Computer Sciences Commons^™

Incremental Evaluation Of Sliding- Window Queries Over Data Streams, T. M. Ghanem, M. Hammad, M. Mokbel, Walid G. Aref, Ahmed K. Elmagarmid

Department of Computer Science Technical Reports

No abstract provided.

Efficient Randomized Search Algorithms In Unstructured Peer-To-Peer Networks, Ronaldo A. Ferreira, Murali Krisna Ramanathan, Ananth Y. Grama, Suresh Jagannathan

Department of Computer Science Technical Reports

No abstract provided.

Janus: Towards Robust And Malicious Resilient Routing In Hybrid Wireless Networks, Bogdan Carbunar, Ioanis Ioannidis, Cristina Nita-Rotaru

Department of Computer Science Technical Reports

No abstract provided.

Quality-Aware Replication Of Multimedia Data, Yi-Cheng Tu, Sunil Prabhakar

Department of Computer Science Technical Reports

No abstract provided.

An Interactive Learning Environment For A Dynamic Educational Digital Library, Ee Peng Lim, Dion Hoe-Lian Goh, Yin-Leng Theng, Eng-Kai Suen

Research Collection School Of Computing and Information Systems

GeogDL is a digital library of geography examination resources designed to assist students in preparing for a national geography examination in Singapore. We describe an interactive learning environment built into GeogDL that consists of four major components. The practice and review module allows students to attempt individual examination questions, the mock exam provides a simulation of the actual geography examination, the trends analysis tool provides an overview of the types of questions asked in previous examinations, while the contributions module allows students and teachers to create and share knowledge within the digital library.

Incremental Policy Learning: An Equilibrium Selection Algorithm For Reinforcement Learning Agents With Common Interests, Nancy Fulda, Dan A. Ventura

Faculty Publications

We present an equilibrium selection algorithm for reinforcement learning agents that incrementally adjusts the probability of executing each action based on the desirability of the outcome obtained in the last time step. The algorithm assumes that at least one coordination equilibrium exists and requires that the agents have a heuristic for determining whether or not the equilibrium was obtained. In deterministic environments with one or more strict coordination equilibria, the algorithm will learn to play an optimal equilibrium as long as the heuristic is accurate. Empirical data demonstrate that the algorithm is also effective in stochastic environments and is able …

Bcl2 Translocation Defines A Unique Tumor Subset Within The Germinal Center B-Cell-Like Diffuse Large B-Cell Lymphoma, Javeed Iqbal, Warren G. Sanger, Andreas Rosenwald, Diane L. Pickering, Barbara Dave, Sandeep Dave, Li Xiao, Kahai Cao, Qiuming Zhu, Simon Sherman, Christine P. Hans, Dennis D. Weisenburger, Timothy C. Greiner, Randy D. Gascoyne, German Ott, H. Konrad Müller-Hermelink, Jan Delabie, Rita M. Braziel, Elaine S. Jaffe, Elias Campo, James C. Lynch, Joseph M. Conners, Julie M. Vose, James O. Armitage, Thomas M. Grogan, Louis M. Staudt, Wing C. Chan

Computer Science Faculty Publications

Gene expression profiling of diffuse large B-cell lymphoma (DLBCL) has revealed prognostically important subgroups: germinal center B-cell-like (GCB) DLBCL, activated B cell-like (ABC) DLBCL, and primary mediastinal large B-cell lymphoma. The t(14;18)(q32;q21) has been reported previously to define a unique subset within the GCB-DLBCL. We evaluated for the translocation in 141 cases of DLBCL that were successfully gene expression profiled. Using a dual-probe fluorescence in situ hybridization assay, we detected the t(14;18) in 17% of DLBCLs and in 34% of the GCB subgroup which contained the vast majority of positive cases. In addition, 12 t(14;18)-positive cases detected by polymerase chain …

Infosemm: Infosys It Security Maturity Model: A Report, Arcot Desai Narasimhalu, N. Dayasindhu, Raghavan Subramanian

Research Collection School Of Computing and Information Systems

Businesses are faced with a continuing battle related to cyber security related issues ranging from cyber attacks all the way to cyber (information) war. These issues affect result in information, system, reputation, and revenue related risks. These risks arise because of vulnerabilities introduced in three major parts of the enterprise – infrastructure, intelligence and practices. This report provides a rating system for representing the security health of enterprises.

