugal forces to flexural rigidity. Perturbation solutions are obtained for small B. The equations are also integrated numerically by quasi-Newton and homotopy methods. Forces, moments, and maximum deformations are determined for polygons of three to six sides and B up to 100. At very large B, the polygons deform into a circle.
Using Belbin''s Role to Improve Team Effectiveness
Authors: Stevens K. Todd, Henry Sallie M.
Venue:  (1997)

This paper presents a controlled experiment conducted with software engineering students that demonstrates the utility of forming teams based on R. Meredith Belbin''s set of team roles. The overall research effort is a demonstration of the general utility of Belbin''s roles in improving the effectiveness of teams, even industry teams. The significance of this work is twofold: performance and team viability. Performance improvements clearly improve a team''s productivity; viability issues are important because if employees remain with a team or employer, then employee replacement costs are reduced. To address this problem, as an initial step, controlled experiments have been conducted to demonstrate that teams that contain certain roles perform better than teams that do not. In a laboratory setting, a number of teams were formed that contained a single leader; other teams were formed that had no leader or multiple leaders. The results of this single experiment are positive. They demonstrate that indeed Belbin''s roles are useful knowledge in forming teams. The specific conclusion of this first controlled experiment is that a single leader on a team perform better than having multiple leaders or no leader. In other words, as one would expect, the mean time to completion for the leaderless group of teams was significantly larger than the group of teams with leaders. This means that Belbin''s roles can be utilized in team formation, making sure that a team has a single leader, and also for evaluation on extant teams. Both of these aspects, formation and evaluation, are extremely useful to managers of software programmers.
Static Virtual Types in Java Layers
Authors: Richard Cardone, Calvin Lin
Venue:  (2000)

This specification describes how a simple, static form of virtual typing can be implemented in a parametrically polymorphic version of Java. We discuss the need for virtual types and the tradeoffs of integrating virtual types into a statically typed, object-oriented language. Though our discussion is couched in terms of Java Layers, the design can be used in more general settings.
Efficient Disk Allocation for Fast Similarity Searching
Authors: Sunil Prabhakar, Divyakant Agrawal, Amr El Abbadi
Venue:  (1997)

As databases increasingly integrate non-textual information it is becoming necessary to support efficient similarity searching in addition to range searching. Recently, declustering techniques have been proposed for improving the performance of similarity searches through parallel I/O. In this paper, we propose a new scheme which provides good declustering for similarity searching. In particular, it does global declustering as opposed to local declustering, exploits the availability of extra disks and does not limit the partitioning of the data space. Our technique is based upon the cyclic declustering schemes which were developed for range and partial match queries. We establish, in general, that cyclic declustering techniques outperform previously proposed techniques.
TIMING-DRIVEN FLOORPLANNING WITH INTERMEDIATE BUFFER INSERTION
Authors: Maggie Z. Kang, Wayne W. Dai, Tom Dillinger, David LaPotin
Venue:  (1997)

As the devices and lines shrink into the deep submicron range, it is more effective to insert the intermediate buffers rather than to widen the wires. Almost all existing timing driven floorplanning and placement algorithms and tools don''t consider the option of buffer insertion, so many good solutions with smaller area and better routability may be unnecessarily excluded. In this paper, we propose a new methodology of floorplanning and placement where buffered trees are used to estimate the wiring delay. Instead of treating the delay as one of the objectives as done by most of the previous works, we formulate the Delay Bounded Minimum Buffered Tree (DBMB-tree) as follows: given a net and delay bounds associated with critical terminals, construct a tree with intermediate buffers inserted to minimize the total wiring length while satisfying the given delay bounds. Based on the Elmore delay model, we propose an efficient algorithm to construct DBMB-tree for floorplanning and placement. Experiment results show that using buffer insertion at the floorplanning and placement stage yields significantly better solutions in terms of both chip area and total wire length. Existing multi-objective floorplanning tools use weighted cost summation subject to user-defined constraints to evaluate the solution. It is difficult, if not impossible, to derive a set of weight values from the vaguely defined multiple objectives and the optimization results are very sensitive to the choice of the weight values. Multi-dimension cost vector is introduced to represent the cost value for each objective explicitly by H. Esbensen. We define the acceptance function in multiple dimensions based on the votes of invited experts, and order the objectives by their sensitivities. Multiple objectives are introduced gradually during the optimization process. The experiment results demonstrate the efficiency of the approach.
CATEGORIZATION OF MACROMOLECULAR SEQUENCES BY MINIMAL LENGTH ENCODING (Ph.D. Thesis)
Authors: Aleksandar D Milosavljevic
Venue:  (1990)

