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On topologization of the extended bicyclic semigroup
Gutik Oleg Volodymyrovych 1 , Zolotar Marharyta 2 , Lysetska Oleksandra 3
1 Department of Cybersecurity, Ivan Franko National University of Lviv, Lviv, 79000, Ukraine
2 Ivan Franko National University of Lviv, Ivan Franko National University of Lviv, 79000, Ukraine
3 Department of Mathematical Modeling of Socio-Economic Processes, Ivan Franko National University of Lviv, Lviv, 79000, Ukraine
Keywords: Extended bicyclic semigroup, bicyclic semigroup, topological semigroup, semitopological semigroup, $T_1$-space, Baire space, quasi-regular, discrete
Abstract

On the extended bicyclic semigroup $\mathscr{C}_\mathbb{Z}$ the following non-discrete $T_1$-topologies are constructed: $(i)$ a semigroup inverse topology; $(ii)$ a Baire left-continuous [right-continuous] topology; $(iii)$ a locally compact left-continuous [right-continuous] topology. We prove that, on $\mathscr{C}_\mathbb{Z}$ does not exist a countably compact left-continuous [right-continuous] $T_1$-topology. We give conditions under which a $T_1$-topology on $\mathscr{C}_\mathbb{Z}$ is discrete. In particular, $(i)$ a left-continuous [right-continuous] $T_1$-topology $\tau$ on $\mathscr{C}_\mathbb{Z}$ is discrete if and only if there exists a sequence $\{(i_n,j_n)\}_{n\in\mathbb{N}}$ of isolated points in $(\mathscr{C}_\mathbb{Z},\tau)$ such that the sequence $\{i_n\}_{n\in\mathbb{N}}$ $[\{j_n\}_{n\in\mathbb{N}}]$ is strictly increasing; $(ii)$ a shift-continuous $T_1$-topology $\tau$ on $\mathscr{C}_\mathbb{Z}$ is discrete if and only if the space $(\mathscr{C}_\mathbb{Z},\tau)$ contains an isolated point; $(iii)$ if the $T_1$-space of a topological inverse semigroup $(\mathscr{C}_\mathbb{Z},\tau)$ has a point $x$ such that $(\mathscr{C}_\mathbb{Z},\tau)$ is quasi-regular at $x$, then $\tau$ is discrete.

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Paper Received 1/19/2026
Paper Accepted 4/20/2026
Published Online 4/22/2026
Cite
ACS Style
Gutik, O.V.; Zolotar , M.; Lysetska, O. On topologization of the extended bicyclic semigroup. Bukovinian Mathematical Journal. 2026, 14 https://doi.org/https://doi.org/10.31861/bmj2026.01.12
AMA Style
Gutik OV, Zolotar M, Lysetska O. On topologization of the extended bicyclic semigroup. Bukovinian Mathematical Journal. 2026; 14(1). https://doi.org/https://doi.org/10.31861/bmj2026.01.12
Chicago/Turabian Style
Oleg Volodymyrovych Gutik, Marharyta Zolotar , Oleksandra Lysetska. 2026. "On topologization of the extended bicyclic semigroup". Bukovinian Mathematical Journal. 14 no. 1. https://doi.org/https://doi.org/10.31861/bmj2026.01.12
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