Abstracts of the ISI AI Seminar Series in 2002
1995 Schedule 1996 Schedule 1997 Schedule 1998 Schedule 1999 Schedule 2000 Schedule 2001 Schedule 2002 Schedule
Sattiraju Prabhakar - January 18, 2002
Yigal Arens - January 25, 2002
Charles Elkan - February 1, 2002
William Swartout - February 15, 2002
Elaine Chew - March 8, 2002
Udo Hahn - March 29, 2002
Cyrus Shahabi - April 5, 2002
Tim Chen - April 12, 2002
Marie desJardins - April 26, 2002
Andrew S. Gordon - May 31, 2002
Dario Nardi - June 14, 2002
Corey Anderson - June 18, 2002
Douglas W. Oard - August 2, 2002
Raymond Mooney - September 13, 2002
Toru Ishida - September 23, 2002
Aram Galstyan - September 27, 2002
Tad Hogg - October 4, 2002
Kevin Knight - November 1, 2002
Ion Muslea - November 15, 2002
Friday, January 18, 2002
Autonomous Learning of Object Models from Visual Data
Sattiraju Prabhakar
USC's Information Sciences Institute
Autonomous Agents are often required to perform complex tasks in new environments. They may need to navigate in a new environment, or reconfigure the objects in the environment. The 3D shapes are an important aspect of objects, which can play a vital role in tasks such as navigation, behavioral interaction between different objects, etc. In this talk, I will present an algorithm that transforms the visual percepts from static objects and actions into a decision supportive graph. Using this graph, the agent will be able to predict the consequences of its actions, or plan a sequence of actions. The input percept to the agent is a group of features in their parametric form. The features are generic points, edges and surfaces. The agent transforms these shape parametric features into action parametric features in each model state. Using these the agent selects actions. The model building for an environment is structured - one object at a time; and for each object it is layered. I will relate this approach to inductive learning and reinforcement learning. I will present some of our recent results for model building and navigation.
Friday, January 25, 2002
The state of the division address
Yigal Arens
USC's Information Sciences Institute
People have their own perceptions regarding ISD: How we compare to other research places, in what fields the majority of research is done, how much we publish. I've recently discovered that those perceptions -- including my own -- are often wrong.
Do you want to hear how well we're *really* doing here? Do you want to find out about the changes we'll be facing in the near future? Come to this talk and find out!
Friday, February 1, 2002
Shared Challenges in Data Mining and Computational Biology
Charles Elkan
http://www-cse.ucsd.edu/users/elkan/
University of San Diego
In this talk I shall discuss several fundamental research issues that must be addressed to enable continued progress both in computational biology and in data mining. The issues include:
Speaker bio:
Charles Elkan is an associate professor in the Department
of Computer Science and Engineering at the University of California, San
Diego. His main research interests are in artificial intelligence and data
mining. His research has led to two best paper awards and first place in
two international data mining contests. In 1998/99 Dr. Elkan was a
visiting associate professor at Harvard. He earned his Ph.D. at Cornell
University in computer science, and his B.A. at Cambridge University in
mathematics.
February 15, 2002
Bringing Together Simulation Research and the Entertainment Industry
William R. Swartout
USC Institute for Creative Technologies
On August 18th, 1999, the USC Institute for Creative Technologies was established with funding from the US Army. The ICT seeks to enlist the talents of the entertainment industry, which brings expertise in story, character, visual effects and production; game developers, who bring interactive game play and modeling resources; and the computer science community, which brings innovation in graphics, artificial intelligence, simulation and virtual reality technology. By bringing together these various communities that have not interacted much in the past, the hope is that synergies will emerge that will enable the creation of much more compelling simulations.
In the brief period since its opening the ICT has already started to deliver on this promise. In this talk I will describe some of the insights that have emerged from this collaboration, the major research efforts we have undertaken in areas such as graphics, artificial intelligence and sound, and the integrating virtual reality applications we have produced in areas such as mission rehearsal and leadership training.
