| 12. 5. 2022 |
Ján Haluška – An ensemble of 6 ordered vector algebras, epimorphic to 6 generalized complex numbers
is a generalization of 12-TET |
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Abstract:
A $12$-dimensional linearly ordered vector algebra $\mathscr{W}_{12}$ over $\mathbb{R}$ is inspired with 12-Tone Equal Temperament Tuning system (12-TET) which is generally known in mathematical acoustics.
In the paper introduced definition of multiplication $\otimes$ is based on a chain of 85 vectors of the Pythagorean approximation cycle and the notion of octave equivalence. From the operation $\otimes$, it is derived an operation $\oplus$ (operation of transposition, shift of vectors). The operation $\otimes$ is associative, commutative and distributive with respect to $\oplus$. In the paper, there are considered first 6 sub-algebras of $\mathscr{W}_{12}$; $\mathscr{W}_{1} \subset \mathscr{W}_{2} \subset \mathscr{W}_{3} \subset \mathscr{W}_{6} \subset \mathscr{W}_{12}$, $\mathscr{W}_{2} \subset \mathscr{W}_{4} \subset \mathscr{W}_{12}$. We can compute all possible invertible vectors (if they exist) in all ordered sub-algebras of $\mathscr{W}_{12}$.
We describe only some interconnections among various substructures of $\mathscr{W}_{12}$, neither its numerous non-mathematical applications.
According to results of the paper, we can claim that each tonal European musical composition is algebraically isomorphic with a sequence of lineals (=chords) of vectors (=tones) in $\mathscr{W}_{12}$ in time.
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| 26. 5. 2022 |
Peter Eliaš – On tensor product |
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Abstract:
We compare construction of tensor product in the category of vector space, where morphisms are linear maps, and the category
of complete lattices, where morphisms are join-preserving maps.
Tensor product of vector spaces $V$, $W$ is a vector space $T=V\otimes W$, together with a map $\otimes\colon V\times W\to T$,
possessing a universal property with respect to all bilinear maps from the cartesian product $V\times W$ into arbitrary vector space $U$.
Tensor product of complete lattices $K$, $L$ (in the category where morphisms are join-preserving maps)
is the lattice $G$ of all Galois connections between $K$, $L$, together with an appropriate map $\varphi\colon K\times L\to G$.
This map possess a universal property with respect to all maps defined of $K\times L$ that preserve joins in each variable separately.
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| 9. 6. 2022 |
Michal Hospodár – Operations on subregular languages and nondeterministic state complexity |
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Abstract:
We study the nondeterministic state complexity of basic regular
operations on subregular language families. In particular, we focus
on the classes of combinational, finitely generated left ideal, group,
star, comet, two-sided comet, ordered, and power-separating languages,
and consider the operations of intersection, union, concatenation, power,
Kleene star, reversal, and complementation. We get the exact complexity
in all cases, except for complementation of group languages where we
only have an exponential lower bound. The complexity of all operations
on combinational languages is given by a constant function, except for
the $k$-th power where it is $k+1$. For all considered operations, the known
upper bounds for left ideals are met by finitely generated left ideal languages.
The nondeterministic state complexity of the $k$-th power, star, and
reversal on star languages is $n$. In all the remaining cases, the nondeterministic
state complexity of all considered operations is the same as in
the regular case, although sometimes we need to use a larger alphabet
to describe the corresponding witnesses.
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| 23. 6. 2022 |
Emília Halušková – On discrete properties of several real functions |
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Abstract:
Monounary algebras are the most simple algebraic structures. They are defined as a pair $(A, f)$, where $A$ is a nonempty set and $f$ is a mapping from $A$ to $A$.
They are represented by oriented graphs in which exactly one edge emerges from each vertex. They are interdisciplinary in nature. We will illustrate this
in Sharkovsky's theorem (1964) from the theory of dynamical systems
and Łojasiewicz's theorem (1951)
from the theory of iterative roots.
Next, we present the classification of monounary algebras defined on an interval of real numbers with a continuous strictly monotone function
according to decompositions into connected components, more precisely according to the types of non-isomorphic connected components that occur in these algebras.
Monounary algebras defined intervals of real number with a continuous strictly monotone operation contain at most 4 mutually nonisomorphic components.
