We prove some versions of abstract Korovkin-type theorems in modular function spaces, with respect to filter convergence for linear positive operators, by considering several kinds of test functions. We give some results with respect to an axiomatic convergence, including almost convergence. An extension to non positive operators is also studied. Finally, we give some examples and applications to moment and bivariate Kantorovich-type operators, showing that our results are proper extensions of the corresponding classical ones.
@article{bwmeta1.element.doi-10_2478_s11533-013-0288-7, author = {Carlo Bardaro and Antonio Boccuto and Xenofon Dimitriou and Ilaria Mantellini}, title = {Abstract Korovkin-type theorems in modular spaces and applications}, journal = {Open Mathematics}, volume = {11}, year = {2013}, pages = {1774-1784}, zbl = {1283.41018}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.doi-10_2478_s11533-013-0288-7} }
Carlo Bardaro; Antonio Boccuto; Xenofon Dimitriou; Ilaria Mantellini. Abstract Korovkin-type theorems in modular spaces and applications. Open Mathematics, Tome 11 (2013) pp. 1774-1784. http://gdmltest.u-ga.fr/item/bwmeta1.element.doi-10_2478_s11533-013-0288-7/
[1] Agratini O., On statistical approximation in spaces of continuous functions, Positivity, 2009, 13(4), 735–743 http://dx.doi.org/10.1007/s11117-008-3002-4[WoS][Crossref] | Zbl 1179.41023
[2] Agratini O., Statistical convergence of a non-positive approximation process, Chaos Solitons Fractals, 2011, 44(11), 977–981 http://dx.doi.org/10.1016/j.chaos.2011.08.003[Crossref][WoS] | Zbl 1278.41010
[3] Altomare F., Korovkin-type theorems and approximation by positive linear operators, Surv. Approx. Theory, 2010, 5, 92–164 | Zbl 1285.41012
[4] Altomare F., Campiti M., Korovkin-type Approximation Theory and its Applications, de Gruyter Stud. Math., 17, Walter de Gruyter, Berlin, 1994 http://dx.doi.org/10.1515/9783110884586[Crossref] | Zbl 0924.41001
[5] Anastassiou G.A., Duman O., Towards Intelligent Modeling: Statistical Approximation Theory, Intell. Syst. Ref. Libr., 14, Springer, Berlin, 2011 http://dx.doi.org/10.1007/978-3-642-19826-7[Crossref] | Zbl 1295.41001
[6] Bardaro C., Boccuto A., Dimitriou X., Mantellini I., Modular filter convergence theorems for abstract sampling-type operators, Appl. Anal. (in press), DOI: 10.1080/00036811.2012.738480 [Crossref] | Zbl 1286.41003
[7] Bardaro C., Mantellini I., Multivariate moment type operators: approximation properties in Orlicz spaces, J. Math. Inequal., 2008, 2(2), 247–259 http://dx.doi.org/10.7153/jmi-02-22[Crossref] | Zbl 1152.41308
[8] Bardaro C., Mantellini I., A Korovkin theorem in multivariate modular function spaces, J. Funct. Spaces Appl., 2009, 7(2), 105–120 http://dx.doi.org/10.1155/2009/863153[Crossref] | Zbl 1195.41021
[9] Bardaro C., Musielak J., Vinti G., Nonlinear Integral Operators and Applications, De Gruyter Ser. Nonlinear Anal. Appl., 9, Walter de Gruyter, Berlin, 2003 http://dx.doi.org/10.1515/9783110199277[Crossref] | Zbl 1030.47003
[10] Belen C., Yildirim M., Statistical approximation in multivariate modular function spaces, Comment. Math., 2011, 51(1), 39–53 | Zbl 1291.41005
[11] Boccuto A., Candeloro D., Integral and ideals in Riesz spaces, Inform. Sci., 2009, 179(17), 2891–2902 http://dx.doi.org/10.1016/j.ins.2008.11.001[Crossref] | Zbl 1185.28016
[12] Boccuto A., Dimitriou X., Modular filter convergence theorems for Urysohn integral operators and applications, Acta Math. Sinica, 2013, 29(6), 1055–1066 http://dx.doi.org/10.1007/s10114-013-1443-6[Crossref][WoS] | Zbl 1268.41018
[13] Boccuto A., Dimitriou X., Modular convergence theorems for integral operators in the context of filter exhaustiveness and applications, Mediterr. J. Math., 2013, 10(2), 823–842 http://dx.doi.org/10.1007/s00009-012-0199-z[WoS][Crossref] | Zbl 1266.41017
[14] Borsík J., Šalát T., On F-continuity of real functions, Tatra Mt. Math. Publ., 1993, 2, 37–42 | Zbl 0788.26004
[15] Demirci K., I-limit superior and limit inferior, Math. Commun., 2001, 6(2), 165–172 | Zbl 0992.40002
[16] Duman O., Özarslan M.A., Erkuş-Duman E., Rates of ideal convergence for approximation operators, Mediterr. J. Math., 2010, 7(1), 111–121 http://dx.doi.org/10.1007/s00009-010-0031-6[WoS][Crossref] | Zbl 1200.41022
[17] Gadjiev A.D., Orhan C., Some approximation theorems via statistical convergence, Rocky Mountain J. Math., 2002, 32(1), 129–138 http://dx.doi.org/10.1216/rmjm/1030539612[Crossref] | Zbl 1039.41018
[18] Karakuş S., Demirci K., Duman O., Statistical approximation by positive linear operators on modular spaces, Positivity, 2010, 14(2), 321–334 http://dx.doi.org/10.1007/s11117-009-0020-9[Crossref][WoS] | Zbl 1193.41014
[19] Katětov M., Product of filters, Comment. Math. Univ. Carolinae, 1968, 9(1), 173–189 | Zbl 0155.50301
[20] Komisarski A., Pointwise I-convergence and I-convergence in measure of sequences of functions, J. Math. Anal. Appl., 2008, 340(2), 770–779 http://dx.doi.org/10.1016/j.jmaa.2007.09.016[Crossref] | Zbl 1139.40002
[21] Korovkin P.P., On convergence of linear positive operators in the spaces of continuous functions, Doklady Akad. Nauk SSSR (N.S.), 1953, 90, 961–964 (in Russian)
[22] Kostyrko P., Šalát T., Wilczynski W., I-convergence, Real Anal. Exchange, 2000/01, 26(2), 669–685
[23] Kuratowski K., Topology I–II, Academic Press/PWN, New York-London/Warsaw, 1966/1968
[24] Lahiri B.K., Das P., I and I*-convergence in topological spaces, Math. Bohem., 2005, 130(2), 153–160 | Zbl 1111.40001
[25] Lorentz G.G., A contribution to the theory of divergent sequences, Acta Math., 1948, 80, 167–190 http://dx.doi.org/10.1007/BF02393648[Crossref] | Zbl 0031.29501
[26] Maligranda L., Korovkin theorem in symmetric spaces, Comment. Math. Prace Mat., 1987, 27(1), 135–140 | Zbl 0635.41030
[27] Mantellini I., Generalized sampling operators in modular spaces, Comment. Math. Prace Mat., 1998, 38, 77–92 | Zbl 0984.47025
[28] Musielak J., Orlicz Spaces and Modular Spaces, Lecture Notes in Math., 1034, Springer, Berlin, 1983