Seminars and Colloquia

Tuesday, December 01, 2009

04:15 pm - 05:30 pm

Basics of IP Routing: Distance-vector vs. link-state approaches

Speaker: Richard Silverman BA '89, MA '94, D.E. Shaw & Co, L.P.Abstract: When you launch a packet of data onto the Internet, how does it get where it's going? At each hop along the path to its destination, a network device called a router forwards the packet along--but how does each router know the best way to send a given packet to any of several billion possible addresses? Does each router have a complete map of the Internet? If not, how can it make these decisions? And, what happens if the network changes: if a path stops working, or a new one becomes available? To deal with these issues, we have dynamic routing protocols: mechanisms which allow routers to discover each other, and maintain optimal paths to all reachable destinations, deal with link failures and additions, and more. In this talk, we will focus on the class of interior gateway protocols, and discuss the two dominant approaches to routing algorithms, as embodied in the RIP and OSPF routing protocols.Since earning his B.A. in computer science and M.A. in pure mathematics, both at Wesleyan University, Richard Silverman has worked in the fields of networking, formal methods in software development, computer security, and Unix systems administration. He has co-authored two books on computer security published by O'Reilly: SSH, The Secure Shell (The Definitive Guide), and the Linux Security Cookbook. He is currently on the engineering staff of D. E. Shaw & Co., L.P., a company focused on areas it believes can be fundamental technology -- in fields ranging from finance to molecular biology.

ESC 638

Wednesday, December 02, 2009

04:30 pm - 06:00 pm

Robust Signatures for Kernel Data Structures

Speaker: Brendan Dolan-Gavitt '06, Georgia Institute of TechnologyAbstract: Kernel-mode rootkits hide objects such as processes and threads using a technique known as Direct Kernel Object Manipulation (DKOM). Many forensic analysis tools attempt to detect these hidden objects by scanning kernel memory with handmade signatures; however, such signatures are brittle and rely on non-essential features of these data structures, making them easy to evade. In this talk, we examine the security of current signatures and develop principled methods to automatically generate signatures that resist evasion. Our techniques significantly increase the difficulty of hiding objects from signature scanning.

ESC 618

Thursday, February 11, 2010

07:00 pm

Computer Science Applied: A Brief Google Sampler

CONNECTICUT-TRINITY-WESLEYANDISTINGUISHED LECTURE SERIESSpeaker: Christina Schulman, GoogleAbstract: Crawling the web, social networking, personalized recommendations, speech recognition - Google has many interesting projects and products beyond core search and advertising. But how do these areas connect to the topics in your computer science courses? With examples from products like Google News, GOOG-411, and Google Maps, we will discuss some of the computer science concepts that apply to organizing the world's information and making it universally accessible and useful.

Blaustein 210, Connecticut College

Wednesday, April 07, 2010

07:00 pm - 09:00 pm

Tor: Anonymous Communication for Everybody

Speaker: Nick Mathewson, The Tor ProjectAbstract:This talk will present technical and social issues surrounding Tor (https://wwww.torproject.org), a free-software onion routing network that helps people around the world use the Internet in privacy.The public Tor network has over 1000 volunteer-operated servers on six continents. Our hundreds of thousands of users include ordinary citizens who want protection from identity theft and prying corporations, corporations who want to look at a competitor's website in private, soldiers and aid workers abroad who need to contact their home servers without fear of physical harm, and people in censored areas who want to use the Internet without the authorities deciding what they're allowed to see.This talk will provide an introduction to the basic working designs that make anonymity networks like ours work, and discuss the technical choices that brought us here. We'll also discuss some social and policy implications with a focus on the importance of anonymous communications layers to a wide variety of constituencies, and on the interactions between anonymity networks and policy-based privacy solutions and security initiatives.