Teabag: A Debugger For Curry, Stephen Lee Johnson

Dissertations and Theses

This thesis describes TeaBag, which is a debugger for functional logic computations. TeaBag is an accessory of a virtual machine currently under development. A distinctive feature of this machine is its operational completeness of computations, which places novel demands on a debugger. This thesis describes the features of TeaBag, in particular the handling of non-determinism, the ability to control nondeterministic steps, to remove context information, to toggle eager evaluation, and to set breakpoints on both functions and terms. This thesis also describes TeaBag's architecture and its interaction with the associated virtual machine. Finally, some debugging sessions of defective programs are …

Choosing A Starting Configuration For Particle Swarm Optimization, Mark Richards, Dan A. Ventura

Faculty Publications

The performance of Particle Swarm Optimization can be improved by strategically selecting the starting positions of the particles. This work suggests the use of generators from centroidal Voronoi tessellations as the starting points for the swarm. The performance of swarms initialized with this method is compared with the standard PSO algorithm on several standard test functions. Results suggest that CVT initialization improves PSO performance in high-dimensional spaces.

Task-Focused Summarization Of Email, Eric K. Ringger, Richard Campbell, Simon Corston-Oliver, Michael Gamon

Faculty Publications

We describe SmartMail, a prototype system for automatically identifying action items (tasks) in email messages. SmartMail presents the user with a task-focused summary of a message. The summary consists of a list of action items extracted from the message. The user can add these action items to their “to do” list.

An Empirical Investigation On End-Users’ Acceptance Of Enterprise Systems, Fiona Fui-Hoon Nah, Xin Tan, Soon Hing Teh

Research Collection School Of Computing and Information Systems

Despite the huge investments by organizations in ERP implementation, maintenance, and user training, ERP implementation failures and less-than-satisfactory productivity improvements are common. End-users’ reluctance or unwillingness to adopt or use the newly implemented ERP system is often cited as one of the main reasons for ERP failures. To examine factors leading to the lack of end-user acceptance of ERP systems, we reviewed the literature on user adoption of IT in mandatory contexts, developed hypotheses to explain ERP user acceptance, and conducted a survey study to test the hypotheses. In particular, we examined end-users’ attitudes toward system use and symbolic adoption, …

Notes On Equilibria In Symmetric Games, Shih-Fen Cheng, Daniel M. Reeves, Yevgeniy Vorobeychik, Michael P. Wellman

Research Collection School Of Computing and Information Systems

In a symmetric game, every player is identical with respect to the game rules. We show that a symmetric 2strategy game must have a pure-strategy Nash equilibrium. We also discuss Nash’s original paper and its generalized notion of symmetry in games. As a special case of Nash’s theorem, any finite symmetric game has a symmetric Nash equilibrium. Furthermore, symmetric infinite games with compact, convex strategy spaces and continuous, quasiconcave utility functions have symmetric pure-strategy Nash equilibria. Finally, we discuss how to exploit symmetry for more efficient methods of finding Nash equilibria.

Biased Support Vector Machine For Relevance Feedback In Image Retrieval, Steven Hoi, Chi-Hang Chan, Kaizhu Huang, Michael R. Lyu, Irwin King

Research Collection School Of Computing and Information Systems

Recently, support vector machines (SVMs) have been engaged on relevance feedback tasks in content-based image retrieval. Typical approaches by SVMs treat the relevance feedback as a strict binary classification problem. However, these approaches do not consider an important issue of relevance feedback, i.e. the unbalanced dataset problem, in which the negative instances largely outnumber the positive instances. For solving this problem, we propose a novel technique to formulate the relevance feedback based on a modified SVM called biased support vector machine (Biased SVM or BSVM). Mathematical formulation and explanations are provided for showing the advantages. Experiments are conducted to evaluate …

A Support-Ordered Trie For Fast Frequent Itemset Discovery, Ee Peng Lim, Yew-Kwong Woon, Wee-Keong Ng

Research Collection School Of Computing and Information Systems

The importance of data mining is apparent with the advent of powerful data collection and storage tools; raw data is so abundant that manual analysis is no longer possible. Unfortunately, data mining problems are difficult to solve and this prompted the introduction of several novel data structures to improve mining efficiency. Here, we critically examine existing preprocessing data structures used in association rule mining for enhancing performance in an attempt to understand their strengths and weaknesses. Our analyses culminate in a practical structure called the SOTrielT (support-ordered trie itemset) and two synergistic algorithms to accompany it for the fast discovery …

Reduced Index Sparse Representation In A Parallel Environment, Pedro Alfonso Escallon

