TY  - JOUR
AU  - Mirosaw, Adamek
AU  - Ali, Ali Hasan
AU  - Alina, Ramona Baias
AU  - Bessenyei, Mihály
AU  - Boros, Zoltán
AU  - Gilányi, Attila
AU  - Grünwald, Richárd
AU  - Gselmann, Eszter
AU  - Mehak, Iqbal
AU  - Kiss, Tibor
AU  - Kiss, Gergely
AU  - Menzer, Rayene
AU  - Nagy, Gergő
AU  - Páles, Zsolt
AU  - Székelyhidi, László
AU  - Szokol, Patrícia Ágnes
AU  - To, Lan Nhi
AU  - Tóth, Péter
AU  - Norbert, Tóth
TI  - The 59th International Symposium on Functional Equations Hotel Aurum, Hajdúszoboszló (Hungary), June 18-25, 2023
JF  - AEQUATIONES MATHEMATICAE
J2  - AEQUATIONES MATH
VL  - 97
PY  - 2023
IS  - 5-6
SP  - 1259
EP  - 1290
PG  - 32
SN  - 0001-9054
DO  - 10.1007/s00010-023-01007-3
UR  - https://m2.mtmt.hu/api/publication/34645176
ID  - 34645176
LA  - English
DB  - MTMT
ER  - 

TY  - JOUR
AU  - Székelyhidi, László
TI  - A GENERALIZATION OF THE HEISENBERG GROUP
JF  - Journal of the Iranian Mathematical Society
J2  - JIMS
VL  - 4
PY  - 2023
IS  - 2
SP  - 105
EP  - 119
PG  - 15
SN  - 2717-1612
DO  - 10.30504/JIMS.2023.396137.1113
UR  - https://m2.mtmt.hu/api/publication/34548656
ID  - 34548656
LA  - English
DB  - MTMT
ER  - 

TY  - JOUR
AU  - Fechner, Żywilla
AU  - Gselmann, Eszter
AU  - Székelyhidi, László
TI  - Moment functions of higher rank on some types of hypergroups
JF  - SEMIGROUP FORUM
J2  - SEMIGROUP FORUM
VL  - 107
PY  - 2023
IS  - 3
SP  - 624
EP  - 636
PG  - 13
SN  - 0037-1912
DO  - 10.1007/s00233-023-10401-x
UR  - https://m2.mtmt.hu/api/publication/34429967
ID  - 34429967
AB  - We consider moment functions of higher order. In our earlier paper, we have already investigated the moment functions of higher order on groups. The main purpose of this work is to prove characterization theorems for moment functions on the multivariate polynomial hypergroups and on the Sturm–Liouville hypergroups. In the first case, the moment generating functions of higher rank are partial derivatives (taken at zero) of the composition of generating polynomials of the hypergroup and functions whose coordinates are given by the formal power series. On Sturm–Liouville hypergroups the moment functions of higher rank are restrictions of even smooth functions that also satisfy certain boundary value problems. The second characterization of moment functions of higher rank on Sturm–Liouville hypergroups is given by means of an exponential family. In this case, the moment functions of higher rank are partial derivatives of an appropriately modified exponential family again taken at zero.
LA  - English
DB  - MTMT
ER  - 