ESC 184 (Woodhead Lounge)

Thursday, September 16, 2010

04:15 pm - 05:30 pm

Software Engineering Using RATionale

Speaker: Janet Burge, Miami University, OhioAbstract: Abstract: Many decisions have to be made when developing a software system and a successful outcome depends on how well thought out these decisions were. The decisions made, and alternatives considered, form the rationale for the system. The rationale goes beyond standard documentation by describing the developers intent and all alternatives considered rather than only those selected. While the potential usefulness of this information is seldom questioned, the rationale is rarely captured in practice. There is a pervasive belief that developers will not be willing to take the time and effort to perform what might be perceived as extra documentation. In order to encourage rationale capture there needs to be some incentive to do so.This talk describes the Software Engineering Using RATionale system (SEURAT). SEURAT is integrated with the Eclipse Interactive Development Environment and inferences over the rationale to evaluate decision alternatives and perform impact assessment when requirements, development criteria, and assumptions change. In addition to development environment integration, SEURAT also supports importing rationale extracted from external sources, such as Word documents, to help further reduce the effort of rationale capture. SEURAT also interfaces with the XFeature feature modeling tool so that rationale can be used to help customers use the rationale to guide product feature selection.Biography: Janet Burge is an Assistant Professor in the Miami University Computer Science and Software Engineering department. She received her Ph.D. in Computer Science from Worcester Polytechnic Institute (2005) and performed her undergraduate work at Michigan Technological University (1984). Her research interests include design rationale, software engineering, AI in design, and knowledge elicitation. She is a co-author (with Jack Carroll, Ray McCall,and Ivan Mistrik) of the book Rationale-Based Software Engineering. Dr. Burge is a recipient of a NSF CAREER Award for her project Rationale Capture for High-Assurance Systems. She has been at Miami University since 2005. Prior to that point, she worked for more than 20 years in industry as a software engineer and research scientist.

ESC 638

Tuesday, September 28, 2010

04:15 pm - 05:30 pm

Detecting and Defending Against Attacks on Tor

Speaker: Sam DeFabbia-KaneAbstract: Tor is a low-latency anonymity network used worldwide by governments, dissidents, journalists, and other people who can benefit from anonymity online. Tor works by forwarding its users connections through a series of volunteer-run Tor routers, so that a single centralized authority cannot compromise Tors anonymity.However, this design does leave Tor open to several kinds of attacks by people running or observing Tor routers. This talk focuses on one of those attacks: an end-to-end correlation attack whereby an attacker can identify a user by comparing timing data taken from data streams at the beginning and end of the Tor circuit. The talk will cover some variations on the attack and our efforts at detecting attackers implementing one variation in particular: a denial of service attack proposed by Borisov et al., as well as our future plans for investigating the effectiveness of end-to-end correlation on the Tor network itself.

ESC 339

Monday, October 11, 2010

12:00 pm - 01:00 pm

Dynamical Intelligence: Navigation and Intention

Speaker: Eric Aaron, Wesleyan UniversityAbstract: Intelligent computational \emph{embodied agents}, whether virtual (characters in animated worlds) or physical (mobile robots), move through their worlds, performing sequences of tasks to achieve their goals. To succeed in complicated or unpredictable environments without human intervention, these agents must be autonomously responsive and adaptive in their worlds--for instance, they need to avoid collisions with obstacles as they move, and they may need to adjust the sequences of tasks they intend to perform to reflect new priorities. In this talk, I present dynamically responsive approaches to collision-free navigation and intention-guided task sequencing for embodied agents, and I describe \emph{hybrid dynamical cognitive agents} (HDCAs), which smoothly integrate these navigation and task-sequencing levels of intelligence. By enhancing low-level, dynamically sensitive intelligence without minimizing high-level, logic-based intelligence, the underlying HDCA framework can extend some capabilities of embodied agents, and it may have implications for related learning-based, developmental, and dynamicist approaches to behavior modeling.

