Aneta Sikorska-Nowak

Prof. Dr. Aneta Sikorska-Nowak

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Research Focus & Metrics

Academic Career Length

25Years (2002-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 September 2012 in Demonstratio Mathematica
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MCMieczysław Cichoń
Mieczysław Cichoń
IKIreneusz Kubiaczyk
Ireneusz Kubiaczyk
ASAneta Sikorska-Nowak
Aneta Sikorska-Nowak
AYAhmet Yantir
Ahmet Yantir
In this paper we obtain the existence of solutions and Carathéodory type solutions of the dynamic Cauchy problem in Banach spaces for functions defined on time scales x Δ ( t ) = f ( t , x ( t ) ) , x ( 0 ) = x 0 , t ∈ I a , $$\matrix{{x^\Delta (t) = f(t,x(t)),} \hfill & {} \hfill \cr {x(0) = x_0 ,} \hfill & {t \in I_a ,} \hfill } $$ where f is continuous or f satisfies Carathéodory conditions and some conditions expressed in terms of measures of noncompactness. The Mönch fixed point theorem is used to prove the main result, which extends these obtained for real valued functions.

1 December 2008 in Bulletin of the Australian Mathematical Society
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RARavi P. Agarwal
Ravi P. Agarwal
Donal O'ReganDonal O'Regan
Donal O'Regan
ASAneta Sikorska-Nowak
Aneta Sikorska-Nowak
In this paper, we first prove an existence theorem for the integrodifferential equation (*) wheref,k,xare functions with values in a Banach spaceEand the integral is taken in the sense of Henstock–Kurzweil–Pettis. In the second part of the paper we show that the setSof all solutions of the problem (*) is compact and connected in (C(Id,E),ω), where $I_{d} \subset I_{a} $ .

1 January 2004 in Annales Polonici Mathematici
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ASAneta Sikorska-Nowak
Aneta Sikorska-Nowak
We prove some existence theorems for nonlinear integral equations of the Urysohn type $x(t)=\varphi (t)+\lambda \int _0^a f(t,s,x(s))\, ds$ and Volterra type $x(t)=\varphi (t)+\int _0^tf(t,s,x(s))\, ds$, $t\in I_a=[0,a]$, where $f$ and $\varphi $ are func

1 February 2023 in Mathematica Slovaca
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GNGrzegorz Nowak
Grzegorz Nowak
SSSamir H. Saker
Samir H. Saker
ASAneta Sikorska-Nowak
Aneta Sikorska-Nowak
In this paper, by using Sadovskii’s fixed point theorem and the properties of the measure of noncompactness, we establish some sufficient conditions for the asymptotic stability results of nonlinear neutral integro-differential equations with variable delays. The results presented in this paper improve and generalize some results in the literature. An example is considered to illustrate our main results.

18 April 2023 in Electronic Journal of Differential Equations
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ASAneta Sikorska-Nowak
Aneta Sikorska-Nowak
In this article we prove the existence of solutions to the integrodifferential equation of mixed type \begin{gather*}x^\Delta (t)=f \Big( t,x(t), \int_0^t k_1 (t,s)g(s,x(s)) \Delta s, \int_0^a k_2(t,s)h(s,x(s)) \Delta s \Big),\cr x(0)=x_0, \quad x_0 \in E,\; t \in I_a=[0,a] \cap \mathbb{T},\; a>0, \end{gather*} where \(\mathbb{T}\) denotes a time scale (nonempty closed subset of real numbers \(\mathbb{R}\)), \(I_a\) is a time scale interval. In the first part of this paper functions \(f,g,h\) are Caratheodory functions with values in a Banach space E and integrals are taken in the sense of Henstock-Kurzweil delta integrals, which generalizes the Henstock-Kurzweil integrals. In the second part f, g, h, x are weakly-weakly sequentially continuous functions and integrals are taken in the sense of Henstock-Kurzweil-Pettis delta integrals. Additionally, functions f, g, h satisfy some boundary conditions and conditions expressed in terms of measures of noncompactness.

1 February 2009 in Journal of Numerical Analysis and Approximation Theory
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GNGrzegorz Nowak
Grzegorz Nowak
ASAneta Sikorska-Nowak
Aneta Sikorska-Nowak
In this paper we consider the modified Szasz-Mirakyan-Kantorovich operators for functions \(f\) integrable in the sense of Denjoy-Perron. Moreover, we estimate the rate of pointwise convergence of \(M_nf(x)\) at the Lebesgue-Denjoy points \(x\) of \(f\) .