Scientific Seminar
at the Department of Algebra, Topology and Foundations of Mathematics
Ivan Franko National University of Lviv
Archive for (2020/2021) academic year



Topological
Algebra

October 7, 2020 O. Gutik
  • On the monoid of cofinite partial isometries of $\mathbb{N}$ with a bounded finite noise

    We extend results of the papers [Carl Eberhart and John Selden, On the Closure of the Bicyclic Semigroup, Transactions of the American Mathematical Society, Vol. 144 (Oct., 1969), pp. 115-126 ] and [M. O. Bertman and T. T. West, Conditionally Compact Bicyclic Semitopological Semigroups, Proceedings of the Royal Irish Academy. Section A: Mathematical and Physical Sciences Vol. 76 (1976), pp. 219-226] for the monoid $\mathbf{I}\mathbb{N}_{\infty}^{\textbf{g}[j]}$ of cofinite partial isometries of $\mathbb{N}$ with a bounded finite noise for any positive integer $j$. In particular we show that for any positive integer $j$ every Hausdorff shift-continuous topology $\tau$ on $\mathbf{I}\mathbb{N}_{\infty}^{\textbf{g}[j]}$ is discrete and and if $\mathbf{I}\mathbb{N}_{\infty}^{\textbf{\emph{g}}[j]}$ be a proper dense subsemigroup of a Hausdorff semitopological semigroup $S$, then $S\setminus \mathbf{I}\mathbb{N}_{\infty}^{\textbf{\emph{g}}[j]}$ is a closed ideal of $S$, and moreover if $S$ is a topological inverse semigroup then $S\setminus \mathbf{I}\mathbb{N}_{\infty}^{\textbf{\emph{g}}[j]}$ is a topological group.
    This is a joint work with Pavlo Khylynskyi.

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October 23, 2020 O. Gutik
  • On the monoid of cofinite partial isometries of $\mathbb{N}$ with a bounded finite noise, II

    We extend results of the papers [Carl Eberhart and John Selden, On the Closure of the Bicyclic Semigroup, Transactions of the American Mathematical Society, Vol. 144 (Oct., 1969), pp. 115-126 ] and [M. O. Bertman and T. T. West, Conditionally Compact Bicyclic Semitopological Semigroups, Proceedings of the Royal Irish Academy. Section A: Mathematical and Physical Sciences Vol. 76 (1976), pp. 219-226] for the monoid $\mathbf{I}\mathbb{N}_{\infty}^{\textbf{g}[j]}$ of cofinite partial isometries of $\mathbb{N}$ with a bounded finite noise for any positive integer $j$. We describe the algebraic and topological structure of the closure of the monoid $\mathbf{I}\mathbb{N}_{\infty}^{\textbf{\emph{g}}[j]}$ in a locally compact topological inverse semigroup.
    This is a joint work with Pavlo Khylynskyi.

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December 16, 2020 S. Bardyla
(Kurt Gödel Research Center, University of Vienna)
  • Shift-invariant filters on the bicyclic monoid

    We will discuss different kinds of filters on the bicyclic monoid $\mathcal C$ and the corresponding topologies on $\mathcal C^0$. Our results provide a powerful method of constructing inverse semigroup topologies on $\mathcal C^0$. We describe the finest non-discrete inverse semigroup topology on $\mathcal C^0$. Also, we show that there exists a well-ordered chain of inverse semigroup topologies on $\mathcal C^0$ of length $\mathfrak b$.

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February 3, 2021 К. Максимик
  • Напівтопологічні інтерасоціативності біциклічного моноїда та біциклічні розширення

    За матеріалами кандидатської дисертації.

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February 4, 2021 М. Романський
  • Функтори і асимптотичні властивості метричних просторів

    За матеріалами кандидатської дисертації.

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О. Поливода (Шабат)
  • Нескінченновимірні многовиди, модельовані на прямих границях абсолютних екстензорів

    За матеріалами кандидатської дисертації.

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February 17, 2021 T. Mokrytskyi
  • The monoid of all order isomorphisms between principal filters of $\sigma(\mathbb{N}^K)$

    Let $K$ be any cardinality and $\mathcal{IP\!F}(\sigma(\mathbb{N}^K))$ be the semigroup of all order isomorphisms between principal filters of the set $\sigma(\mathbb{N}^K)$ with the product order. We study properties of the semigroup $\mathcal{IP\!F}(\sigma(\mathbb{N}^K))$.

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March 10, 2021 S. Bardyla
(Kurt Gödel Research Center, University of Vienna)
  • Completeness and related properties

    We provide a survey of recent results of Banakh and Bardyla concerning different completeness properties in topological semigroups, semilattices and pospaces.

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April 12, 2021 O. Gutik
  • On topologazations of the semigroup 𝓑𝓕ω

    We discuss whem the semigroup 𝓑𝓕ω admits only the discrete shift-continuous Hausdorff topology.
April 16, 2021 O. Mykytsey
(Ivano-Frankivsk)
  • Lattice-valued predicates on continuous semilattices

    The reporter discusses on the topic of her PhD thesis. The PhD thesis is devoted to lattice-valued monotonic predicates on continuous semilattices, which are natural generalizations of non-additive real-valued and lattice-valued measures.

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April 19, 2021 O. Gutik
  • On topological polycyclic extensions

    We disccus on topologizations of polycyclic extensions of monoids.
    This is a joint work with Pavlo Khylynskyi.

May 10, 2021 O. Gutik
  • On topological polycyclic extensions, II

    We disccus on topologizations of polycyclic extensions of monoids.
    This is a joint work with Pavlo Khylynskyi.

May 14, 2021 All participants
May 17, 2021 O. Gutik
  • On topological polycyclic extensions, III

    We disccus on topologizations of polycyclic extensions of monoids.
    This is a joint work with Pavlo Khylynskyi.

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May 19, 2021 O. Gutik
  • On topological polycyclic extensions, IV

    We disccus on topologizations of polycyclic extensions of monoids.
    This is a joint work with Pavlo Khylynskyi.

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June 7, 2021 O. Lysetska (Sobol)
  • On feebly compact topologies on the semigroup Ɓω1

    We study the Gutik-Mykhalenych semigroup Ɓω1 in the case when the family ℱ1 consists of the empty set and all singleton subsets of ω. We show that Ɓω1 is isomorphic to the subsemigroup of the Brandt ω-extension of the semilattice (ω,min) and describe all shift-continuous feebly compact T1-topologies on the semigroup Ɓω1.

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June 23, 2021 O. Gutik
  • On the semigroup $\boldsymbol{B}_{\omega}^{\mathcal{F}}$ which is generated by a family $\mathcal{F}$ of singletons of $\omega$

    We study the semigroup $\mathbf{B}_{\omega}^{\mathcal{F}}$ (which is introduced in the paper [Oleg Gutik, Mykola Mykhalenych, On some generalization of the bicyclic monoid, Visnyk of the Lviv University. Series Mechanics and Mathematics 90 (2020), 5-19]) in the case when the family $\mathcal{F}$ is generated by the family of singletons $\mathcal{F}$ of $\omega$. We describe the algebraic structure of the semigroup $\mathbf{B}_{\omega}^{\mathcal{F}}$, describe all shift-continuous feebly compact $T_1$-topologies on the semigroup $\mathbf{B}_{\omega}^{\mathcal{F}_1}$ and closure of $\mathbf{B}_{\omega}^{\mathcal{F}}$ in a (semi)topological semigroup.
    This is a joint work with Oleksandra Lysetska (Sobol)

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