March 8, 2002
Exploiting the Structure of Musical Information Processing
Elaine Chew
Department of Industrial and Systems Engineering
Integrated Media Systems Center
University of Southern California
The music with which we are most familiar is tonal in nature and possesses well-studied hierarchical properties. We introduce the Spiral Array, a 3-D representation of musical artefacts that is optimized for recognizing tonal structure. Applications include cognitive modeling, automated analysis, audio synchronization and music information visualization, comparison and categorization.
The Spiral Array utilizes both discrete and continuous space, and represents musical entities from different hierarchical levels in the same space for easy comparison. Euclidean metrics are used to capture salient perceptual cues in order to quantify tonal properties. By incrementally aggregating musical time series data, the information map to meaningful spatial trajectories. A key-finding application will be discussed.
BIOSKETCH
Dr. Elaine Chew joined the faculty at USC this past fall as an
Assistant Professor in the Department of Industrial and Systems
Engineering and a Senior Investigator at the Integrated Media Systems
Center. Dr. Chew received her S.M. and Ph.D. in Operations Research
from MIT, and a B.A.S. in Music and Computational Mathematics from
Stanford University. Her primary research interests lie in the
design of computational models and algorithms for problems in music
perception and cognition.
Dr. Chew also enjoys creating innovative concert programs combining non-traditional and classical styles. She will be collaborating with Chris Kyriakakis and Dennis Thurmond in an upcoming performance art project titled "Flying Sonics! A Tale of Immersive Audio and Diverse Instruments" at USC?s Newman Hall on April 15th.
Friday, March 29, 2002
Biomedical Ontology Engineering -
Challenges of Large-Scale Natural Language Processing
Udo Hahn
CLIF Text Knowledge Engineering Lab
Albert-Ludwigs-Universität Freiburg
The talk starts from the premise that any deeper understanding of biomedical documents (technical or physicians' reports, journal articles, etc.) poses strong requirements on the kinds of domain-specific background knowledge to be supplied. From an ontological point of view, knowledge types which are particularly relevant include taxonomic, partonomic and topological knowledge. A report on a large-scale experiment is given how these rich forms of knowledge can be extracted automatically from a semantically weak, though high-coverage biomedical knowledge repository, the UMLS thesaurus.
Udo Hahn is currently an associate professor for natural language processing at the University of Freiburg, Germany. He holds a doctoral degree in information science from Constance University. His interests include a wide range of applications of automatic text analysis, such as information extraction, text summarization and text mining.
Friday, April 12, 2002
Some Computational Problems in Biology
Tim Chen
University of Southern California
Biological Sciences
Understanding functions of genes and their RNA and protein products in cells is the major goal in molecular biology. The Human Genome Project has not only accomplished the sequencing of the entire human genome but also provided the genome sequences of many model organisms and their related species. In the post-genomic era, many high-throughput technologies, such as DNA microarrays, tandem mass spectrometry, Yeast two-hybrid assays, protein arrays and phenotypic arrays, have been developed to tackle the functions of genes from various directions and levels. Huge amount of biological data have been generated by these techniques. In this talk, we introduce the computational challenges arisen from these development such as designing and managing biological databases, collecting and processing raw instrumental data into biological data, modeling biological processes, interpreting data into biological functions, and intergrating biological information to infer biological functions.
Bio:
Dr. Chen is an assistant professor of Biology, Computer Science, and
Mathematics at the University of Southern California. He was a Lecturer
and Research Fellow at George M. Church Laboratory and the Lipper Center
for Computational Genetics, Harvard Medical School from 1997 to 2000.
He received his Ph.D. degree (1997) in Computer Science from the State
University of New York at Stony Brook and B.E. degree (1993) in
Computer Science and Engineering from Tsinghua University , Beijing.
Dr. Chen's research focuses on the applications of computer science and
mathematics in biology and medicine.