A new method for categorization of macromolecular sequences is developed by applying the Minimal Length Encoding principle. While the method is developed with the particular application in mind, the formal model may be applied to any categorization problem where the observations can be represented by using a finite set of attributes that take values from a finite set. The proposed method is shown to be more general than the categorization procedures based on Weighted Parsimony and Compatibility principles. The proposed method also provides a principled tradeoff between the number of inferred classes and their fit to data. A statistical significance test for the presence of classes is also proposed. The categorization problem is proven to be computationally hard even under various simplifying assumptions. To avoid the excessive computation time, an algorithm that is based on a local search strategy is proposed. The algorithm was applied to rediscover several known macromolecular sequence families as well as to discover new classes of Bacteriophage T7 promoters and Alu sequences. The algorithm was also tested on simulated data to determine the range of data parameters where it categorizes the sequences correctly. While the application of the Minimal Length Encoding principle was restricted to the categorization of macromolecules, a very general background on the process of categorization and the Minimal Length Encoding principle is also provided. It is proposed that categorization, and perhaps inductive inference in general, can be viewed as a process of minimal length encoding of observations.
Topics in Survivable Systems
Authors: John C. Knight, Matthew C. Elder, A. C. Chapin, Brownell K. Combs, Steven Geist, Sean McCulloch, Luis G. Nakano, Robert S. Sielken
Venue:  (1998)

In the Spring of 1998, a special topics course in Information Survivability was taught at the University of Virginia. The attendees were graduate students in computer science and the instructor for the course was John C. Knight. This report is a compendium of papers written by students who attended the course. The topics covered in this report are not comprehensive by any means; the survivability area is too broad for that. The papers do, however, span quite a wide technical range. The first paper, by Robert S. Sielken, is entitled "The Public Switched Telephone Network". This is a short summary of many aspects of the telephone system and provides some background information about how one of the critical infrastructure systems works. The second paper, by Sean McCulloch, is entitled "An Analysis of Non-Security Failures of the Electric, Phone, and Air Traffic Systems". This is an examination of some of the incidents that have occurred in these infrastructure application domains. The limitation to non-security incidents is important because it helps to point out the many sources of failure to which these systems are subject. The general concern of the community about security is significant, and four of the papers cover security-related topics. The first, by Matthew C. Elder, is entitled "Major Security Attacks on Critical Infrastructure Systems". This paper discusses recent security attacks on critical information systems, and presents extensive information about the severity of the security problem. The second security paper, by Brownell K. Combs, is entitled "Hacking Information Available on the Internet". This paper examines the material available to hackers on the Internet. The author sought out sources of information so as to determine what is available and how easy it is to obtain. The results are surprising. The third security paper, by Steven Geist, is entitled "Firewalls". This paper presents a summary report on firewalls, an important technology designed to help improve the security of existing systems. The fourth paper, by Luis Nakano, is entitled "State of the Art in Computer Virus Prevention". Viruses are growing in number at an extraordinary rate and many new techniques are being developed by their authors to combat existing detection systems. In this paper, the different types of virus are summarized and approaches to their elimination discussed. The final paper in this report is by A. C. Chapin and is entitled "Smart Cards: Security in the New Transaction Cards". The field of critical information systems is changing rapidly and this final paper is about an emerging technology that will have a large impact on all aspects of the field in the future. These papers have been compiled into this report to provide a ready source of information on a variety of topics for the interested reader. In each case, the papers include an extensive bibliography that can be used to obtain more details about the subject of the paper. For more informati
Extracting Blobs from Raster Images
Authors: Patrick C Hew
Venue:  (1995)

If an human being were presented with a picture of some jelly beans, he would probably be able to identify where they were, count the number present, and estimate the size of each. Furthermore, he could do so if the jelly beans were replaced with cancer cells, highly magnified oxide particles, or other kinds of blobs - even if he had never seen such objects before. It is desirable to match this capability with a machine, and this dissertation presents three approaches from contemporary research. The first is template matching, where we are able to approximately describe a priori the blobs which we seek. We then consider Mathematical Morphology, trying to separate clusters of overlapping blobs to yield an easier problem. We end with edge grouping, collecting pixels on the edges of the blobs into natural contours, using the linear Kalman Filter. The research is motivated by a study of images provided by the UWA Centre for Microscopy and Microanalysis, for the automated inspection of titanium dioxide particles in paint additives. There is also discussion about the detection of cancer cells in cytology images, and of algal cells in water.
A Secure Group Key Management Communication Lower Bound
Authors: Y. R Yang, Simon S. Lam
Venue:  (2000)

