@article{MTMT:34751048,
	title = {Reduction of positive self-adjoint extensions},
	url = {https://m2.mtmt.hu/api/publication/34751048},
	author = {Tarcsay, Zsigmond and Sebestyén, Zoltán},
	doi = {10.7494/OpMath.2024.44.3.425},
	journal-iso = {OPUSC MATHEMATICA},
	journal = {OPUSCULA MATHEMATICA},
	volume = {44},
	unique-id = {34751048},
	issn = {1232-9274},
	year = {2024},
	pages = {425-438},
	orcid-numbers = {Tarcsay, Zsigmond/0000-0001-8102-5055}
}

@article{MTMT:34082427,
	title = {Oscillation conditions for difference equations with several variable delays},
	url = {https://m2.mtmt.hu/api/publication/34082427},
	author = {El-Matary, Bassant M. and El-Morshedy, Hassan A. and Benekas, Vasileios and Stavroulakis, Ioannis P.},
	doi = {10.7494/OpMath.2023.43.6.789},
	journal-iso = {OPUSC MATHEMATICA},
	journal = {OPUSCULA MATHEMATICA},
	volume = {43},
	unique-id = {34082427},
	issn = {1232-9274},
	abstract = {A technique is developed to establish a new oscillation criterion for a first-order linear difference equation with several delays and non-negative coefficients. Our result improves recent oscillation criteria and covers the cases of monotone and non-monotone delays. Moreover, the paper is concluded with an illustrative example to show the applicability and strength of our result.},
	year = {2023},
	pages = {789-801},
	orcid-numbers = {El-Matary, Bassant M./0000-0003-4525-156X; El-Morshedy, Hassan A./0000-0003-2571-1215; Benekas, Vasileios/0000-0001-9693-1499; Stavroulakis, Ioannis P./0000-0002-4810-0540}
}

@article{MTMT:34349785,
	title = {SOLUTIONS FOR A NONHOMOGENEOUS p&q-LAPLACIAN PROBLEM VIA VARIATIONAL METHODS AND SUB-SUPERSOLUTION TECHNIQUE},
	url = {https://m2.mtmt.hu/api/publication/34349785},
	author = {Tavares, Leandro S. and Sousa, J. Vanterler C.},
	doi = {10.7494/OpMath.2023.43.4.603},
	journal-iso = {OPUSC MATHEMATICA},
	journal = {OPUSCULA MATHEMATICA},
	volume = {43},
	unique-id = {34349785},
	issn = {1232-9274},
	abstract = {In this paper it is obtained, through variational methods and sub-supersolution arguments, existence and multiplicity of solutions for a nonhomogeneous problem which arise in several branches of science such as chemical reactions, biophysics and plasma physics. Under a general hypothesis it is proved an existence result and multiple solutions are obtained by considering an additional natural condition.},
	keywords = {EXISTENCE; Multiplicity; nonhomogeneous operator; sub-supersolutions; p&q-Laplacian operator},
	year = {2023},
	pages = {603-613}
}

@article{MTMT:34087010,
	title = {Generalized derivations and generalized exponential monomials on hypergroups},
	url = {https://m2.mtmt.hu/api/publication/34087010},
	author = {Fechner, Zywilla and Gselmann, Eszter and Székelyhidi, László},
	doi = {10.7494/OpMath.2023.43.4.493},
	journal-iso = {OPUSC MATHEMATICA},
	journal = {OPUSCULA MATHEMATICA},
	volume = {43},
	unique-id = {34087010},
	issn = {1232-9274},
	abstract = {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.},
	keywords = {DERIVATION; Hypergroup; Moment function; exponential monomials; exponential polynomial; moment sequence; Derivation of higher order},
	year = {2023},
	pages = {493-505},
	orcid-numbers = {Gselmann, Eszter/0000-0002-1708-2570; Székelyhidi, László/0000-0001-8078-6426}
}

@article{MTMT:34015297,
	title = {Periodic, nonperiodic, and chaotic solutions for a class of difference equations with negative feedback},
	url = {https://m2.mtmt.hu/api/publication/34015297},
	author = {Kennedy, Benjamin B.},
	doi = {10.7494/OpMath.2023.43.4.507},
	journal-iso = {OPUSC MATHEMATICA},
	journal = {OPUSCULA MATHEMATICA},
	volume = {43},
	unique-id = {34015297},
	issn = {1232-9274},
	abstract = {We study the scalar difference equation \[x(k+1) = x(k) + \frac{f(x(k-N))}{N},\] where \(f\) is nonincreasing with negative feedback. This equation is a discretization of the well-studied differential delay equation \[x'(t) = f(x(t-1)).\] We examine explicit families of such equations for which we can find, for infinitely many values of $ and appropriate parameter values, various dynamical behaviors including periodic solutions with large numbers of sign changes per minimal period, solutions that do not converge to periodic solutions, and chaos. We contrast these behaviors with the dynamics of the limiting differential equation. Our primary tool is the analysis of return maps for the difference equations that are conjugate to continuous self-maps of the circle.},
	year = {2023},
	pages = {507-546}
}