Friday, April 5, 2002
Mining Multidimensional Databases
Cyrus Shahabi
University of Southern California
I will start by reviewing some examples of multidimensional data sets and their corresponding applications. Subsequently, I will focus on one of our research projects and provide some in-depth explanations. I will present our technique for evaluating range aggregate queries (e.g., summation, count and variance) on multidimensional data sets, termed Progressive Polynomial Analytical Processing (PROPOLYNE).
Many data mining and analysis applications rely on evaluation of range aggregate functions. While aggregations such as COUNT and SUM are important, improving support for range multivariate statistics can significantly extend the reach of existing technology and open the door to new methods. We show that these and many other queries can be derived from polynomial range-sum queries, and propose a novel pre-aggregation method called PROPOLYNE to support progressive evaluation of arbitrary polynomial range-sums. PROPOLYNE is wavelet-based, but uses query approximation rather than data compression. PROPOLYNE is an excellent exact algorithm because well-chosen wavelets approximate range aggregate queries extremely well. At its foundation, PROPOLYNE is a data independent progressive query evaluation algorithm. At each step it makes the best possible wavelet approximation of the submitted query, and retrieves only the data needed to evaluate this approximation. Our experiments demonstrate that the approximate results produced by PROPOLYNE for several empirical datasets are very accurate after a small number of I/O's and the error becomes negligible long before the exact computation is complete. We also show that the accuracy of results produced by typical wavelet-based data compression techniques vary wildly with the dataset, and at its best is always significantly worse than that of PROPOLYNE.
Bio:
Cyrus Shahabi is currently an Assistant Professor and the Director of
the Information Laboratory at the Computer Science Department of the
University of Southern California (USC). He is also the Director of
the Information Management Research Area at the Integrated Media
Systems Center (IMSC), an NSF Engineering Research Center at USC. He
received his M.S. and Ph.D. degrees in Computer Science from the
University of Southern California in August 1993 and 1996,
respectively. His B.S. degree is in Computer Engineering from Sharif
University of Technology at Tehran. He has more than sixty articles,
book chapters, and conference papers in the areas of databases and
multimedia. Dr. Shahabi's current research interests include
Multidimensional Databases, Multimedia Servers, and Data Mining.
Friday, April 26, 2002
Communication-Sensitive Decision Making in Multi-Agent Systems
Marie desJardins
University of Maryland
(Joint work with Michael Wolverton and Karen Myers, SRI International)
In this talk, I will present ongoing work on developing techniques for
intelligent agent control and coordination in a dynamic, real-time,
multi-agent setting. The application domain, consisting of teams of
autonomous air vehicles (AAVs), is characterized by dynamic
environments, real-time response requirements, limited information,
and unreliable, low-bandwidth communications.
We have developed an initial framework in which agents' decision making is sensitive to communication availability and costs, tradeoffs among multiple objectives, and reliability of information about other agents (friendly and hostile) in the environment. This talk will focus on reasoning about communication constraints to inform action selection during planning and execution. We have developed a simulated experimental testbed for exploring different communication models and planning techniques. I will describe the application domain and testbed, and will present initial experimental results.
Speaker Information:
Dr. Marie desJardins is an assistant professor in the Department
of Computer Science and Engineering at the University of Maryland,
Baltimore County. Prior to joining the faculty in 2001, she was
a senior computer scientist in the AI Center at SRI International in
Menlo Park, California. Her research is in artificial intelligence,
focusing on the areas of machine learning, planning, multi-agent
systems, information management, reasoning with uncertainty, and
decision theory.
Dr. desJardins can be contacted at the Dept. of CS&EE, UMBC, 1000 Hilltop Circle, Baltimore MD 21250, mariedj@cs.umbc.edu, (410) 455-3967.