We discuss in this paper a llower bound on communication cost for secure group key management system. To model the rekeying process, we introduce the concept of rekey encryption graphs. Using the rekey encryption graphs, we show that there exists a sequence of join and leave requests such that the amortized per request communication cost is "omega"(ln(n)), where n is the number of users who have ever joined the secure group.
Genetic algorithms and timetabling
Authors: Peter Ross, Emma Hart, Dave Corne
Venue: Advances in evolutionary computing: theory and applications (2003)

This chapter discusses the state of the art, at the start of the new millennium, in using evolutionary algorithms to tackle timetabling problems of various kinds. Timetabling problems are interesting because they are often regarded as difficult examples of problems which mix hard and soft constraints, and yet huge numbers of practical instances need to be tackled somehow.A variety of representations and algorithms have been used, but there is still a need for more wide-ranging scientific study to compare different approaches. Most authors merely report success of some kind on the problems that occur at their own institutions.
From Watson-Crick L systems to Darwinian P systems
Authors: Erzsébet Csuhaj-Varjú, Carlos Martín-Vide, Gheorgh Păaun, Arto Salomaa
Venue: Natural Computing: an international journal (2003)

Watson-Crick L systems are language generating devices making use of Watson-Crick complementarity, a fundamental concept of DNA computing. These devices are Lindenmayer systems enriched with a trigger for complementarity transition: if a ``bad'' string is obtained, then the derivation continues with its complement which is always a ``good'' string. Membrane systems or P systems are distributed parallel computing models which were abstracted from the structure and the way of functioning of living cells. In this paper, we first interpret the results known about the computational completeness of Watson-Crick E0L systems in terms of membrane systems, then we introduce a related way of controlling the evolution in P systems, by using the triggers not in the operational manner (i.e., turning to the complement in a ``bad'' configuration), but in a ``Darwinian'' sense: if a ``bad'' configuration is reached, then the system ``dies'', that is, no result is obtained. The triggers (actually, the checkers) are given as finite state multiset automata. We investigate the computational power of these P systems. Their computational completeness is proved, even for systems with non-cooperative rules, working in the non-synchronized way, and controlled by only two finite state checkers; if the systems work in the synchronized mode, then one checker for each system suffices to obtain the computational completeness.
Synthesis-Oriented Situational Analysis in User Interface Design
Authors: Kevin A. Mayo, H. R Hartson
Venue:  (1993)

Analytic evaluation is a term describing a class of techniques for examining a representation of a user interface design, discovering design flaws and/or predicting user task performance. In our work with analytic evaluation, we have observed limitations on the effectiveness and efficiency of analytic techniques for formative evaluation supporting the iterative design and re-design cycle. Here we support those observations with arguments based on theoretical limitations of the models underlying these techniques. By way of comparison we discuss desirable characteristics for an alternative approach. In our search for such an alternative, we have developed the Task Mapping Model, a substantively different approach to analysis for supporting the user interface design. We briefly describe the Task Mapping Model and give some examples illustrating its desirable characteristics.
An Introduction to the Multiresolution Fourier Transform and its Applications
Authors: R. G. Wilson, A. D. Calway, E. R.S. Pearson, A. R. Davies
Venue:  (1992)

The Multiresolution Fourier Transform (MFT) is a new tool for signal analysis which is designed with the express intent of providing a local signal representation adapted to the problem of segmenting signals into s set of meaningful primitive features. It is shown that this requires a signal representation that is richer than conventional Short Time Fourier Transforms (STFT) or indeed Wavelet Transformations (WT), but shares with them the property of giving a phase-space description of the signal. These considerations lead to the new transform, which can be seen as a marriage of the STFT and WT which overcomes the limitations of either as a signal representation for segmentation. Some of the elementary properties of the MFT are then discussed and its implementation for discrete signals is considered. The report is concluded with a summary of results obtained with the MFT on audio and image signal segmentation.
Random Walks on Regular and Irregular Graphs
Authors: D. Coppersmith, U. Feige, J. Shearer
Venue:  (1993)

