Constructing group actions on quasi-trees – Koji Fujiwara – ICM2018
Topology Invited Lecture 6.12 Constructing group actions on quasi-trees Koji Fujiwara Abstract: A quasi-tree is a geodesic metric space quasi-isometric to a tree. We give a general construction of many actions of groups on quasi-trees. The groups we can handle include non-elementary hype
From playlist Topology
Bertrand Rémy: Bruhat-Tits theory of quasi-split groups
The goal of this lecture is to present the construction of the Bruhat-Tits buildings attached to a quasi-split (that is admitting a Borel subgroup) semisimple group G defined over an henselian discretly valued field K and also the construction of the parahoric group schemes parametrized by
From playlist Lie Theory and Generalizations
Jean Michel : Quasisemisimple classes
Abstract: This is a report on joint work with François Digne. Quasisemisimple elements are a generalisation of semisimple elements to disconnected reductive groups (or equivalently, to algebraic automorphisms of reductive groups). In the setting of reductive groups over an algebraically c
From playlist Lie Theory and Generalizations
A quick definition of groups on the periodic table. Chem Fairy: Louise McCartney Director: Michael Harrison Written and Produced by Kimberly Hatch Harrison ♦♦♦♦♦♦♦♦♦♦ Ways to support our channel: ► Join our Patreon : https://www.patreon.com/socratica ► Make a one-time PayPal donation
From playlist Chemistry glossary
Now that we have defined and understand quotient groups, we need to look at product groups. In this video I define the product of two groups as well as the group operation, proving that it is indeed a group.
From playlist Abstract algebra
Abstract Algebra: We define the notion of a subgroup and provide various examples. We also consider cyclic subgroups and subgroups generated by subsets in a given group G. Example include A4 and D8. U.Reddit course materials available at http://ureddit.com/class/23794/intro-to-group-
From playlist Abstract Algebra
Kevin Whyte, Lecture 2: Infinite Groups in Geometric Topology, Part 2
31st Workshop in Geometric Topology, University of Wisconsin-Milwaukee, June 13, 2014
From playlist Kevin Whyte: 31st Workshop in Geometric Topology
Dihedral Group (Abstract Algebra)
The Dihedral Group is a classic finite group from abstract algebra. It is a non abelian groups (non commutative), and it is the group of symmetries of a regular polygon. This group is easy to work with computationally, and provides a great example of one connection between groups and geo
From playlist Abstract Algebra
Group theory 7: Semidirect products
This is lecture 7 of an online course on group theory. It covers semidirect products and uses them to classify groups of order 6.
From playlist Group theory
Daniel Greb: Structure theory for singular varieties with trivial canonical divisor
Recording during the meeting "Varieties with Trivial Canonical Class " the April 09, 2020 by the Centre International de Rencontres Mathématiques (Marseille, France) Filmmaker: Guillaume Hennenfent Find this video and other talks given by worldwide mathematicians on CIRM's Audiovisual Math
From playlist Virtual Conference
Gopal Prasad: Descent in Bruhat-Tits theory
Bruhat-Tits theory applies to a semisimple group G, defined over an henselian discretly valued field K, such that G admits a Borel K-subgroup after an extension of K. The construction of the theory goes then by a deep Galois descent argument for the building and also for the parahoric grou
From playlist Algebraic and Complex Geometry
Kęstutis Česnavičius - Grothendieck–Serre in the quasi-split unramified case
Correction: The affiliation of Lei Fu is Tsinghua University. The Grothendieck–Serre conjecture predicts that every generically trivial torsor under a reductive group scheme G over a regular local ring R is trivial. We settle it in the case when G is quasi-split and R is unramified. To ov
From playlist Conférence « Géométrie arithmétique en l’honneur de Luc Illusie » - 5 mai 2021
Yael Algom-Kfir: Conformal dimension and free by cyclic groups
Let $G$ be a hyperbolic group. Its boundary is a topological invariant within the quasi-isometry class of $G$ but it is far from being a complete invariant, e.g. a random group at density ¡1/2 is hyperbolic (Gromov) and its boundary is homeomorphic to the Menger curve (Dahmani-Guirardel-Pr
From playlist Topology
Inner & Outer Semidirect Products Derivation - Group Theory
Semidirect products are a very important tool for studying groups because they allow us to break a group into smaller components using normal subgroups and complements! Here we describe a derivation for the idea of semidirect products and an explanation of how the map into the automorphism
From playlist Group Theory
Supercuspidal L-packets - Tasho Kaletha
Tasho Kaletha Member, School of Mathematics March 21, 2011 For more videos, visit http://video.ias.edu
From playlist Mathematics
Ana Caraiani - 3/3 Shimura Varieties and Modularity
We discuss vanishing theorems for the cohomology of Shimura varieties with torsion coefficients, under a genericity condition at an auxiliary prime. We describe two complementary approaches to these results, due to Caraiani-Scholze and Koshikawa, both of which rely on the geometry of the H
From playlist 2022 Summer School on the Langlands program
Ahlfors-Bers 2014 "Rigidity of Teichmüller space"
Kasra Rafi (University of Toronto): We study the large scale geometry of Teichmüller space equipped with the Teichmüller metric. We show that, except for low complexity cases, any self quasi-isometry of Teichmüller space is a bounded distance away from an isometry of Teichmüller space. Our
From playlist The Ahlfors-Bers Colloquium 2014 at Yale
Visual Group Theory, Lecture 3.5: Quotient groups
Visual Group Theory, Lecture 3.5: Quotient groups Like how a direct product can be thought of as a way to "multiply" two groups, a quotient is a way to "divide" a group by one of its subgroups. We start by defining this in terms of collapsing Cayley diagrams, until we get a conjecture abo
From playlist Visual Group Theory
Dustin Clausen - Toposes generated by compact projectives, and the example of condensed sets
Talk at the school and conference “Toposes online” (24-30 June 2021): https://aroundtoposes.com/toposesonline/ The simplest kind of Grothendieck topology is the one with only trivial covering sieves, where the associated topos is equal to the presheaf topos. The next simplest topology ha
From playlist Toposes online