May 31, 2002
Strategy Representation And The Mental Models In Human Planning Knowledge
Andrew S. Gordon
USC Institute for Creative Technologies
People have remarkable abilities in recognizing, comparing, and reasoning about strategies in their daily lives despite their high level of abstraction. Strategies are often seen as the commonalities across analogous planning cases, but are more than simply abstract plans - they describe the reasoning processes of the agents in planning cases. As our best models of human analogical reasoning are premised on the alignment of structured representations, the mental representation of strategies must also include structured representations of the reasoning processes of people. This talk will describe a large-scale knowledge representation effort that was done in order to investigate the conceptual requirements of strategies and their underlying mental models. 372 strategies were collected and analyzed from 10 domains of human planning (business, object counting, education, government, artistic performance, personal relationships, science, warfare, and the anthropomorphic domains of animal behavior and immunology). The analysis of these strategies reveals that their component concepts (nearly one thousand terms) include large portions that have previously received little attention within the formal knowledge representation community. Many of these terms describe components a mental model of human reasoning (a folk psychology or theory of mind) that parallels much of the computational modeling work that has been done in Artificial Intelligence and Cognitive Psychology. By describing this mental model in some detail, this research offers new opportunities for the design of human-computer interactions and anthropomorphic agent architectures, and furthers the psychological investigation of social and introspective reasoning.
Bio:
Dr. Andrew S. Gordon is a Research Scientist at the University of
Southern California Institute for Creative Technologies. Before
arriving at USC, he held postdoctoral positions in the Psychology
department of the University of California Los Angeles and the IBM
T.J. Watson Research Center in Hawthorne, New York. He received his
Ph.D. in Computer Science and B.A. in Cognitive Science from
Northwestern University.
June 14, 2002
Talking To Truman - Exploring Intelligence As Communication
Dario Nardi
University of California Los Angeles
Truman is a scripting language, a virtual agent, and an experiment in social intelligence. Maybe you are a player character in a virtual world, or maybe you are interacting with a robot or an appliance - just speak into a microphone, let Truman "think", and then hear what the virtual non-player character, robot or appliance has to say about the time your neighbors, its feelings about you, or your apparent personality style. Truman is not Eliza or Alice, nor is it the Cyc Project. It is a natural language system that remembers information, conveys gossip, makes inferences and analogies, engages in group activities, and so on. How does it work? In keeping with a situated-action philosophy, dialog skills and reasoning skills are integrated, while the specifics of a Truman agent's knowledge are widely distributed in a context-sensitive subsumption architecture. The scripting language is a fully featured programming language designed to meet many of the needs of dialog and social reasoning. This use of a scripting language, instead of a formal architecture, allows a virtual agent to be organic and able to meet many of the often-arbitrary needs of natural language. This experiment has focused on handling what to hear, what to say, what to remember, what to reflect on, what to relate to others, and similar socially-relevant functions. Truman can also recall information from one interaction to the next with a user, share information between multiple users, learn new information from a trusted user, reflect on its own programming and progress, and engage in in-situ activities such as giving lectures or eating meals. Naturally, truman does not do everything. It does make mistakes. It's still growing. It isn't as smart as the average person. Rather, Truman is an on-going exploration of what happens when we try to embody a few everyday social processes in a machine.
Bio:
Dario Nardi is currently an assistant adjunct professor in UCLA's
Program in Computing. He completed his Ph.D. in Systems Science in
1998 from SUNY Binghamton's Watson School of Engineering. He is also a
research fellow with the Temperament Research Institute. Dario has
authored and co-authored 4 books in organizational psychology, does
research in artificial intelligence, web-based learning and
undergraduate curriculum design, and runs live social-psychology
simulations. More information can be found at www.darionardi.com.
June 18, 2002
A Machine Learning Approach to Improving Web Navigation
Corey Anderson
University of Washington
Most web sites today are designed one-size-fits-all: all visitors see the exact same pages regardless of interests, previous interactions, or, frequently, even browsing client (desktop PC or wireless PDA). But one size often does not fit all. Instead of presenting the same content, the web experience should be dynamic and personalized, adapting to visitors' preferences as evinced in previous interactions.