ESC 339

Friday, October 29, 2010

12:00 pm - 01:15 pm

Algorithmic Detection of Computer Generated Text and Measures of Paper Citations

Speaker: M.S. Krishnamoorthy, RPIAbstract: The talk consists of two parts. The first part discusses Detection of Computer Generated Text.Computer generated academic papers have been used to expose a lack of thorough human review at several computer science conferences.We assess the problem of classifying such documents. After identifying and evaluating several quantifiable features of academic papers, we apply methods from machine learning to build a binary classifier.In tests with two hundred papers, the resulting classifier correctly labeled papers either as human written or as computer generated with no false classifications of computer generated papers as human and a 2% false classification rate for human papers as computer generated.The second part discusses the measures of citations of Scientific Papaers.A new way of computing the value of citations is introduced and compared with the PageRank algorithms for author ranking. In our proposed approach, the value of each paper is expressed in CENTs (scientific currency tokens).The paper.s value is then divided by the number of citations of that paper yielding the value for each citation. As citations are the acknowledgment of the value of the work of authors other than oneself (such citation is equivalent to full acknowledgment of a publication that has been useful), then self citations count as zero acknowledgment. Circular citations, as a generalized type of self citations, will be considered at reduced acknowledgment value smaller than a full one. Finally, we propose a redefinition of the h-index, as the largest integer such that the h-th paper (on the list of papers sorted by their CENTs values) is worth more than the h CENTs. The new index, termed i-index or i2 in short, appears to be a more precise measure of the impact of authors. papers and their productivity than the h-index.

ESC 339

Tuesday, November 16, 2010

04:15 pm - 05:30 pm

Comparison of Ecotype Demarcation Algorithms

Speaker: Carlos Francisco, Wesleyan '11Abstract: For a long time, microbiology has concerned itself with its own version of the 'species problem' - that there are multiple proposed definitions of what exactly species are and that biologists have yet to agree upon which definition calls for the most sensible criteria. For microbiologists, the problem is exacerbated by bacteria existing in very large populations and accumulating mutations at a much higher rate, allowing them to diverge much more quickly. A named species of bacteria might be extremely diverse genotypically and phenotypically, one example being /Escherichia coli. /Within a named species, there might be multiple clusters of bacteria that are adapted to a particular ecological niche. We call these groups 'ecotypes.' It would be of great benefit to be able to demarcate the ecotypes in a set of bacteria, and with the advent of gene and full genome sequencing, we are now able to do this algorithmically.In this talk, I will present four distinct algorithms that tackle the problem of figuring out which bacterial strains are in which ecotypes. To compare their qualities, we first used an algorithm that generates simulated nucleotide strains and the 'correct' ecotypes for those strains. We then ran each ecotype demarcation algorithm on those strains and compare them to the 'real' ecotypes using a metric called variation of information. I will talk about the algorithms involved and how they work, the accuracy of the results each algorithm produced, the running times of the algorithms, and I will also provide an example of how each algorithm runs on a set of real, sequenced bacterial data.

ESC 339

Tuesday, February 15, 2011

04:15 pm - 05:30 pm

Combinatorics of RNA Secondary Structures and Related Problems

Speaker: Danny Krizanc, WesleyanAbstract: We derive expressions for the asymptotic number of RNA secondary structures satisfying a variety of constraints. We also discuss the asymptotics of the expected number of base pairs in randomly chosen structures, again, under different constraints.Finally, we relate these results to problems arising in the analysis of algorithms.

ESC 339

Thursday, February 24, 2011

12:00 pm - 01:00 pm

A review and update on Tor

Speaker: Andrew Lewman, The Tor ProjectAbstract: A review and update on Tor, how open source solutions work well worldwide, where we're headed, and where we need help from developers like you.Why Tor?Tor is a tool to protect your online privacy and anonymity. We rely on thousands of volunteers to run our network, review our code, and help enhance the experience for all.Lunch will be served.

ESC 184 (Woodhead Lounge)

Tuesday, March 22, 2011

04:15 pm - 05:30 pm

It's Not "Junk": Using Genetic Algorithms to Search for Functional Regions in Noncoding DNA

Speaker: Clare Bates Congdon, '85, University of Southern MaineAbstract: Over 95 percent of our DNA does not directly code for genes. Formerly called "junk" DNA, it is now understood that some of these noncoding regions are functional... but determining which regions are functional is a complex problem. Our hypothesis is that regions of noncoding DNA that have been conserved across evolutionary time are good candidates as functional elements. As computer scientists, our role is to identify patterns (aka motifs) that appear to be conserved through evolution. To find these motifs, we use a search approach called genetic algorithms, in which one "evolves" the solution to a problem.In this talk, I'll describe GAMI, a genetic algorithms approach to motif inference. The talk will describe the motif inference problem, the genetic algorithms approach in general, and the specific GAMI system design, as well as some of the datasets that we have studied using this approach, and our recent results.

