Computer & Information Science Department   Polytechnic University

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Algorithms and Complexity

(Profs. Aronov, Brönnimann, Chiang, Hellerstein, Suel, van Slyke, Wein)


The department has significant research strength in the algorithms area, with about half of our current faculty being actively involved in work ranging from fundamental theoretical problems in complexity to the experimental evaluation of algorithmic techniques.

Computational Geometry: Several faculty members are working on problems in the area of Computational Geometry, which is concerned with fundamental techniques for computing with geometric objects, and forms the theoretical basis for much work in applied areas such as Computer Graphics and Vizualization. In particular, Prof. Aronov has been studying a variety of questions in Combinatorial Geometry, i.e., the study of the combinatorial properties and resulting fundamental complexities of geometric problems. Prof. Brönnimann's work is concerned with theoretical issues in Computational Geometry as well as with practical problems arising in the context of programming libraries and object-oriented techniques for geometric computing. Prof. Chiang is studying geometric problems in graphics and visualization, with emphasis on I/O-efficient techniques for processing massive geometric data sets.

Approximation Algorithms & Combinatorial Optimization: Research in this area is concerned with precise and approximate solutions to hard algorithmic problems arising in many real-world situations, such as the optimal design of computer networks and other infrastructure, the scheduling of tasks to ensure the efficient use of limited resources, or the partitioning of data and work between nodes of a parallel machine. Two faculty members in our department, Profs. van Slyke and Wein, primarily focus on problems in this area. Prof. van Slyke has extensively worked on problems in combinatorial optimization theory and the design of information networks; among his recent works is a new distributed version of the simplex method, and a non-cooperative game model of flow control in computer networks. Prof. Wein has focused on scheduling and resource allocation problems, including general conversion techniques for transforming off-line into on-line scheduling algorithms, task scheduling in generalized communication networks, combinatorial problems in scheduling independent jobs in parallel machines, efficient algorithms for the dense assignment problem, and fractiling in parallel computation. Several other faculty members have also worked on approximation algorithms for a variety of flow, partitioning, and geometric problems.

Computational Learning Theory: Prof. Hellerstein is working on fundamental problems in the area of Computational Learning Theory, an area concerned with algorithms and fundamental limits for machine learning. Much of Prof. Hellerstein's work concerns query models of learning, in which the learner can ask questions of a teacher or can perform experiments. She has developed a number of efficient algorithms for learning particular classes of concepts in query models. She has also developed new techniques for determining when a class of concepts is learnable in query models, and for designing algorithms that remains efficient in the presence of irrelevant information. Prof. Hellerstein is particularly interested in the learnability of classes of Boolean functions and has done related research on characterizations of Boolean function classes. Recently, Prof. Hellerstein has also begun working on learning-based approaches in information retrieval.

Parallel and Distributed Algorithms: This area is concerned with the design of efficient algorithms for massively parallel machines, networks of workstations, and wide-area distributed networks. Two faculty members, Profs. Suel and Wein, have worked extensively in these areas. Prof. Suel's research has been concerned with the theoretical foundations of fixed-connection networks, such as meshes, hypercubes, or other types of graphs, and he has shown fundamental upper and lower bounds for sorting and communication problems on these networks. Another area of interest to him are models of parallel computation that allow and encourage the design of programs that are efficiently portable among different parallel architectures. Prof. Wein's research in this area is concerned with load balancing and partitioning techniques that schedule computations in a distributed environment in ways that perserve the locality properties of the underlying problem and adapt to changes in resource availability. Both faculty are also working with colleagues to apply their algorithmic results to real-life parallel computing problems, including simulations of particle and semiconductor physics, signal propagation, and nuclear stockpile testing.