October 15, 2013  
                      What is tropical mathematics? 
                   
                   
                    In tropical mathematics the usual laws of 
                      algebra are changed, the subtraction is forbidden, the division 
                      is always permitted, and 1+1 is equal to 1. Analogs of usual 
                      geometric shapes like lines, circles etc. are replaced by 
                      new figures composed of pieces of lines. I will try to explain 
                      basics of tropical algebra and geometry, its relation with 
                      more traditional domains, and its role in mirror symmetry 
                      which is a remarkable duality originally discovered in string 
                      theory about 20 years ago. 
                   
                  October 16, 2013 
                    Quivers, cluster varieties and integrable systems 
                   
                     I'll describe a new approach to cluster varieties and 
                      mutations based on  
                      scattering diagrams and wall-crossing formalism. The central 
                      role here is played by certain canonical transformation 
                      (formal change of coordinates) associated with arbitrary 
                      quiver. Also, a complex algebraic integrable system under 
                      some mild conditions produces a quiver, and the associated 
                      canonical transformation is a birational map. 
                   
                  October 17, 2013 
                    Fukaya category meets Bridgeland stability 
                  
                    Bridgeland's notion of stability in triangulated categories 
                      is believed to be a mathematical encoding of D-branes in 
                      string theory. I'll argue (using physics picture) that partially 
                      degenerating categories with stability should be described 
                      as a mixture between symplectic geometry and pure algebra. 
                      Spectral networks of Gaiotto, Moore and Neitzke appear as 
                      an example. 
                   
                    
                 |