impan seminar:

working group in applications of set theory



Announcement: Due to the epidemic situation the meetings of the seminar are suspended until the situation gets better. In the meantime we suggest participating in an online lecture on the interaction of set theory and C*-algebras given by Ilijas Farah as a part of Fields Academy Graduate Courses. The description of this course entitled "Massive C*-algebras" can be found here. To register go here.

Previous talks this semester:
Postponed:
Kamil Ryduchowski (UW): Antiramsey coloring of pairs

Abstract: "We present a fundamental theorem by Todorcevic, stating that there exists a coloring of the complete graph of the first uncountable cardinality in uncountably many colors without an uncountable monochromatic clique. We also discuss other results of Todorcevic of similar nature, which are in some sense multidimensional variants of that coloring."


Literature:

  • Todorcevic, Stevo, Partitioning pairs of countable ordinals. Acta Math. 159 (1987), no. 3-4, 261--294.
  • Velleman, Dan, Partitioning pairs of countable sets of ordinals. J. Symbolic Logic 55 (1990), no. 3, 1019--1021.


29.10.2020, Thursday 15.15, room 106
Piotr Koszmider (IMPAN): An application of Schreier's family

Abstract: "This is an introduction to basic facts on the isomorphic classification of separable Banach spaces C(K). As an example we show an ingenious argument by Józef Schreier which uses the combinatorial structure of the ordinal ωω to understand some Banach spaces and to resolve a question of S. Banach."


Literature:

  • On the classification of spaces C[0,α] see Chapter 2.6 of Hajek, Petr; Montesinos Santalucia, Vicente; Vanderwerff, Jon; Zizler, Vaclav Biorthogonal systems in Banach spaces. CMS Books in Mathematics/Ouvrages de Mathematiques de la SMC, 26. Springer, New York, 2008.
  • A deep modern versions of Milutin's theorem can be found in: Argyros, Spiros A.; Arvanitakis, Alexander D. A characterization of regular averaging operators and its consequences. Studia Math. 151 (2002), no. 3, 207–226.
  • Schreier's argument is Exercise 19.3.9 (F) in Semadeni, Zbigniew Banach spaces of continuous functions. Vol. I. Monografie Matematyczne, Tom 55. PWN—Polish Scientific Publishers, Warsaw, 1971.

22.10.2020, Thursday 15.15, room 106
Piotr Koszmider (IMPAN): Eberlein compact spaces, WCG Banach spaces and ladder systems.

Abstract: "This is an introduction to basic facts and examples concerning Eberlein compact spaces (compact subspaces of Banach spaces with the weak topology) and WCG Banach spaces which are associated with each other. As the main set-theoretic example we will consider ladder system spaces on ω1 and spaces induced by almost disjoint families."


Literature:

  • On the weak and weak* topologies see Chapter 3 of Fabian, Marian; Habala, Petr; Hajek, Petr; Montesinos Santalucia, Vicente; Pelant, Jan; Zizler, Vaclav Functional analysis and infinite-dimensional geometry. CMS Books in Mathematics/Ouvrages de Mathematiques de la SMC, 8. Springer-Verlag, New York, 2001.
  • On EC and WCG spaces see Chapters 11 and 12 of Fabian, Marian; Habala, Petr; Hajek, Petr; Montesinos Santalucía, Vicente; Pelant, Jan; Zizler, Václav Functional analysis and infinite-dimensional geometry. CMS Books in Mathematics/Ouvrages de Mathematiques de la SMC, 8. Springer-Verlag, New York, 2001.
  • The proof that C(K) is Lindelof in the weak topology, where K is the ladder system space is here: Pol, Roman A function space C(X) which is weakly Lindelof but not weakly compactly generated. Studia Math. 64 (1979), no. 3, 279–285.
  • A survey of results on the spaces KA, where A is an almost disjoint family of subsets of N: Hrusak, Michael Almost disjoint families and topology. Recent progress in general topology. III, 601–638, Atlantis Press, Paris, 2014.
  • A survey of results on the spaces KA, where A is an almost disjoint family of subsets of N: Hernandez-Hernandez, F.; Hrusak, M. Topology of Mrowka-Isbell spaces. Pseudocompact topological spaces, 253–289, Dev. Math., 55, Springer, Cham, 2018.
  • Some results on the spaces KA, where A is an almost disjoint family of subsets of uncountable sets: Ferrer, Jesus; Koszmider, Piotr; Kubis, Wieslaw Almost disjoint families of countable sets and separable complementation properties. J. Math. Anal. Appl. 401 (2013), no. 2, 939–949.








Talks in the second semester of 2019-20.

Talks in the first semester of 2019-20.

Talks in the second semester of 2018-19.

Talks in the first semester of 2018-19.

Talks in the second semester of 2017-18.

Talks in the first semester of 2017-18.

Talks in the second semester of 2016-17.

Talks in the first semester of 2016-17.

Talks in the second semester of 2015-16.

Talks in the first semester of 2015-16.

Talks in the second semester of 2014-15.

Talks in the first semester of 2014-15.

Talks in the second semester of 2013-14.

Talks in the first semester of 2013-14.

Talks in the second semester of 2012-13.

Talks in the first semester of 2012-13.

Talks in the second semester of 2011-12.

Talks in the first semester of 2011-12.

Time and place: Thursdays 15.15-17.00 pm, room 106, Sniadeckich 8



Due to epidemic regulations at IM PAN the seminar must be limited to five participants and thus is a closed event as far as now.

The scope of the seminar: Set-theoretic combinatorial and topological methods in diverse fields of mathematics, with a special emphasis on abstract analysis like Banach spaces, Banach algebras, C*-algebras, Here we include both the developing of such methods as forcing, descriptive set theory, Ramsey theory as well as their concrete applications in the fields mentioned above.

Working group style: We will make efforts so that this seminar has more a working character rather than the presentation style. This means that we encourage long digressions, discussions, background preparations and participation of everyone. We would like to immerse ourselves into the details of the mathematical arguments studied. Also the talks are usualy devoted to research in progress or fascinating results leading to some project not yet resolved. While ready final results could be presented at other seminars at IM PAN or UW.

Participants this semester so far:

  • Jakub Andruszkiewicz, (PH.D. student UW)
  • Damian Głodkowski (PH.D. student UW)
  • Piotr Koszmider (IM PAN)
  • Kamil Ryduchowski (M.A. student UW)
  • Krzysztof Zakrzewski (PH.D. student UW)
Forthcoming talks :