Schriftzug: Fachbereich Mathematik 
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Berlin-Hamburg-Seminar am 26.6.2017

Vsevolod Shevchishin (Olsztyn) On symplectic mapping class group of rational 4-manifolds: Presentation in the cases Dl and E5

The symplectic mapping class group Symp(X,ω) is the group of symplectomorphisms of (X,ω) modulo symplectic isotopies. It appears that Symp(X,ω) depends not only on the manifold X, but also on the symplectic form. In my talk I describe two special types of symplectic forms on rational 4-manifold (l-fold blow-ups of CP2), called Dl and El. For symplectic forms of those types I describe a construction which allows to find a natural geometric presentation of the group Symp(X,ω), and make a calculation for the types Dl and E5.

Kyler Siegel (MIT) Subflexible symplectic manifolds and deformed symplectic invariants

One school of symplectic geometers believes that every symplectic creature either (a) satisfies an h principle or (b) has some nontrivial pseudoholomorphic curve invariant. Recent years have considerably progressed our understanding of the objects constituting category (a). In this talk, I will construct a class of examples, called "subflexible", which lie surprisingly close to the interface between (a) and (b). I will explain what types of symplectic invariants one must use to properly understand these examples and place them in category (b). Time permitting, I will end with some speculations about future symplectic invariants and exotica.



 
  Seitenanfang  Impressum 2017-06-13, Janko Latschev