If the interval is closed and bounded, then 8 combinations of these components are possible. For other intervals, 10 combinations are possible.
The bijectivity of the function, the set of fixed points of the function or its second iteration and the bounding of the function on the maximal subset of the domain
that does not contain the fixed points of the function play a role in the criteria.
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| 8. 9. 2022 |
Małgorzata Jastrzębska (UPH Siedlce) – Lattices in associative rings |
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Abstract:
The aim of the talk is to present the methods of lattice theory in studying the properties of associative rings.
The lattices of ideals, the lattices of one-sided ideals and the lattices of one-sided annihilators will be discussed.
I will present the relationships between these lattices and their selected properties. I will also present a few theorems
characterizing the properties of rings with the help of mentioned lattices.
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| 22. 9. 2022 |
Viktor Olejár – Selected topics in quantum finite automata |
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Abstract:
Quantum finite automata literature offers an alternative mathematical
model for studying quantum systems with finite memory. Many different
models have been proposed with varying computational powers.
Moore-Crutchfield quantum finite automaton (MCQFA) is one of the
earliest proposed models which is obtained by replacing the transition
matrices of the classical finite automata by unitary operators. Despite
the fact that they are weaker than their classical counterparts in terms
of their language recognition power, for certain tasks MCQFAs have been
shown to be more succinct. We explore two such examples: the language
$\mathtt{MOD}_{p}=\{a^{j} \mid j \equiv 0 \mod p\}$ where $p$ is a prime
number, and the promise problem $\mathtt{EVENODD}^k =
(\mathtt{EVENODD}^k_{\text{yes}}, \mathtt{EVENODD}^k_{\text{no}})$ for a
fixed positive integer $k$. We also review some past activities
concerning research and education in related quantum computing fields:
relevant organizations,
workshops (first a
second),
summer schools, etc.
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| 6. 10. 2022 |
Galina Jirásková – Multiple concatenation and state complexity |
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Abstract:
We describe witnesses for the concatenation of $k$ languages
over an alphabet of $k + 1$ symbols with a significantly simpler proof
then that from the literature. Then we use slightly modified Maslov’s
automata to get witnesses over a $k$-letter alphabet which solves an open
problem stated by Caron et al. [2018, Fund. Inform. 160, 255–279]. We
prove that for $k = 3$, the ternary alphabet is optimal. We also obtain
lower bounds $n_1 - 1 + (1/2^{2k-2})2^{n_2+···+n_k}$
and $(1/2^{2k-2})n_1 2^{n_2+···+n_k}$ in
the binary and ternary case, respectively. Finally, we show that an upper
bound for unary cyclic languages is $n_1n_k/d + n_1 + ··· + n_k - k +1+ d$
where $n_1 \le···\le n_k$ and $d = \gcd(n_1,...,n_k)$.
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| 20. 10. 2022 |
Ján Brajerčík (University of Prešov) – Problems of global variational geometry |
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Abstract:
In the talk we introduce basic concepts concerning global variational geometry
such as smooth manifold, fibered manifold, jet, Lagrangian, Euler-Lagrange equation.
Examples of problems solved by methods of global variational geometry are discussed.
Reference: The Lepage Research Institute
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| 3. 11. 2022 |
Irena Jadlovská – Canonical representation of disconjugate operators |
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Abstract:
We recall Polya and Trench’s classical results on factorizations of
disconjugate linear operators. The usefulness of Trench’s canonical
representation in the study of binomial differential equations is
demonstrated. Several recently obtained related results are discussed,
including explicit formulas for canonical representation of n-th order
noncanonical disconjugate operators, general relations between
solutions of canonical and noncanonical two-term functional
differential equations, and extensions of the canonical classification
scheme of possible nonoscillatory solutions from linear to
differential equations with power-type nonlinearity or dynamic
equations on time scales.
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| 24. 11. 2022 |
Jozef Pócs – Join dense subset of aggregation functions |
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Abstract:
Aggregation functions defined on a bounded lattice form a bounded lattice with respect to the point-wise operations of join and meet.
We describe a general way of finding join dense subsets in lattices of functions and also discuss the minimality of these sets.
The obtained results are applied to the lattice of aggregation functions and to the lattice of idempotent aggregation functions.
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