Theses and Dissertations

Sparse-matrix/dense-vector multiplication algorithms are not as highly developed as algorithms for dense matrices. Dense matrix multiplication algorithms have been made efficient by exploiting data locality, parallelism, pipelining, and other types of optimization. Sparse matrix algorithms, on the other hand, encounter low or no data locality, indirect addressing, and no easy way to exploit parallelism. In an effort to achieve savings in storage and computational time, the topic of sparse matrix representation is often revisited. The first contribution of this thesis is the introduction of a new representation for sparse matrices. This representation is called here the Reduced Index Sparse (RIS) …

Knowledge Management Using Semantic Web Languages And Technologies, Steven J. Gollery, Jens G. Pohl

Collaborative Agent Design (CAD) Research Center

Each organization of more than a few persons generates a number of documents containing information about the activities of the organization. The sum of these documents provides a kind of organizational memory that can be used both in evaluations of past performance and as the basis of future planning based on previous experience.

Unfortunately, the nature of these documents mitigates against the reuse of information for purposes other than those for which each document was originally intended. To locate all the information about some aspect of the organization, it frequently becomes necessary for human beings to search a mass of …

Review Of The Product Development Process And Information Flow In The Manufacturing Industry: Problems And A Possible Wav Forward, E Opiyo

Tanzania Journal of Engineering and Technology (TJET)

No abstract provided.

Type-Safe Operating System Abstractions, Lea Wittie

Dartmouth College Ph.D Dissertations

Operating systems and low-level applications are usually written in languages like C and assembly, which provide access to low-level abstractions. These languages have unsafe type systems that allow many bugs to slip by programmers. For example, in 1988, the Internet Worm exploited several insecure points in Unix including the finger command. A call to finger with an unexpected argument caused a buffer overflow, leading to the shutdown of most Internet traffic. A finger application written in a type-safe language would have prevented its exploit and limited the points the Internet Worm could attack. Such vulnerabilities are unacceptable in security-critical applications …

Load Balancing Parallel Explicit State Model Checking, Rahul Kumar

Theses and Dissertations

This research first identifies some of the key concerns about the techniques and algorithms developed for distributed and parallel model checking; specifically, the inherent problem with load balancing and large queue sizes resultant in a static partition algorithm. This research then presents a load balancing algorithm to improve the run time performance in distributed model checking, reduce maximum queue size, and reduce the number of states expanded before error discovery. The load balancing algorithm is based on Generalized Dimension Exchange (GDE). This research presents an empirical analysis of the GDE based load balancing algorithm on three different supercomputing architectures---distributed memory …

Outdoor Experimental Comparison Of Four Ad Hoc Routing Algorithms, Robert S. Gray, David Kotz, Calvin Newport, Nikita Dubrovsky, Aaron Fiske, Jason Liu, Christopher Masone, Susan Mcgrath, Yougu Yuan

Computer Science Technical Reports

Most comparisons of wireless ad hoc routing algorithms involve simulated or indoor trial runs, or outdoor runs with only a small number of nodes, potentially leading to an incorrect picture of algorithm performance. In this paper, we report on the results of an outdoor trial run of four different routing algorithms, APRL, AODV, GPSR, and STARA, running on top of thirty-three 802.11-enabled laptops moving randomly through an athletic field. The laptops generated random traffic according to the traffic patterns observed in a prototype application, and ran each routing algorithm for a fifteen-minute period over the course of the hour-long trial …

Simulating Mobile Ad Hoc Networks: A Quantitative Evaluation Of Common Manet Simulation Models, Calvin Newport

Dartmouth College Undergraduate Theses

Because it is difficult and costly to conduct real-world mobile ad hoc network experiments, researchers commonly rely on computer simulation to evaluate their routing protocols. However, simulation is far from perfect. A growing number of studies indicate that simulated results can be dramatically affected by several sensitive simulation parameters. It is also commonly noted that most simulation models make simplifying assumptions about radio behavior. This situation casts doubt on the reliability and applicability of many ad hoc network simulation results. In this study, we begin with a large outdoor routing experiment testing the performance of four popular ad hoc algorithms …

Ppl: A Packet Processing Language, Eric G. Krupski

Dartmouth College Undergraduate Theses

Any computing device or system that uses the internet needs to analyze and identify the contents of network packets. Code that does this is often written in C, but reading, identifying, and manipulating network packets in C requires writing tricky and tedious code. Previous work has offered specification languages for describing the format of network packets, which would allow packet type identification without the hassles of doing this task in C. For example, McCann and Chandra's Packet Types [3] system allows the programmer to define arbitrary packet types and generates C unctions which match given data against a specified packet …

