Mon, February 10, 2020
Public Access


Category:
Category: All

10
February 2020
Mon Tue Wed Thu Fri Sat Sun
          1 2
3 4 5 6 7 8 9
10 11 12 13 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29  
8:00am  
9:00am  
10:00am  
11:00am  
12:00pm  
1:00pm  
2:00pm  
3:00pm  
4:00pm [4:00pm] Marie-Francoise Roy:University of Rennes:Mathematics Colloquium.
Description:
Mathematics Colloquium. Speaker: Marie-Francoise Roy. Affiliation: University of Rennes. Date and Time: Monday 10 February, 04:00 pm - 05:00 pm. Venue: Room 216, Department of Mathematics. Title: Hilbert 17th problem: classical proof and recent effectivity results. Abstract: Hilbert 17th problem is asking whether a non negative polynomial is always a sum of squares. We discuss Artin’s (1927) positive answer to this problem and explain why this answer did not provide an effective method for constructing the sum of squares. We describe primitive recursive effective results obtained by Kreisel and his students in the fifties. Finally we explain the first elementary recursive degree bound we obtain, a tower of five exponentials. A precise bound in terms of the number and degree of the polynomials and their number of variables is provided. This is a joint work with Henri Lombardi and Daniel Perrucci.

5:00pm  
6:00pm