UIUC Dept. of Mathematics Seminar Calendar

     August 2003           September 2003          October 2003    
 Su Mo Tu We Th Fr Sa   Su Mo Tu We Th Fr Sa   Su Mo Tu We Th Fr Sa
                 1  2       1  2  3  4  5  6             1  2  3  4
  3  4  5  6  7  8  9    7  8  9 10 11 12 13    5  6  7  8  9 10 11
 10 11 12 13 14 15 16   14 15 16 17 18 19 20   12 13 14 15 16 17 18
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 24 25 26 27 28 29 30   28 29 30               26 27 28 29 30 31   
 31

Friday, September 5, 2003

Geometry and Algebra of Computer Vision
2:00 pm in 2369 Beckman Institute, Friday, September 5, 2003

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Submitted by rmfossum.

Robert Fossum and Yi Ma [email] (UIUC Math/Beckman/ECE)
CANCELLED
Abstract: This RAP will be held every Friday afternoon from 2 to 3. The purpose is to consider the mathematical underpinnings of computer vision (CV) as well as recent advances in CV. Graduate students and faculty from all areas are welcome. Also speakers are incouraged to volunteer.

Model Theory Seminar
4:00 pm in 143 Altgeld Hall, Friday, September 5, 2003

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Submitted by jamoreno.

Kobi Peterzil [email] (Math Haifa visiting UIUC)
Torsion-free groups in o-minimal structures
Abstract: (joint work with Sergei Starchenko) In the category of Real Lie groups, every abelian connected group is isomorphic to R^n+S^k, where R is (R,+) and S is the circle group. In the category of semialgebraic sets and maps such a result fails, since (R,+) is not semialgebraically isomorphic to the multiplicative group of {R>0}. Moreover, there are semialgebraic abelian compact groups of dimension n which cannot be written (in the semialgebraic langauge) as a direct sum of circle groups. We prove: Assume that a group G is either semialgerbaic or definable in R_an, or definable in the expansion of R_an by power functions. If G is abelian, connected and torsion-free, then it is definably isomorphic to (R,+)^n+(R>0,*)^k. (Where "definably" means in the same structure where G is definable).