ESC 339

Tuesday, March 29, 2011

04:15 pm - 05:30 pm

TBA

Speaker: Marc Liberatore, UMass AmherstAbstract: TBA

ESC 339

Thursday, April 07, 2011

04:15 pm - 05:15 pm

Decisions, Decisions

Speaker: Eli Fox-Epstein, '10Abstract: In this talk, I'll describe the forbidden pairs problem. When there are constraints on which vertices or edges one can employ, finding a subgraph with a property can become much more difficult. We generalize a proof technique to describe the complexity of infinitely many problems, instead of individual problems.

ESC 339

Tuesday, April 19, 2011

04:15 pm - 05:30 pm

Challenges in Internet Investigations

Speaker: Marc Liberatore, UMass AmherstAbstract: Law enforcement, computer security professionals and other investigators work to discover, document, and potentially prosecute crimes facilitated by the Internet. This work ranges widely, encompassing tasks such as observing new malware, documenting network intrusions, or trafficking in digital contraband. Recently, my colleagues and I have developed a suite of tools to ease investigation by law enforcement of contraband trafficking on peer-to-peer filesharing networks. These tools generate a plethora of leads for investigators, and it is now clear that determining the dangerousness of suspects is of key importance. This problem, of modeling suspects' behavior on the basis of many observations over time, is an example of a question of computational social science. In this talk, I will describe the basis of our tools and measurements, touching upon the legal and practical aspects of these investigations. I will also present results of our measurements over the last 15 months, and discuss the challenges ahead.

ESC 339

Wednesday, April 20, 2011

04:15 pm - 05:30 pm

Simulating circuit creation in Tor

Speaker: William Boyd, Wesleyan, Senior Thesis PresentationAbstract: All computer security systems are subject to attacks. When attacks are proposed, they must be tested to determine practicability in real-world usage (and thus whether defenses are needed or possible). It is not always possible, practical or ethical to test attacks on the real systems they target; thus, attacks are often tested in simulation. We have found in our research on the anonymity network Tor that many simulations make unreasonable or unjustified assumptions; we thus attempt to produce an accurate, justified simulation on which to easily test attacks.I'll be describing and justifying the methods we use to simulate circuit creation, a particular attackable aspect of the behavior Tor. We directly observe the behavior of the extant network, and attempt to construct a set of hidden Markov models which accurately simulate this behavior. Particular challenges we've faced include determining a suitable description of network behavior, simplifying our observations to make HMM generation computationally feasible, and objectively evaluating the accuracy of our simulation.

ESC 339

Monday, April 25, 2011

04:15 pm - 06:00 pm

Dynamical BDI-Based Intention Recognition for Virtual Agents

Speaker: Ted Nichols, '10, M.A. Thesis DefenseAbstract: Virtual agents might need to recognize the intentions of other agents in order to adapt to a dynamic environment. In this talk, I will discuss ways to incorporate intention recognition into the cognitive system of a hybrid dynamical cognitive agent (HDCA). HDCAs have cognitive systems that consist of beliefs, desires, and intentions that evolve dynamically over time. While intention recognition methods for Belief-Desire-Intention (BDI) architectures have been implemented in the literature, none have been based on dynamical BDI systems. Our work was motivated by the intention recognition tasks that might face an informal college tour guide; adding intention recognition beliefs to a guide's cognitive system allows the guide to respond dynamically to the intentions of a tour taker.

ESC 339

Tuesday, April 26, 2011

04:15 pm - 05:30 pm

A dynamical systems-based model for indoor robot navigation

Speaker: Juan Pablo Mendoza, Wesleyan, M.A. Thesis DefenseAbstract: Common indoor environments are particularly challenging scenarios forautonomous robot navigation: robots may need to navigate in relativelytight and complicated paths while being responsive to unpredictablechanges in the environment, such as those created by humans walkingaround. In my talk, I will describe a new, dynamical systems-basedmodel for autonomous indoor navigation. In the dynamical systemsapproach to behavior modeling, safe navigation around obstacles andtoward a goal is achieved by letting carefully designed differentialequations control the evolution in time of the robot's headingdirection as it navigates through its environment. Unlike previousdynamical systems-based navigation models, this one focuses onaddressing the problems of navigation in indoor environments.Simulations and real robot results support the effectiveness of thenavigation model presented.Only very basic knowledge of differential equations will be assumed.

ESC 339