We consider simple random walks on undirected graphs. We show that the cyclic cover time of any connected graph is Q(n2 d>sub<ave>/sub< (d-1)>sub<ave>/sub<), where n is the number of vertices in the graph, d>sub<ave>/sub< is the average degree of its vertices, and (d-1)>sub<ave>/sub< is the average of the inverse of the degree of its vertices. Our proof solves a conjecture regarding minimum resistance spanning trees of graphs, improves previously obtained bounds regarding the cover time of graphs, and provides an alternative proof that the maximum commute time in any graph is at most 4n3/27 + o(n3).
Finding Optimal Targets for Change Agents: A Computer Simulation of Innovation Diffusion
Authors: Dirk Maienhofer, Thomas Finholt
Venue: Computational Mathematical Organization Theory (2002)

We introduce a diffusion of innovation model based on a network threshold approach. Realistic network and threshold data were gathered regarding the diffusion of new software tools within part of a large organization. Novel model features are a second threshold for innovation rejection and a memory that allows actors to take trends into account. Computer simulations produce expected outcomes, such as the S-shaped diffusion curve, but also diffusion breakdown and oscillations. We define and compute the quality of change agent targets in terms of the impact targeted actors have on the diffusion process. Our simulations reveal considerable variance in the quality of actors as change agent targets. Certain actors can be singled out as especially important to the diffusion process. Small changes in the distribution of thresholds and changes in some parameters, such as the sensitivity for trends, lead to significant changes in the target quality measure. To illustrate these interdependencies we outline how the impact of an actor targeted by a change agent spreads through the network. We thus can explain why a good change agent target does not necessarily need to be an opinion leader. Simulations comparing the effectiveness of randomly selected targets versus a group of good change agent targets indicate that the selection of good targets can accelerate innovation diffusion.
STOCHASTIC CONTEXT-FREE GRAMMARS FOR MODELLING RNA
Authors: Yasubimi Sakakibara, Michael Brown, Rebecca C. Underwood, I. S Mian, David Haussler
Venue:  (1993)

Stochastic context-free grammars (SCFGs) are applied to the problems of folding, aligning and modeling families of homologous RNA sequences. These models capture the common primary and secondary structure of the sequences with a context-free grammar, much like those used to define the syntax of programming languages. SDFGs generalize the hidden Markov models used in related work on protein and DNA sequences. The novel aspect of this work is that the SCFGs developed here are learned automatically from initially unaligned and unfolded training sequences. To do this, a new generalization of the forward- backward algorithm, commonly used to train hidden Markov models, is introduced. This algorithm is based on tree grammars, and is more efficient than the inside-outside algorithm, which was previously proposed to train SCFGs. This method is tested on the family of transfer RNA (tRNA) sequences. The results show that the model is able to reliably discriminate tRNA sequences from other RNA sequences of similar length, that it can reliably determine the secondary structure of new tRNA sequences, and that it can produce accurate multiple alignments of large collections of tRNA sequences. The model is also extended to handle introns present in tRNA genes.
A Study of the Allocation Behavior of the SPECjvm98 Java Benchmarks
Authors: Sylvia Dieckmann, Urs Hoelzle
Venue:  (1998)

We present an analysis of the memory usage for six of the Java programs in the SPECjvm98 benchmark suite. Most of the programs are real-world applications with high demands on the memory system. For each program, we measured as much low level data as possible, including age and size distribution, type distribution, thread-local objects, and the overhead of object alignment. Among other things, we found that non-pointer data usually represents more than 50% of the allocated space for instance objects, that Java objects are fairly small, and that a large fraction of objects is never accessible outside the thread that allocated it.
HOW WELL DO BAYES METHODS WORK FOR ON-LINE PREDICTION OF {+- 1} VALUES?
Authors: David Haussler, A. Barron
Venue:  (1992)

We look at sequential classification and regression problems in which {+- 1}-labeled instances are given on-line, one at a time, and for each new instance, before seeing the label, the learning system must either predict the label, or estimate the probability that the label is +1. We look at the performance of Bayes method for this task, as measured by the total number of mistakes for the classification problem, and by the total log loss (or information gain) for the regression problem. Our results are given by comparing the performance of Bayes method to the performance of a hypothetical "omniscient scientist" who is able to use extra information about the labeling process that would not be available in the standard learning protocol. The results show that Bayes methods perform only slightly worse than the omniscient scientist in many cases. These results generalize previous results of Haussler, Kearns and Schapire, and Opper and Haussler.