Solving Large Mdps Quickly With Partitioned Value Iteration, David Wingate

Theses and Dissertations

Value iteration is not typically considered a viable algorithm for solving large-scale MDPs because it converges too slowly. However, its performance can be dramatically improved by eliminating redundant or useless backups, and by backing up states in the right order. We present several methods designed to help structure value dependency, and present a systematic study of companion prioritization techniques which focus computation in useful regions of the state space. In order to scale to solve ever larger problems, we evaluate all enhancements and methods in the context of parallelizability. Using the enhancements, we discover that in many instances the limiting …

Mobile Agents Simulation With Dassf, Nikita E. Dubrovsky

Dartmouth College Undergraduate Theses

Mobile agents are programs that can migrate from machine to machine in a network of computers and have complete control over their movement. Since the performance space of mobile agents has not been characterized fully, assessing the effectiveness of using mobile agents over a traditional client/server approach currently requires implementing an agent system and running time-consuming experiments. This report presents a simple mobile-agent simulation that can provide quick information on the performance and scalability of a generic information retrieval (IR) mobile-agent system under different network configurations. The simulation is built using the DaSSF and DaSSFNet frameworks, resulting in high performance …

Spatial Multipath Location Aided Routing, Soumendra Nanda

Dartmouth College Master’s Theses

Mobile ad-hoc networks (MANETs) are infrastructure-free networks of mobile nodes that communicate with each other wirelessly. There are several routing schemes that have been proposed and several of these have been already extensively simulated or implemented as well. The primary applications of such networks have been in disaster relief operations, military use, conferencing and environment sensing. There are several ad hoc routing algorithms at present that utilize position information (usually in two dimensional terms) to make routing decisions at each node. Our goal is to utilize three-dimensional (3D) position information to provide more reliable as well as efficient routing for …

Scheduling Pipelined, Multi-Threaded Programs In Linux, Brunn W. Roysden

Dartmouth College Undergraduate Theses

A process causes latency when it performs I/O or communication. Pipelined processes mitigate latency by concurrently executing multiple threads--- sequences of operations--- and overlapping computation, communication, and I/O. When more than one thread is ready to run, the scheduler determines which thread in fact runs. This paper presents techniques for scheduling pipelines, with the following three findings. First, using Linux kernel version 2.6 and the NPTL threads package, we observe a 3-6% performance improvement over kernel version 2.4 and the LinuxThreads package. Second, we test techniques that both take advantage of prior knowledge about whether a program is I/O-bound or …

Efficient Wait-Free Implementation Of Atomic Multi-Word Buffer, Rachel B. Ringel

Dartmouth College Undergraduate Theses

This thesis proposes algorithms for implementing a atomic multi-word buffer, which can be accessed concurrently by multiple readers and a single writer, from the hardware-supported shared memory. The algorithms are required to be wait-free: each process reads or writes the multi-word buffer in a bounded number of its own steps, regardless of whether other processes are fast, slow or have crashed. Our first algorithm is built from multi-writer, multi-reader variables whereas the second algorithm is built from single-writer, multi-reader variables. For either algorithm, the worst-case running time of a read or a write operation on the m-word buffer is O(m). …

Testing The Greenpass Wireless Security System, Kimberly S. Powell

Dartmouth College Undergraduate Theses

Greenpass, developed by Nick Goffee, Sung Hoon Kim, Meiyuan Zhao and John Marchesini under the supervision of Sean Smith and Punch Taylor, is a wireless security solution that implements SPKI/SDSI delegation on top of X.509 keypairs within the EAP-TLS authentication protocol. This system aims to model the decentralized way that authorization flows in real-world enterprise settings and provide a seamless solution that allows for easy access to all resources in the network by both registered users and authorized guests. These goals are achieved through the deployment of a delegation tool, which allows an active entity associated to the organization's network …

Greenpass Client Tools For Delegated Authorization In Wireless Networks, Nicholas C. Goffee

Dartmouth College Master’s Theses

Dartmouth's Greenpass project seeks to provide strong access control to a wireless network while simultaneously providing flexible guest access; to do so, it augments the Wi-Fi Alliance's existing WPA standard, which offers sufficiently strong user authentication and access control, with authorization based on SPKI certificates. SPKI allows certain local users to delegate network access to guests by issuing certificates that state, in essence, "he should get access because I said it's okay." The Greenpass RADIUS server described in Kim's thesis [55] performs an authorization check based on such statements so that guests can obtain network access without requiring a busy …