TY  - JOUR
AU  - Abayomi, Epebinu
AU  - Ali, Ali Hasan
AU  - Bessenyei, Mihály
AU  - Boros, Zoltán
AU  - Chmielewska, Katarzyna
AU  - Chudziak, Jacek
AU  - Gát, György
AU  - Gilányi, Attila
AU  - Grünwald, Richárd
AU  - Gselmann, Eszter
AU  - Iqbal, Mehak
AU  - Kiss, Tibor
AU  - ükasik, Radosaw
AU  - Maslyuchenko, Oleksandr
AU  - Menzer, Rayene
AU  - Molnár, Gábor Marcell
AU  - Olbrys, Andrzej
AU  - Páles, Zsolt
AU  - Pénzes, Evelin
AU  - Pieszczek, Mateusz
AU  - Sablik, MacIej
AU  - Székelyhidi, László
AU  - Szostok, Tomasz
AU  - Tóth, Norbert
AU  - Tóth, Péter
AU  - Wójcik, Sebastian
AU  - Zürcher, Thomas
TI  - Report of Meeting: The Twenty-second Debrecen–Katowice Winter Seminar on Functional Equations and Inequalities Hajdúszoboszló (Hungary), February 1–4, 2023
JF  - ANNALES MATHEMATICAE SILESIANAE
J2  - ANN MATH SIL
VL  - 37
PY  - 2023
IS  - 2
SP  - 315
EP  - 334
PG  - 20
SN  - 0860-2107
DO  - 10.2478/amsil-2023-0006
UR  - https://m2.mtmt.hu/api/publication/34150382
ID  - 34150382
LA  - English
DB  - MTMT
ER  - 

TY  - JOUR
AU  - Fechner, Zywilla
AU  - Gselmann, Eszter
AU  - Székelyhidi, László
TI  - Generalized derivations and generalized exponential monomials on hypergroups
JF  - OPUSCULA MATHEMATICA
J2  - OPUSC MATHEMATICA
VL  - 43
PY  - 2023
IS  - 4
SP  - 493
EP  - 505
PG  - 13
SN  - 1232-9274
DO  - 10.7494/OpMath.2023.43.4.493
UR  - https://m2.mtmt.hu/api/publication/34087010
ID  - 34087010
AB  - In one of our former papers "Endomorphisms of the measure algebra of commutative hypergroups" we considered exponential monomials on hypergroups and higher order derivations of the corresponding measure algebra. Continuing with this, we are now looking for the connection between the generalized exponential polynomials of a commutative hypergroup and the higher order derivations of the corresponding measure algebra.
LA  - English
DB  - MTMT
ER  - 

TY  - JOUR
AU  - Székelyhidi, László
TI  - Finite dimensional varieties over the Heisenberg group
JF  - AEQUATIONES MATHEMATICAE
J2  - AEQUATIONES MATH
VL  - 97
PY  - 2023
IS  - 2
SP  - 377
EP  - 390
PG  - 14
SN  - 0001-9054
DO  - 10.1007/s00010-022-00911-4
UR  - https://m2.mtmt.hu/api/publication/33571640
ID  - 33571640
AB  - Spectral analysis and synthesis studies translation invariant function spaces, so-called varieties over topological groups. The basic building blocks are the finite dimensional varieties. In the commutative case finite dimensional varieties are spanned by exponential polynomials. In non-commutative situations no relevant results exist. In this paper we consider finite dimensional left translation invariant linear spaces of continuous complex valued functions over the Heisenberg group. Using basic knowledge about Lie algebra we describe all left varieties of this type. In particular, it turns out that those function spaces are spanned by exponential polynomials as well.
LA  - English
DB  - MTMT
ER  - 

TY  - JOUR
AU  - Burai, Pál
AU  - Bessenyei, Mihály
AU  - Boros, Zoltán
AU  - Chmieliński, Jacek
AU  - Chudziak, Jacek
AU  - Fazekas, Borbála Andrea
AU  - Ger, Roman
AU  - Gselmann, Eszter
AU  - Iqbal, Mehak
AU  - Łukasik, Radosław
AU  - Maslyuchenko, Oleksandr
AU  - Menzer, Rayene
AU  - Molnár, Gábor Marcell
AU  - Olbryś, Andrzej
AU  - Pasteczka, Paweł
AU  - Pénzes, Evelin
AU  - Sablik, Maciej
AU  - Sikorska, Justyna
AU  - Székelyhidi, László
AU  - Szokol, Patrícia Ágnes
AU  - Szostok, Tomasz
AU  - Tóth, Péter
AU  - Zürcher, Thomas
TI  - Report of Meeting: The Twenty-first Katowice–Debrecen Winter Seminar on Functional Equations and Inequalities Brenna (Poland), February 2–5, 2022
JF  - ANNALES MATHEMATICAE SILESIANAE
J2  - ANN MATH SIL
VL  - 36
PY  - 2022
IS  - 1
SP  - 92
EP  - 105
PG  - 14
SN  - 0860-2107
DO  - 10.2478/amsil-2022-0003
UR  - https://m2.mtmt.hu/api/publication/33574811
ID  - 33574811
LA  - English
DB  - MTMT
ER  - 

