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<span style="font-size:11.5pt;font-family:Helvetica;color:black;font-weight:normal">Dear all,<o:p></o:p></span></h4>
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<span style="font-size:11.5pt;font-family:Helvetica;color:black;font-weight:normal">Lots of events this week!<o:p></o:p></span></h4>
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<span style="font-size:11.5pt;font-family:Helvetica;color:black;font-weight:normal">Tuesday, which is either tomorrow or today depending when you read your email, we have a guest in the AG from Bonn.<o:p></o:p></span></h4>
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<span style="font-size:11.5pt;font-family:Helvetica;color:black">AG: 12-03-2024: 11:00 in Maryam: Karandeep Singh (Bonn) : Stability problems and differential graded Lie algebras</span><o:p></o:p></h4>
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<span style="font-size:9.0pt;font-family:Helvetica;color:black">Abstract: Stability problems appear in various forms throughout geometry and algebra. For example, given a vector field $X$ on a manifold that vanishes in a point, when do all nearby vector fields
also vanish somewhere? As an example in algebra, we can consider the following question: Given a Lie algebra $\mathfrak g$, and a Lie subalgebra $\mathfrak h$, when do all deformations of the Lie algebra structure on $\mathfrak g$ admit a Lie subalgebra close
to $\mathfrak h$? I will show that both questions are instances of a general question about differential graded Lie algebras, and under a finite-dimensionality condition which is satisfied in the situations above, I will give a sufficient condition for a positive
answer to the general question. I will then discuss the application to fixed points of Lie algebra actions.</span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">This Friday we have a DDT&G with a guest from Columbia university (New York)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
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<b><span style="font-size:11.5pt;font-family:Helvetica;color:black">15-03-2024 14:00-16:30 Amsterdam NU building 9-A46: <a href="https://www.math.columbia.edu/~flin/"><span style="color:blue">Francesco Lin </span></a>(Columbia): Topology of the Dirac equation
on spectrally large three-manifolds<o:p></o:p></span></b></p>
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<span style="font-size:9.0pt;font-family:Helvetica;color:black">Abstract: In the first talk, I will review the classical work of Atiyah and Singer describing the homotopy type of the family of Dirac operators on a spin Riemannian manifold, and its consequences
regarding metrics of positive scalar curvature. In the second talk, I will discuss how one can exploit the Seiberg-Witten equations and Floer theory to obtain more detailed information about the structure of the family in the case of a three-manifold for which
the spectral gap of the Hodge Laplacian on coexact 1-forms is large compared to the curvature. For concreteness, we will have a special focus on the case of the n-torus throughout the talks.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">I hope to see you both. As always, your students are also very welcome to attend!<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Best,<br>
Thomas</span><o:p></o:p></p>
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