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                  Undergraduate Network Meeting: 
                    Research in Combinatorics 
                  November 27 
                    10:00 a.m. - 4:00 p.m.  
                    at the University of Waterloo 
                    Mathematics and Computer Science Building (MC) 
                    Room MC1085
                  Speakers: 
                    Balazs Szegedy (Toronto) 
                    Levent Tuncel (Waterloo) 
                    Dave Wagner (Waterloo)
                    Abstracts 
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                Organizers: Richard Cerezo (rcerezo(at)fields.utoronto.ca), 
                  Sarah Sun, and Yifan Li (pmclub(at)gmail.com) 
                  Faculty Advisor: Matthias Neufang | 
               
             
              
            
            Undergraduate Network includes a series of mathematical talks aimed 
              at undergraduates, and organized into a network involving the local 
              universities. We will be stating with trial run of four events for 
              next year with faculty members as consultants. 
             
            Talks: 
              Levent Tuncel, University of Waterloo 
              A Guided tour of Mathematical Optimization 
              We will start the talk with linear optimization problems (optimizing 
              a linear function subject to linear inequalities). This will take 
              us to convex geometry, we will see an open problem related to the 
              combinatorics of polytopes (and computational complexity) as well 
              as some theorems of Caratheodory and Helly. Then, we will move on 
              to hyperplane separation theorem and duality theory of convex optimization. 
              We will introduce the semidefinite optimization problem (a class 
              of convex optimization problems with matrices as the variables). 
              Our path will lead us to optimization problems cast over multivariate 
              polynomial inequalities and we will conclude by making a connection 
              to real algebraic geometry and mentioning a new area of research 
              ``convex algebraic geometry.'' Many open problems will be sprinkled 
              throughout the presentation. 
               
              Dave Wagner, University of Waterloo 
              Integer flows in graphs and regular matroids 
              Imagine a graph G as a collection of pipes (the edges) and junctions 
              (the vertices). Water currents can flow through these pipes at many 
              different rates as long as mass is conserved at each junction. The 
              set of all flows is in fact a real inner product space. The set 
              of vectors with integer coordinates is the lattice ?(G) of integer 
              flows of G. 
              If one forgets the coordinates of the integer flows and remembers 
              only the geometric "shape" of the whole lattice ?(G), 
              can one recover the original graph? There are a few obvious ambiguities, 
              and in 1997 it was conjectured that these are the only ones. In 
              2008, together with my undergraduate research assistant Yi Su, we 
              proved this conjecture. 
              I will sketch the main ideas of our proof, which is most naturally 
              cast in terms of regular matroids. Of course, I will assume no knowledge 
              of matroid theory, and will begin by explaining what regular matroids 
              are and why they are as good as graphs in many ways 
               
              Balazs Szegedy, University of Toronto 
              Topics in Additive Combinatorics 
            Final List of Participants:
            
               
                | Full Name | 
                University/Affiliation | 
               
               
                | Aftab, Umar | 
                University of Waterloo | 
               
               
                | Ben-David, Shalev | 
                University of Waterloo | 
               
               
                | Bering, Edgar | 
                University of Waterloo | 
               
               
                | Boyko, Mariya | 
                University of Toronto (Mississauga) | 
               
               
                | Bradley, Nick | 
                Queen's University | 
               
               
                | Burton, Peter | 
                University of Toronto | 
               
               
                | Cerezo, Richard | 
                University of Toronto | 
               
               
                | Chammah, Tarek | 
                University of Waterloo | 
               
               
                | Chow, Kevin | 
                University of Waterloo | 
               
               
                | Dosseva, Annamaria | 
                University of Waterloo | 
               
               
                | Drabek, Rafal | 
                  | 
               
               
                | Dranovski, Anne | 
                University of Toronto | 
               
               
                | Du, Chen Fei | 
                University of Waterloo | 
               
               
                | Duong, Adrian | 
                University of Waterloo | 
               
               
                | Kabir, Ifaz | 
                University of Waterloo | 
               
               
                | Lacharité, Marie-Sarah | 
                University of Waterloo | 
               
               
                | Li, Bing | 
                University of Toronto | 
               
               
                | Li, Yifan | 
                University of Waterloo | 
               
               
                | Liang, Jiayu | 
                University of Toronto | 
               
               
                | Ma, David | 
                University of Waterloo | 
               
               
                | Mauger, Philippe | 
                University of Waterloo | 
               
               
                | McLaughlin, David | 
                University of Waterloo | 
               
               
                | Mohammadi, Mohammadreza | 
                University of Toronto | 
               
               
                | Ng, Keith | 
                University of Toronto | 
               
               
                | Pashley, Bryanne | 
                University of Waterloo | 
               
               
                | Pistone, Jamie | 
                University of Toronto | 
               
               
                | Poon, Alexander | 
                McMaster University | 
               
               
                | Rhee, Donguk | 
                University of Waterloo | 
               
               
                | Sagatov, Sergei | 
                University of Toronto | 
               
               
                | Schaeffer, Luke | 
                University of Waterloo | 
               
               
                | Tham, Emin | 
                  | 
               
               
                | Wesolowski, Michael | 
                University of Waterloo | 
               
               
                | Yeung, Tiffany | 
                University of Toronto | 
               
               
                | Zhu, Ren | 
                University of Waterloo | 
               
             
            
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