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
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.