Weekly Calendar

February 19-23, 2001

Monday	Tuesday	Wednesday	Thursday	Friday

Items for inclusion in the Weekly Calendar should be submitted via e-mail to Hilda Britt. Deadline for inclusion in the Weekly Calendar is 5 p.m. Thursdays. Speakers are encouraged to provide abstracts.

241 Altgeld Hall, 3:00 p.m.

GEOMETRIC POTPOURRI SEMINAR

Dr. Eric Weisstein, Wolfram Research, Inc.

An interactive catalog of polyhedra for the web

Abstract: I will present the prototype of a new website devoted to cataloging polyhedra and their analytic properties. The soon-to-be-unveiled website, located at http://polyhedra.wolfram.com/, seeks to calculate and enumerate all "interesting" properties (e.g., volume, symmetry group, etc.) of common classes of polyhedra (e.g., Archimedeans, Archimedean duals, Archimedean-dual compounds, Pyramids, Johnson solids, etc.), in exact form whenever possible. Interactive versions of the solids and their wireframes (as well as nets) are also provided. However, many solids currently lack complete information. Input from the audience on the particular subjects of algorithms for computing missing properties or suggestions of additional classes of polyhedra to include in the site will be gratefully received.

345 Altgeld Hall, 3:00 p.m.

GRAPH THEORY AND COMBINATORICS

Micha Karonski, Faculty of Math. and Comp. Sci., Adam Mickiewicz University, Poznan, Poland, Dept. of Math. and Comp. Sci., Emory University, Atlanta, Georgia

Distributed graph algorithms

Abstract: In our talk we are concerned with distributed graph algorithms, where a synchronous, message-passing network without shared memory is to compute a function of its own topology. In such a distributed network, the cost of sending a message between two nodes is proportional to their distance in the network. Since sending messages to far-away nodes is expensive, it is desirable that computation be based only on information available locally. This locality constraint can be quite severe when one must compute a global function of input data that are spread across the network; it represents a challenge for algorithmic design.

This communication problem is completely neglected in the popular pram model. There, the existence of a shared memory which can be accessed in unit time allows fast collection and dissemination of data among the processors. Once this assumption is removed and the cost of communication is taken into consideration, several computational problems which were easily solvable suddenly become hard or unsolvable efficiently, especially if one is seeking deterministic solutions. Here we focus our attention on computing maximal matchings and f-matchings and also on graph coloring problems.

114 CSRL, 3:00 p.m.

TOPICS IN SYSTEMS SEMINAR

Eytan Modiano, Laboratory for Information and Decision Systems, Massachusetts Institute of Technology

Architectural considerations in the design of WDM-based optical networks

Abstract: This talk will highlight recent work, as well as future research directions, in Wavelength Division Multiplexing (WDM) networks. It is motivated by the design of high capacity optical networks for the Next Generation Internet (NGI). An important goal of the architecture for the NGI is to reduce the cost of electronics in the network by supporting Internet traffic directly over the WDM layer (IP over WDM). Some of the issues discussed include: network reconfiguration algorithms that improve network capacity by altering the network logical topology in response to changes in traffic conditions; traffic grooming algorithms to minimize the cost of electronics in the network; algorithms for joint electronic and optical layer protection; and optical flow switching algorithms for bypassing the electronics in the network.

245 Altgeld Hall, 4:00 p.m.

MATHEMATICS IN SCIENCE AND SOCIETY

Rick Stone Senior Consultant, Operations Research, Northwest Airlines Operations Research Unit

Airline Planning Problems

Abstract: In many ways a major airline can be viewed as one large planning problem which is usually approached as many interdependent smaller (but still imposing) planning problems. The list of things which need planning seems endless: crews, reservation agents, luggage, flights, through trips, maintenance, gates, inventory, equipment purchases. Each planning problem has its own considerations, its own complexities, its own set of time horizons, its own objectives, but all are interrelated.

In this talk, we will briefly look at a few of these airline planning problems. For each, we will outline the basic problem, considerations, and objectives. In addition, for each planning problem we review, we will discuss how one might quantitatively approach the problem so as to intelligently support the planning process.

Refreshments at 3:15 p.m. in Room 321 Altgeld Hall