In this talk I will give an overview of our Proteus framework for personalizing the web experience. Proteus adapts the presentation of content and navigation between pages, and targets personalizations for individual visitors or groups of similarly behaving visitors. I'll detail one particular adaptation -- adding new navigational shortcuts -- and describe our MinPath algorithm for finding shortcuts efficiently. A challenge for MinPath and modeling web navigation is that training data for an entire site may be plentiful, but sparse for any individual page. This difficulty can be overcome, however, by noting that most large web sites have a rich underlying relational structure that can be exploited for generalization: pages can belong to different types (e.g., pages about laptop computers vs. pages about printers), with each type described by a different set of attributes (e.g., size of display vs. printing speed). We leverage this structure by developing Relational Markov Models (RMMs). States in an RMM belong to relations and are described by variables over hierarchically structured domains. Based on these hierarchies, the RMM defines sets of related states, learns transition probabilities between these sets, and uses shrinkage to estimate transitions between individual pages. I will present RMMs in detail and provide results showing that they outperform traditional Markov models for predicting web navigation by a substantial margin.
Bio:
Corin Anderson is a final-year Ph.D. student at the University of
Washington. His research interests cover artificial intelligence, machine
learning, intelligent user interfaces, data mining, and applications of
these to challenging problems. Outside of research, Corin occupies
himself with running, cycling, photography, and contributing to open
source software.
August 2, 2002
Searching Spoken Word Collections
Douglas W. Oard
University of Maryland
on sabbatical at USC Information Sciences Institute
Spoken word collections promise access to unique and compelling content, and most of the needed technology to realize that promise is now in place. Decreasing storage costs, increasing network capacity, and easy availability of software to exchange digital audio make possible physical access to spoken word collections at a previously unimaginable scale. Effective support for intellectual access -- the problem of finding what you are looking for -- is much more challenging, however. In this talk I will review the work that has been done on this problem at the Text Retrieval Conferences and the Topic Detection and Tracking evaluations, and I will present some early results from a user study comparing present manual and automated approaches to indexing spoken word collections. I will then describe a unique resource, a collection of 116,000 hours of oral history interviews recorded in 32 languages in 67 countries, and explain how we are leveraging an unprecedented manual indexing effort to develop the ability to index similar materials automatically.
Bio:
Doug Oard is an Associate Professor at the University of Maryland,
with a joint appointment in the College of Information Studies and the
Institute for Advanced Computer Studies. He will be on sabbatical in
the Natural Language Group at USC-ISI through August, 2003. He holds
a Ph.D. in Electrical Engineering from the University of Maryland, and
his research interests center around the use of emerging technologies
to support information seeking by end users. Dr. Oard's recent work
has focused on cross-language information retrieval, retrieval from
audio, data mining from text, and the exchange of ratings by networked
users. Additional information is available at
http://www.glue.umd.edu/~oard/.
September 13, 2002
Text Mining with Information Extraction
Raymond Mooney
University of Texas at Austin
Information extraction (IE) is a form of shallow text understanding that locates specific pieces of data in natural language documents. An IE system is therefore capable of transforming a corpus of unstructured texts or web pages into a structured database. Our previous work has focused on using machine learning methods to automatically construct IE systems from training sets of manually annotated documents. Our current research focuses on a form of text mining that extracts a database from a document corpus using a learned IE system and then mines this database for interesting patterns using rule induction. The noise and variation in automatically extracted text requires rule mining methods that allow "soft" matching to the data based on textual similarity. We have developed two methods for inducing "soft matching" rules from textual data, one based on integrating rule induction and nearest-neighbor learning and another based on modifying association rule mining. Results on several extracted datasets will be presented.
Bio:
Raymond J. Mooney is a Professor in the Department of Computer
Sciences at the University of Texas at Austin. He received his
Ph.D. in 1988 from the University of Illinois at Urbana/Champaign. He
is an author of over 80 published papers in artificial intelligence,
primarily in the area of machine learning, and a former editor for the
Machine Learning journal. His recent research has focused on text
mining, learning for natural-language processing, information
extraction, text categorization, recommender systems, relational
learning, inductive logic programming, and semi-supervised
learning. Additional information is available on the World Wide Web
at
http://www.cs.utexas.edu/users/mooney.