TY  - JOUR
AU  - Fechner, Zywilla
AU  - Gselmann, Eszter
AU  - Székelyhidi, László
TI  - Spectral synthesis via moment functions on hypergroups
JF  - FORUM MATHEMATICUM
J2  - FORUM MATH
VL  - 34
PY  - 2022
IS  - 5
SP  - 1187
EP  - 1197
PG  - 11
SN  - 0933-7741
DO  - 10.1515/forum-2021-0213
UR  - https://m2.mtmt.hu/api/publication/33014396
ID  - 33014396
AB  - In this paper, we continue the discussion about relations between exponential polynomials and generalized moment functions on a commutative hypergroup. We are interested in the following problem: is it true that every finite-dimensional variety is spanned by moment functions? Let m be an exponential on X. In our former paper, we have proved that if the linear space of all m-sine functions in the variety of an m-exponential monomial is (at most) one-dimensional, then this variety is spanned by moment functions generated by m. In this paper, we show that this may happen also in cases where the m-sine functions span a more than one-dimensional subspace in the variety. We recall the notion of a polynomial hypergroup in d variables, describe exponentials on it and give the characterization of the so-called m-sine functions. Next we show that the Fourier algebra of a polynomial hypergroup in d variables is the polynomial ring in d variables. Finally, using the Ehrenpreis-Palamodov Theorem, we show that every exponential polynomial on the polynomial hypergroup in d variables is a linear combination of moment functions contained in its variety.
LA  - English
DB  - MTMT
ER  - 

TY  - JOUR
AU  - Fechner, Zywilla
AU  - Gselmann, Eszter
AU  - Székelyhidi, László
TI  - Moment functions of higher rank on polynomial hypergroups
JF  - ADVANCES IN OPERATOR THEORY
J2  - ADV OPERAT THEORY
VL  - 7
PY  - 2022
IS  - 3
PG  - 9
SN  - 2538-225X
DO  - 10.1007/s43036-022-00204-2
UR  - https://m2.mtmt.hu/api/publication/32990639
ID  - 32990639
AB  - In this paper we consider generalized moment functions of higher order. These functions are closely related to the well-known functions of binomial type which have been investigated on various abstract structures. In our former paper we investigated the properties of generalized moment functions of higher order on commutative groups. In particular, we proved the characterization of generalized moment functions on a commutative group as the product of an exponential and composition of multivariate Bell polynomial and a sequence additive functions. In the present paper we continue the study of generalized moment function sequences of higher order in the more abstract setting, namely we consider functions defined on a hypergroup. We characterize these functions on the polynomial hypergroup in one variable by means of partial derivatives of a composition of polynomials generating the polynomial hypergroup and an analytic function. As an example, we give an explicit formula for moment generating functions of rank at most two on the Tchebyshev hypergroup.
LA  - English
DB  - MTMT
ER  - 

TY  - JOUR
AU  - Székelyhidi, László
TI  - Spectral analysis and synthesis on an infinite hypergroup join
JF  - PUBLICATIONES MATHEMATICAE DEBRECEN
J2  - PUBL MATH DEBRECEN
VL  - 99
PY  - 2021
IS  - 3-4
SP  - 261
EP  - 273
PG  - 13
SN  - 0033-3883
DO  - 10.5486/PMD.2021.8709
UR  - https://m2.mtmt.hu/api/publication/32497975
ID  - 32497975
LA  - English
DB  - MTMT
ER  -