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--- shared:seminars_graphs [01.09.2019 10:39]
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+++ shared:seminars_graphs [08.09.2025 13:18] (текущий)
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 ====Спецсеминар "Графы на поверхностях и кривые над числовыми полями"====
----------
-**Семинар проходит по средам в ауд. 14-15 Главного здания, начало в 18:30.**
 ----
+**Семинар Георгия Борисовича Шабата регулярно работает с сентября 1991г. Обычно проходит по средам в ауд. 14-05 Главного здания. В настоящее время проводится частично он-лайн, с использованием технологии Zoom, начало в 18:30.** Программа семинара появляется также на нашей страничке на [[http://www.mathnet.ru/php/conference.phtml?option_lang=rus&eventID=12&confid=1881|Math-Net]]. Следите за обновлениями!
 ----
-**04.09.2019** ВНИМАНИЕ: начало в 18:00
+Для участия в он-лайн семинаре напишите elena -dot- kreines @ gmail -dot- com
-. Pálfia Miklós, On the recent advances in the multivariable theory
+**10.09.2025**
-of operator monotone functions and means
-Functional Analysis Research Group, Institute of Mathematics,
-University of Szeged, Hungary,
-Sungkyunkwan University, Korea
-Abstract:
+. Г.Б. Шабат, Граф К5 и поле из 5 элементов
-The origins of this talk go back to the fundamental theorem of Loewner
-in 1934 on operator monotone real functions and also to
-the hyperbolic geometry of positive matrices. Loewner's theorem
-characterizing one variable operator monotone functions has been
-very influential in matrix analysis and operator theory. Among others
-it lead to the Kubo-Ando theory of two-variable operator means
-of positive operators in 1980. One of the nontrivial means of the
-Kubo-Ando theory is the non-commutative generalization of the
-geometric mean which is intimately related to the hyperbolic,
-non-positively curved Riemannian structure of positive matrices.
-This geometry provides a key tool to define multivariable
-generalizations of two-variable operator means. Arguably the most
-important
-example of them all is the Karcher mean which is the center of mass on
-this manifold. This formulation enables us to define this mean
-for probability measures on the cone of positive definite matrices
-extending further the multivariable case. Even the infinite
-dimensional
-case of positive operators is tractable by abandoning the Riemannian
-structure in favor of a Banach-Finsler structure provided by
-Thompson's part metric on the cone of positive definite operators.
-This metric enables us to develop a general theory of means of
-probability measures defined as unique solutions of nonlinear operator
-equations on the cone, with the help of contractive semigroups
-of nonlinear operators. We also introduce the recently established
-structure theory of multivariable operator monotone functions
-extending the classical result
-of Loewner into the non-commutative multivariable realm of free
-functions, providing theoretically explicit closed formulas for our
-multivariable
-operator means.
-. F. Pakovich, COMMUTING RATIONAL FUNCTIONS REVISITED
+. Разное
-Ben Gurion University, Israel
-Abstract
+----
-Let A and B be rational functions on the Riemann sphere. The classical
+**[[[[:seminars_graphs_references|Полезные ссылки и другие ресурсы нашего семинара]]**
-Ritt theorem states that if A and B commute and do not have an iterate
-in common, then up to a conjugacy they are either powers, or Chebyshev
-polynomials, or Latt`es maps. This result however provides no
-information about commuting rational functions which do have a common
-iterate. On the other hand, non-trivial examples of such functions
-exist and were constructed already by Ritt. In the talk we present new
-results concerning this class of commuting rational functions. In
-particular, we describe a method which permits to describe all
-rational functions commuting with a given rational function.
 **Архив**
+[[[[:seminars_graphs_24_25|2024 - 2025 учебный год]]
+[[[[:seminars_graphs_23_24|2023 - 2024 учебный год]]
+[[[[:seminars_graphs_22_23|2022 - 2023 учебный год]]
+[[[[:seminars_graphs_21_22|2021 - 2022 учебный год]]
+[[[[:seminars_graphs_20_21|2020 - 2021 учебный год]]
+[[[[:seminars_graphs_19_20|2019 - 2020 учебный год]]
 [[[[:seminars_graphs_18_19|2018 - 2019 учебный год]]