September 23, 2002
Social Agents in Digital Cities
Toru Ishida
Kyoto University
The research community tackling agents and multiagent systems has studied and developed various agents. Typically, personal agents belong to humans and help their users to operate complex computer/communication systems. In the area of multiagent systems, though computational agents are designed to interact (both collaborate and compete) with each other, interaction among humans and computational agents has not been studied intensively. In this talk, however, I focus on social agents that can be members of a human community: social agents support human-human interactions, while personal agents support human-computer interactions. To understand the nature of social agents, we need a research platform to play with them. This talk proposes a scenario description language called Q for designing interactions among a large number of agents, and its application to digital cities and crisis management simulations. We started a five years project to develop social agents for supporting social interactions in digital cities.
Bio:
Toru Ishida received the B.E., M.Eng. and D.Eng. from Kyoto
University, Kyoto, Japan, in 1976, 1978 and 1989, respectively. He is
an IEEE fellow from Jan. 2002. He is currently a professor of
Department of Social Informatics, Kyoto University, Kyoto, Japan. From
1978 to 1993, he was a research scientist of NTT Laboratories. He has
been working on parallel, distributed and multiagent production
systems from 1983. He proposed parallel rule firing, and extended it
to distributed rule firing. Organizational self-design was then
introduced into distributed production systems for increasing
adaptiveness. From 1990, he started working on realtime search for learning
autonomous agents. Again, organizational adaptation becomes a central issue
in controlling multiple problem solving agents. He started working on
community computing in 1995. He is leading digital cities and intercultural
collaboration projects in Kyoto.
September 27, 2002
Congestion Games and Emergent Coordination in Non-Stationary Environments
Aram Galstyan
USC's Information Sciences Institute
In recent years there has been growing interest in using game-dynamical mechanisms for controlling large-scale multi-agent systems (MAS). Such systems may possess certain global properties that can not be simply deduced from details of the microscopic characteristics of individual agents, but arise out of interactions among many agents. In particular, it has been established that in a system of competetive agents with bounded rationality, simple interaction rules can lead to a globally optimal (or near-optimal) system performance, a phenomenon commonly termed as Emergent Coordination.
In this talk I will present a model of game-dynamical MAS that demonstrates emergent coordination and is, moreover, very robust and adaptive to changes in the environment. Our model consists of locally interacting boolean agents that compete for a limited resource. The capacity of the resource is allowed to vary externally, mimicking a dynamic environment. At each time step the agents face a binary choice of whether to use the resource or not, and those who use the resource are rewarded (punished) if their number is less (greater) than resource capacity. The framework of the inter-agent interactions is based on random boolean networks (Kauffman's NK model), where each agent (node) gets its input from K other randomly chosen agents, and maps the input to a new state according to a boolean function of K variables. The generalization we make is that the agents are allowed to adapt by having more than one boolean function, or strategy, and the use of a particular strategy is determined according to a simple reinforcement learning scheme. Our results indicate that for some parameters of the network the system shows a tendency towards self organization into a phase characterized by very effective utilization of the resource, even for relatively large variations in the capacity level. Remarkably, this parameter range corresponds to the boundary of ordered/chaotic phases in the prototype boolean networks. I will also talk about a generalization of our model for a multiple-resource case, and consider other potential applications of adaptive boolean networks, such as solving kSAT problems.
Bio:
Aram Galstyan is a research associate at the USC's Information
Sciences Institute. He received his Ph.D. in theoretical physics
from the University of Utah, in 2000. His current research is
focused on the use of statistical physics and numerical methods
for analyzing emergent phenomenon in large scale multi-agent
systems.
October 4, 2002
Exploiting Problem Structure with Quantum Computers
Tad Hogg
HP Labs
Combinatorial searches, such as arise, for example, in scheduling, gene sequencing, cryptography and discrete statistical physics models, are difficult to solve because the computation time grows exponentially with the size of the problem. Quantum computers, by evaluating all possible combinations simultaneously, offer the possibility of much faster searches.
