Wyniki wyszukiwania - Biblioteka Nauki

1

On positive definite and stationary sequences with respect to polynomial hypergroups

100%

Lasser R.

Journal of Applied Analysis

|

2011

|

tom Vol. 17, nr 2

207-230

EN

We study bounded positive definite double sequences which are stationary with respect to a polynomial hypergroup structure generated by (Rn(t)) ∈nNo. Connected with bounded positive definite and Rn-stationary double sequences is an Rn-stationary sequence of elements in a Hilbert space. We derive an ergodic theorem for such Rn-stationary sequences and we give a complete characterization of the space of multipliers defined by such an Rn-stationary sequence. Further we give examples of bounded positive definite double sequences.

2

Ergodic theorems for Markov chains represented by iterated function systems

84%

Stenflo O.

Bulletin of the Polish Academy of Sciences. Mathematics

|

2001

|

tom Vol. 49, no 1

27--43

EN

We consider Markov chains represented in the form Xn+1 = f (Xn, In), where {In} is a sequence of independent, identically distributed (i.i.d.) random variables, and where f is a measurable function. Any Markov chain {Xn} on a Polish state space may be represented in this form i.e. can be considered as arising from an iterated function system (IFS). A distributional ergodic theorem, including rates of convergence in the Kantorovich distance is proved for Markov chains under the condition that an IFS representation is "stochastically contractive" and "stochastically bounded". We apply this result to prove our main theorem giving upper bounds for distances between invariant probability measures for iterated function systems. We also give some examples indicating how ergodic theorems for Markov chains may be proved by finding contractive IFS representations. These ideas are applied to some Markov chains arising from iterated function systems with place dependent probabilities.

3

Projekcja odwrócona (inverse projection) jako narzędzie wspomagające poznanie przeszłości demograficznej

84%

Bród D. , Rychwał P. , Strzelecki P.

Przeszłość Demograficzna Polski

|

2016

|

tom 38

|

nr 38, 2016, nr 4

89-118

PL

Celem artykułu jest zaprezentowanie cech sprawiających, że metoda projekcji odwróconej (inverse projection) stanowi dogodne narzędzie wnioskowania o zmianach struktury wieku ludności i parametrów demograficznych w badaniach przeszłości demograficznej. W porównaniu z najczęściej wykorzystywaną do tej pory metodą rekonstrukcji rodzin, metoda projekcji odwróconej wymaga mniejszego zakresu danych wejściowych (zagregowane liczby urodzeń i zgonów w kolejnych okresach) oraz stwarza możliwości szerokiego wykorzystywania demograficznych narzędzi w postaci modelowych tablic trwania życia i struktury wieku ludności do tworzenia modeli spójnych z dostępnymi danymi historycznymi. W artykule pokazano ponadto, że dzięki własnościom ergodycznym procesów demograficznych oraz wbudowanemu mechanizmowi autokorekty, niezależnie od przyjmowanych początkowo założeń eksperckich, metoda projekcji odwróconej prowadzi po pewnym czasie do zbliżonych do siebie wyników. Kluczowe dla wiarygodności wyników są jednak informacje źródłowe o ruchu naturalnym ludności

EN

The aim of the article is to present the features revealing that the inverse projection method is a useful tool of inferring the changes in the age structure of the population and demographic parameters while researching the demographic past. Compared to the so far most frequent method of reconstructing families, the inverse projection method requires fewer initial data (aggregated number of births and deaths in the subsequent periods) and creates possibility of how to make the most of demographic tools such as model tables of life duration and the age structure of the population in order to create coherent models with accessible historical data. In addition, the article proves that thanks to the ergodic properties of demographic processes and the built-in mechanism of self-correction, irrespective of the initial expert assumptions, the inverse projection method finally leads to similar results. The source information on the natural movement of the population is of key importance for the credibility of the results.

4

Ergodic theory approach to chaos: remarks and computational aspects

84%

Mitkowski P. J. , Mitkowski W.

International Journal of Applied Mathematics and Computer Science

|

2012

|

tom Vol. 22, no. 2

259-267

EN

We discuss basic notions of the ergodic theory approach to chaos. Based on simple examples we show some characteristic features of ergodic and mixing behaviour. Then we investigate an infinite dimensional model (delay differential equation) of erythropoiesis (red blood cell production process) formulated by Lasota. We show its computational analysis on the previously presented theory and examples. Our calculations suggest that the infinite dimensional model considered possesses an attractor of a nonsimple structure, supporting an invariant mixing measure. This observation verifies Lasota's conjecture concerning nontrivial ergodic properties of the model.

5

Ergodic and fixed point theorems for sequences and nonlinear mappings in a Hilbert space

67%

Rouhani B. D.

Demonstratio Mathematica

|

2018

|

tom Vol. 51, nr 1

27--36

EN

In this paper, we introduce the notion of 2-generalized hybrid sequences, extending the notion of nonexpansive and hybrid sequences introduced and studied in our previous work [Djafari Rouhani B., Ergodic theorems for nonexpansive sequences in Hilbert spaces and related problems, Ph.D. thesis, Yale University, 1981; and other published in J. Math. Anal. Appl., 1990, 2002, and 2014; Nonlinear Anal., 1997, 2002, and 2004], and prove ergodic and convergence theorems for such sequences in a Hilbert space H. Subsequently, we apply our results to prove new fixed point theorems for 2-generalized hybrid mappings, first introduced in [Maruyama T., Takahashi W., Yao M., Fixed point and mean ergodic theorems for new nonlinear mappings in Hilbert spaces, J. Nonlinear Convex Anal., 2011, 12, 185-197] and further studied in [Lin L.-J., Takahashi W., Attractive point theorems and ergodic theorems for nonlinear mappings in Hilbert spaces, Taiwanese J. Math., 2012, 16, 1763-1779], defined on arbitrary nonempty subsets of H.