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Cotygodniowe seminarium badawcze
2019-05-28, godz. 16:15, 3180
Genevieve Walsh (Tufts University)
Incoherence of many free by free groups
A group is coherent if every finitely generated subgroup is finitely presented. Free by cyclic groups are known to be coherent by work of Feighn and Handel. We show that many free by free groups (where the free groups have rank at least 2) are incoherent. Our techniques use fibrations of the group. ...
2019-05-07, godz. 16:15, 3180
Mahan Mj (Tata Institute of Fundamental Research)
Coarse Extrinsic Geometry and surface-by-free groups
JOINT WITH SIMONS SEMESTER The notion of distortion of finitely generated subgroups H of finitely generated groups G, introduced by Gromov, is a first step towards studying extrinsic geometry of subgroups in the coarse setup. When the group and subgroup are hyperbolic, finer information can be ...
2019-04-30, godz. 16:15, 3180
Marcin Sabok (McGill University, IMPAN)
JOINT WITH SIMONS SEMESTER In 1925, Tarski asked if a disc in the plane and a square of the same area are equidecomposable, i.e. if the disc can be partitioned into finitely many pieces which can be rearranged by isometries of the plane to form a square. In 1990, Laczkovich showed that Tarski&...
2019-04-16, godz. 16:15, 4070
Michael W. Davis (Ohio State University)
The action dimension of a discrete group
Colloquim joint with Simons Semester A space is called a K(G,1) if its fundamental group is G and if its universal cover is contractible. The geometric dimension of G is the smallest dimension of a model for K(G,1) by a cell complex. Its action dimension is the smallest dimension ...
2019-04-02, godz. 16:15, 3180
Pierre Pansu (Universite Paris-Sud)
Aspects of geometric group theory: growth, isoperimetry, Lp-cohomology
SIMONS SEMESTER COLLOQUIUM The growth and isoperimetry of finitely generated groups have been among its early interests. We shall show how they lead to today’s cohomological methods, notions of negative curvature and rigidity problems. https://www.impan.pl/en/activities/banach-center/confere...
2019-03-26, godz. 16:15, 4070
Michał Lech (MIMUW)
Grupa monodromii osobliwości i automorfizmy diagramów Dynkina
2019-02-26, godz. 16:15, 4070
Grzegorz Banaszak (UAM)
Algebraic Sato-Tate group for motives
In my talk I will explain the notion of equidistibution, in particular the Sato-Tate conjecture concerning the equidistribution of Frobenius elements in l-adic representations. In particular I will show how to apply the motivic Galois group to construct Algebraic Sato-Tate group to study...
2019-01-22, godz. 16:15, 4070
Rafał Lutowski (UG)
Spin struktury płaskich rozmaitości typu diagonalnego
Zaprezentujemy czysto kombinatoryczny opis klas Stiefela-Whitneya płaskich rozmaitości z diagonalną reprezentacją holonomii. Używając tego opisu, dla każdej liczby całkowitej d większej od 1 skonstruujemy orientowalną płaską rozmaitość z elementarną abelową grupą holonomii rangi d, ...
2019-01-15, godz. 16:15, 4070
Krzysztof Ziemiański (MiMUW)
2018-12-11, godz. 16:15, 4070
Jan Spaliński (PW)