Beyond the challenge of building quantum computers, realizing this possibility requires matching the quantum algorithm to the combinatorial properties of particular problems. Since these are not known in advance, it appears unlikely quantum computers can rapidly solve all combinatorial searches.
Fortunately, random ensembles of search problems have robust regularities related to phase transitions in search behavior. This talk will describe how these regularities apply to give heuristic search algorithms for quantum computers, i.e., algorithms that work well for many, but not all, searches. The heuristics use a sequence of small changes to the amplitudes associated with the quantum computer, so can be viewed as a discrete version of the recently introduced technique of adiabatic quantum computing. The heuristics also help match algorithms to limited hardware capabilities, e.g., by reducing required coherence times.
I will also present open questions on the design and behavior of these algorithms. In particular, a mean-field analysis suggests heuristics can be quite effective, on average, for commonly studied NP-hard combinatorial searches such as satisfiability, graph coloring and traveling salesman. Thus a significant open question is whether more accurate statistical methods can verify this conclusion or identify even better heuristics.
For further background, see T. Hogg, Quantum Search Heuristics, Physical Review A, 61:052311, 2000 (http://publish.aps.org/abstract/pra/v61/e052311) or, for a nontechnical overview, the 2nd essay in http://www.computer.org/intelligent/ex1999/pdf/x4009.pdf
Bio:
Please visit: http://www.hpl.hp.com/shl/people/tad
November 1, 2002
What's New in Statistical Machine Translation
Kevin Knight
USC-ISI
A lot of knowledge of how to do language translation is implicit in people's heads. It is tough to extract that knowledge and to encode it in algorithmic form. On the other hand, there is also a lot of translation knowledge implicit in large quantities of human-translated material (available, for example, from the United Nations). I will talk about some recent work aimed at extracting this knowledge through automatic machine learning techniques.
Bio:
Kevin Knight is a Project Leader at the USC/Information Sciences Institute. He is also a Research Associate Professor in the Computer Science Department at USC. He received his Ph.D. from Carnegie Mellon University in 1991 and his BA from Harvard University in 1986. He is co-author (with Elaine Rich) of the textbook Artificial Intelligence. His main research interests are statistical natural language processing, machine translation, natural language generation, and decipherment.
November 15, 2002
Active learning with multiple views
Ion Muslea
USC-ISI
Labeling training data for machine learning algorithms is tedious, time consuming, and error prone. Consequently, it is of utmost importance to minimize the amount of labeled data that is required to learn a target concept. In the work presented here, I focus on reducing the need for labeled data in multi-view learning tasks. The key characteristic of multi-view learning tasks is that the target concept can be independently learned within different views (i.e., disjoint sets of features that are sufficient to learn the concept of interest). For instance, robot navigation is a 2-view learning task because a robot can learn to avoid obstacles based on either sonar or vision sensors.
In my dissertation, I make three main contributions. First, I introduce Co-Testing, which is an active learning algorithm that exploits multiple views. Co-Testing is based on the idea of learning from mistakes. More precisely, it queries examples on which the views predict a different label: if two views disagree, one of them is guaranteed to make a mistake. In a variety of real-world domains, from information extraction to text classification and discourse tree parsing, Co-Testing outperforms existing active learners.
Second, I show that existing multi-view learners can perform unreliably if the views are incompatible or correlated. To cope with this problem, I introduce a robust multi-view learner, Co-EMT, which interleaves semi-supervised and active multi-view learning. My empirical results show that Co-EMT outperforms existing multi-view learners on a wide variety of learning tasks.
Third, I introduce a view validation algorithm that predicts whether or not two views are adequate for solving a new, unseen learning task. View validation uses information acquired while solving several exemplar learning tasks to train a classifier that discriminates between tasks for which the views are adequate and inadequate for multi-view learning. My experiments on wrapper induction and text classification show that view validation requires a modest amount of training data to make high accuracy predictions.
Bio:
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