@article{MTMT:33943060,
	title = {SINGULAR ELLIPTIC PROBLEMS WITH DIRICHLET OR MIXED DIRICHLET-NEUMANN NON-HOMOGENEOUS BOUNDARY CONDITIONS},
	url = {https://m2.mtmt.hu/api/publication/33943060},
	author = {Godoy, Tomas},
	doi = {10.7494/OpMath.2023.43.1.19},
	journal-iso = {OPUSC MATHEMATICA},
	journal = {OPUSCULA MATHEMATICA},
	volume = {43},
	unique-id = {33943060},
	issn = {1232-9274},
	abstract = {Let Omega be a C-2 bounded domain in R-n such that partial derivative Omega = Gamma(1) boolean OR Gamma(2), where Gamma(1) and Gamma(2) are disjoint closed subsets of partial derivative Omega, and consider the problem -Delta u = g(. , u) in Omega, u = tau on Gamma(1), partial derivative u/partial derivative nu = eta on Gamma(2), where 0 <= t is an element of W-1/2,W-2(Gamma(1)), eta is an element of (H-0,Gamma 1(1), (Omega))', and g : Omega x(0,infinity) -> R is a nonnegative Caratheodory function. Under suitable assumptions on g and eta we prove the existence and uniqueness of a positive weak solution of this problem. Our assumptions allow g to be singular at s = 0 and also at x is an element of S for some suitable subsets S subset of (Omega) over bar. The Dirichlet problem -Delta u = g(., u) in Omega, u = sigma on partial derivative Omega is also studied in the case when 0 <= sigma is an element of W-1/2,W-2 (Omega).},
	keywords = {mixed boundary conditions; Weak solutions; singular elliptic problems},
	year = {2023},
	pages = {19-46}
}

@article{MTMT:33840469,
	title = {STRONG CONSISTENCY OF THE LOCAL LINEAR RELATIVE REGRESSION ESTIMATOR FOR CENSORED DATA},
	url = {https://m2.mtmt.hu/api/publication/33840469},
	author = {Bouhadjera, Feriel and Said, Elias Ould},
	doi = {10.7494/OpMath.2022.42.6.805},
	journal-iso = {OPUSC MATHEMATICA},
	journal = {OPUSCULA MATHEMATICA},
	volume = {42},
	unique-id = {33840469},
	issn = {1232-9274},
	abstract = {In this paper, we combine the local linear approach to the relative error regression estimation method to build a new estimator of the regression operator when the response variable is subject to random right censoring. We establish the uniform almost sure consistency with rate over a compact set of the proposed estimator. Numerical studies, firstly on simulated data, then on a real data set concerning the death times of kidney transplant patients, were conducted. These practical studies clearly show the superiority of the new estimator compared to competitive estimators.},
	keywords = {censored data; Regression function; Relative error; local linear approach; uniform almost sure convergence},
	year = {2022},
	pages = {805-832}
}

@article{MTMT:34585306,
	title = {STABILITY SWITCHES IN A LINEAR DIFFERENTIAL EQUATION WITH TWO DELAYS},
	url = {https://m2.mtmt.hu/api/publication/34585306},
	author = {Hata, Yuki and Matsunaga, Hideaki},
	doi = {10.7494/OpMath.2022.42.5.673},
	journal-iso = {OPUSC MATHEMATICA},
	journal = {OPUSCULA MATHEMATICA},
	volume = {42},
	unique-id = {34585306},
	issn = {1232-9274},
	abstract = {This paper is devoted to the study of the effect of delays on the asymptotic stability of a linear differential equation with two delays x'(t) = -ax(t) - bx(t - tau) - cx(t - 2 tau), t >= 0, where a, b, and c are real numbers and tau > 0. We establish some explicit conditions for the zero solution of the equation to be asymptotically stable. As a corollary, it is shown that the zero solution becomes unstable eventually after undergoing stability switches finite times when tau increases only if c - a < 0 and root-8c(c - a) < vertical bar b vertical bar < a+ c. The explicit stability dependence on the changing t is also described.},
	keywords = {Delay differential equations; Stability switches; Mathematics, Applied},
	year = {2022},
	pages = {673-690},
	orcid-numbers = {Matsunaga, Hideaki/0000-0001-5805-2303}
}

@article{MTMT:33450866,
	title = {PROPERTIES OF EVEN ORDER LINEAR FUNCTIONAL DIFFERENTIAL EQUATIONS WITH DEVIATING ARGUMENTS OF MIXED TYPE},
	url = {https://m2.mtmt.hu/api/publication/33450866},
	author = {Dzurina, Jozef},
	doi = {10.7494/OpMath.2022.42.5.659},
	journal-iso = {OPUSC MATHEMATICA},
	journal = {OPUSCULA MATHEMATICA},
	volume = {42},
	unique-id = {33450866},
	issn = {1232-9274},
	abstract = {This paper is concerned with oscillatory behavior of linear functional differential equations of the typey((n))(t) = p(t)y(tau(t))with mixed deviating arguments which means that its both delayed and advanced parts are unbounded subset of (0, infinity). Our attention is oriented to the Euler type of equation, i.e. when p(t) similar to a/t(n).},
	keywords = {oscillation; higher order differential equations; mixed argument; monotonic properties},
	year = {2022},
	pages = {659-671}
}

@article{MTMT:33450868,
	title = {OSCILLATION OF EVEN ORDER LINEAR FUNCTIONAL DIFFERENTIAL EQUATIONS WITH MIXED DEVIATING ARGUMENTS},
	url = {https://m2.mtmt.hu/api/publication/33450868},
	author = {Baculikova, Blanka},
	doi = {10.7494/OpMath.2022.42.4.549},
	journal-iso = {OPUSC MATHEMATICA},
	journal = {OPUSCULA MATHEMATICA},
	volume = {42},
	unique-id = {33450868},
	issn = {1232-9274},
	abstract = {In the paper, we study oscillation and asymptotic properties for even order linear functional differential equationsy((n))(t) = p(t)y(tau(t))with mixed deviating arguments, i.e. when both delayed and advanced parts of tau(t) are significant. The presented results essentially improve existing ones.},
	keywords = {oscillation; higher order differential equations; mixed argument; monotonic properties},
	year = {2022},
	pages = {549-560}
}