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September 8, 2011
| O.Ravsky
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- Наївна спроба отримати алгебраїчну характеризацію
напівгруп ендоморфізмів класу F моноунарних алгебр: структура
напівгруп ендоморфізмів моноунарних алгебр класу F (початок)
- The reporter will be discussed on the topics which are annonced in
the title of report.
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September 15, 2011,
September 22, 2011,
September 29, 2011
| O. Ravsky
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- Моноунарні алгебри: хто вони?
- Будуть наведені різноманітні приклади моноунарних алгебр з
різних галузей математики, зокрема у Проблемі 3n+1, конвеєвскій грі "Житття" та фракталах.
По останнім двом прикладам планується КІНО
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October 6, 2011,
October 13, 2011,
October 20, 2011
| O. Ravsky
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- The product of a nonempty family of pseudocompact
paratopological groups is pseudocompact
- Will be proved the statement which is announced in the title.
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Februaary 15, 2012
| O. Ravsky
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A specific example of a locally compact cancellative semigroup S which cannot be a subsemigroup
of a paratopological group.
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Answering a next question of I. Guran we construct a locally compact Polish cancellative
abelian semigroup S such that all shifts on S are quasi-open (that is, int (a+U) is non-empty for
each element a\in S and each nonempty open subset U of S), but S cannot be a subsemigroup of a
paratopological group.
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Februaary 22, 2012
| O. Ravsky
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Each discrete subgroup of $S_\omega(X)$ is finite.
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Let $X$ be an infinite set and $S_\omega(X)$ be the group of all bijections of $X$ with finite supporter,
endowed with the topology of the pointwise convergence. Inspired by the talk with I. Guran, we show that
each discrete subgroup of $S_\omega(X)$ is finite.
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Februaary 29, 2012,
March 7, 2012,
March 14, 2012,
March 21, 2012,
March 28, 2012,
April 4, 2012
| O.
Gutik
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On monoids of injective partial cofinite selfmaps.
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We discuss on the semigroup $\mathscr{I}^{\mathrm{cf}}_\lambda$ of
injective partial cofinite selfmaps of infinite cardinal $\lambda$.
We show that $\mathscr{I}^{\mathrm{cf}}_\lambda$ is a bisimple
inverse semigroup and for every non-empty chain $L$ in
$E(\mathscr{I}^{\mathrm{cf}}_\lambda)$ there exists an inverse
subsemigroup $S$ of $\mathscr{I}^{\mathrm{cf}}_\lambda$ such that
$S$ is isomorphic to the bicyclic semigroup and $L\subseteq E(S)$,
we describe the Green relations on
$\mathscr{I}^{\mathrm{cf}}_\lambda$ and we prove that every
non-trivial congruence on $\mathscr{I}^{\mathrm{cf}}_\lambda$ is a
group congruence. We also prove that every Hausdorff locally compact
topology $\tau$ on $\mathscr{I}^{\mathrm{cf}}_\lambda$ such that
$(\mathscr{I}^{\mathrm{cf}}_\lambda,\tau)$ is a semitopological
semigroup, is discrete and we describe the closure of the discrete
semigroup $\mathscr{I}^{\mathrm{cf}}_\lambda$ in a topological
semigroup. Finally, we show that the (discrete) semigroup
$\mathscr{I}^{\mathrm{cf}}_\lambda$ cannot embed into a compact-like
topological semigroup for any infinite cardinal $\lambda$, and we
construct two non-discrete Hausdorff topologies which turn
$\mathscr{I}^{\mathrm{cf}}_\lambda$ into a topological inverse
semigroup.
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Agust 6, 2012,
Agust 8, 2012
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Kateryna Pavlyk (University of Tartu, Estonia)
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Pseudocompact topological Brandt $\lambda^0$-extensions of semitopological semigroups
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We introduce pseudocompact (resp., countably compact, sequentially compact, compact) topological Brandt
$\lambda^0$-extensions of pseudocompact (resp., countably compact, sequentially compact, compact) semitopological
semigroups in the class of semitopological semigroups and establish the structure of such extensions.
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