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This session will represent an introduction to several more advanced topological topics that are important in different branches of mathematics and physics.

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We will discuss algebraic properties of knot surgery diagrams that turn out to be useful tools to simplify the description of a three manifod.

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We will focus this lecture on the concept of homology and its relation to the handle decomposition of manifolds.

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I will review the structure of the fermionic Z2xZ2 orbifolds that produced a large space of phenomenological three generation models. I will discuss the trial and error old school method that gave rise to the first known string derived MSSM models, as well as the more modern classification methods that enables the analysis of large spaces of vacua and extraction of some of the global properties underlying them, e.g. spinor--vector duality. I will discuss a new direction of research that was initiated over the past year. Since the mid-eighties it is known that in addition to the ten dimensional tachyon free heterotic-string vacua there exist tachyonic ten dimensional vacua. In the supersymmetric and non-supersymmetric tachyon free cases the ten dimensional tachyon are projected out by the same projection. I will discuss the construction of phenomenological tachyon free models starting from the tachyonic 10D vacua and their particular features.

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Title: How Domain Walls of N=1, D=4 SYM look like

Speaker: Dmitri Sorokin, University of Padua, Italy

Abstract: We review main features of the pure N=1, D=4 SYM with the gauge group SU(N) and its effective description by the Veneziano-Yankielowicz generalized sigma-model. We then indicate that the construction of BPS domain walls interpolating between different SYM vacua requires the presence of a dynamical membrane source. We will show how such a membrane is coupled to the SYM and present the explicit form of BPS domain walls which it creates in the Veneziano-Yankielowicz effective theory. In particular, we will describe 1/2 BPS domain wall configurations with |k| less than or equal to N/3, where k is the membrane charge that sets the "distance" between two distinct SUSY vacua.

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General-audience geek-out Zoom talk.

Speaker: Yasha Neiman.

Title: "Reductionism, physics, mathematics and the mind".

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Title: Quantization of folded strings in non-critical dimensions

Speaker: Dorin Weissmann

Abstract: I will talk about some problems that arise when attempting to quantize rotating strings semiclassically, in the critical and non-critical dimensions. The problems are divergences associated with folding points in the string. A rotating closed string is a basic system that suffers from this problem, and I show how we deal with it by treating the fold as a boundary and placing mass terms there. Based on an upcoming paper with J. Sonnenschein.

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This is the first seminar in the online seminar series OIST Neuroscience Online Seminar (ONOS). Dr. Lukas Ian Schmitt is a team leader of the distributed cognitive processing laboratory in RIKEN. Please join us using the following link

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CFF internal seminar

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Seminar for general audience, about mankind's discovery of magic.

Speaker: Yasha Neiman.

Title: "The spiritual art of Calculus and the union of Heaven and Earth".