×

Metric Fourier approximation of set-valued functions of bounded variation. (English) Zbl 1475.42008

The main topic of the paper is an adaptation of the trigonometric Fourier series to set-valued functions of bounded variation with compact images. The authors also try to gain error bounds under minimal regularity requirements on the approximated multifunctions. This analysis exploits properties of maps of bounded variation from [V. V. Chistyakov, J. Dyn. Control Syst. 3, No. 2, 261–289 (1997; Zbl 0940.26009)]. The authors define a metric analogue of the partial sums of the Fourier series of a multifunction via convolutions with the Dirichlet kernel. To define these convolutions the authors introduce a new weighted metric integral. The study of the error bounds of the approximations leads to the introduction of a new one-sided local moduli of continuity and a one-sided local quasi-moduli of continuity. The main result of the paper is an analogy of the classical Dirichlet-Jordan Theorem for real functions. In particular, if a multifunction \(F\) of bounded variation is continuous at a point \(x\), then its metric Fourier approximants at \(x\) converge to \(F(x)\). This convergence is uniform on bounded closed intervals in which \(F\) is continuous. At a point of discontinuity the limit set is determined by the values of the metric selections of \(F\).

MSC:

42A20 Convergence and absolute convergence of Fourier and trigonometric series
42A10 Trigonometric approximation
26E25 Set-valued functions
28B20 Set-valued set functions and measures; integration of set-valued functions; measurable selections
28C20 Set functions and measures and integrals in infinite-dimensional spaces (Wiener measure, Gaussian measure, etc.)
42A24 Summability and absolute summability of Fourier and trigonometric series
54C60 Set-valued maps in general topology

Citations:

Zbl 0940.26009

References:

[1] Ambrosio, L.; Tilli, P., Topics on Analysis in Metric Spaces (2004), Oxford: Oxford University Press, Oxford · Zbl 1080.28001
[2] Anastassiou, GA, Fuzzy Mathematics: Approximation Theory (2010), Berlin: Springer, Berlin · Zbl 1476.41001 · doi:10.1007/978-3-642-11220-1
[3] Artstein, Z., Piecewise linear approximations of set-valued maps, J. Approx. Theory, 56, 41-47 (1989) · Zbl 0675.41041 · doi:10.1016/0021-9045(89)90131-7
[4] Aubin, J-P; Frankowska, H., Set-Valued Analysis (1990), Boston: Birkhäuser Boston Inc., Boston · Zbl 0713.49021
[5] Aumann, RJ, Integrals of set-valued functions, J. Math. Anal. Appl., 12, 1-12 (1965) · Zbl 0163.06301 · doi:10.1016/0022-247X(65)90049-1
[6] Babenko, VF; Babenko, VV; Polishchuk, MV, Approximation of some classes of set-valued periodic functions by generalized trigonometric polynomials, Ukrainian Math. J., 68, 4, 502-514 (2016) · Zbl 1490.42003 · doi:10.1007/s11253-016-1237-y
[7] Baier, R.: Mengenwertige Integration und die diskrete Approximation erreichbarer Mengen (German) [Set-valued integration and the discrete approximation of attainable sets], Dissertation, Universität Bayreuth. Bayreuth. Math. Schr. No. 50 (1995) · Zbl 0841.65013
[8] Baier, R.; Farkhi, E., Regularity and integration of set-valued maps represented by generalized Steiner points, Set-Valued Anal., 15, 2, 185-207 (2007) · Zbl 1144.28005 · doi:10.1007/s11228-006-0038-0
[9] Baier, R., Lempio, F.: Computing Aumann’s integral, In: Modeling techniques for uncertain systems (Sopron, 1992), Progr. Systems Control Theory, 18, Birkhäuser Boston, Boston, MA, 1994, 71-92 · Zbl 0828.65021
[10] Baier, R., Lempio, F.: Approximating reachable sets by extrapolation methods. In: Peters, A.K. (Eds.), Curves and surfaces in geometric design (Chamonix-Mont-Blanc, 1993), Wellesley, MA, 1994, 9-18 · Zbl 0813.65099
[11] Baier, R.; Perria, G., Set-valued Hermite interpolation, J. Approx. Theory, 163, 1349-1372 (2011) · Zbl 1252.41002 · doi:10.1016/j.jat.2010.11.004
[12] Bede, B.; Iovane, G.; Esposito, I., Fuzzy Fourier transforms and their application to fingerprint identification, J. Discrete Math. Sci. Cryptogr., 8, 1, 59-79 (2005) · Zbl 1086.94046 · doi:10.1080/09720529.2005.10698021
[13] Berdysheva, EE; Dyn, N.; Farkhi, E.; Mokhov, A., Metric approximation of set-valued functions of bounded variation, J. Comput. Appl. Math., 349, 251-264 (2019) · Zbl 1405.26029 · doi:10.1016/j.cam.2018.09.039
[14] Campiti, M., Korovkin-type approximation in spaces of vector-valued and set-valued functions, Appl. Anal., 98, 2486-2496 (2019) · Zbl 1426.41023 · doi:10.1080/00036811.2018.1463522
[15] Chistyakov, VV, On mappings of bounded variation, J. Dyn. Control Syst., 3, 261-289 (1997) · Zbl 0940.26009 · doi:10.1007/BF02465896
[16] Dontchev, A.L., Farkhi, E.M.: An averaged modulus of continuity for multivalued maps and its applications to differential inclusions, In: Constructive theory of functions (Varna, 1987), Publ. House Bulgar. Acad. Sci., Sofia, pp. 127-131 (1988) · Zbl 0718.34016
[17] Donchev, T.; Farkhi, E., Moduli of smoothness of vector valued functions of a real variable and applications, Numer. Funct. Anal. Optim., 11, 497-509 (1990) · Zbl 0699.65039 · doi:10.1080/01630569008816385
[18] Dyn, N.; Farkhi, E., Spline subdivision schemes for convex compact sets, J. Comput. Appl. Math., 119, 1-2, 133-144 (2000) · Zbl 0970.65016 · doi:10.1016/S0377-0427(00)00375-7
[19] Dyn, N., Farkhi, E.: Spline subdivision schemes for compact sets with metric averages, In: Trends in approximation theory (Nashville, TN, 2000). Innov. Appl. Math., Vanderbilt Univ. Press, Nashville, TN, pp. 93-102 (2001) · Zbl 1112.41301
[20] Dyn, N.; Farkhi, E., Set-valued approximations with Minkowski averages – convergence and convexification rates, Numer. Funct. Anal. Optim., 25, 363-377 (2004) · Zbl 1074.41011 · doi:10.1081/NFA-120039682
[21] Dyn, N.; Farkhi, E.; Mokhov, A., Approximations of set-valued functions by metric linear operators, Constr. Approx., 25, 193-209 (2007) · Zbl 1123.26024 · doi:10.1007/s00365-006-0632-9
[22] Dyn, N.; Farkhi, E.; Mokhov, A., Approximations of Set-Valued Functions: Adaptation of Classical Approximation Operators (2014), London: Imperial College Press, London · Zbl 1321.41034 · doi:10.1142/p905
[23] Dyn, N.; Farkhi, E.; Mokhov, A., The metric integral of set-valued functions, Set-Valued Var. Anal., 26, 867-885 (2018) · Zbl 1405.26030 · doi:10.1007/s11228-017-0403-1
[24] Dyn, N.; Mokhov, A., Approximations of set-valued functions based on the metric average, Rend. Mat. Appl. VII. Ser., 26, 3-4, 249-266 (2006) · Zbl 1156.26307
[25] Kadak, U., Başar, F.: On Fourier Series of Fuzzy-Valued Functions. Sci. World J. (2014). doi:10.1155/2014/782652 · Zbl 1292.54004
[26] Kolmogorov, A.; Fomin, S., Introductory Real Analysis (1975), New York: Dover Publ, New York
[27] Lempio, F.: Set-valued interpolation, differential inclusions, and sensitivity in optimization, In: Recent developments in well-posed variational problems, Math. Appl., 331, Kluwer Acad. Publ., Dordrecht, pp. 137-169 (1995) · Zbl 0868.34011
[28] Mureşan, M., Set-valued approximation of multifunctions, Stud. Univ. Babeş-Bolyai, Math., 55, 1, 107-148 (2010) · Zbl 1224.41072
[29] Nikolskĭ, M.S.: Approximation of convex-valued continuous multivalued mappings (Russian), Dokl. Akad. Nauk SSSR 308(5), 1047-1050 (1989); translation in Soviet Math. Dokl. 40(2), 406-409 (1990) · Zbl 0717.41066
[30] Nikolskĭ, MS, Approximation of continuous convex-valued multivalued mappings (Russian), Optimization, 21, 2, 209-214 (1990) · Zbl 0719.54027 · doi:10.1080/02331939008843537
[31] Nikolskĭ, M.S.: On the approximation of set-valued mappings in a uniform (Chebyshev) metric, In: Nonlinear synthesis (Sopron, 1989), Progr. Systems Control Theory, 9, Birkhäuser Boston, Boston, MA, 1991, 224-231 · Zbl 0749.41032
[32] Nikolskĭ, M.S.: Local approximation of first order to set-valued mappings, In: Set-valued analysis and differential inclusions (Pamporovo, 1990), Progr. Systems Control Theory, 16, Birkhäuser Boston, Boston, MA, 1993, 149-156 · Zbl 0804.49017
[33] Rockafellar, RT; Wets, R., Variational Analysis (1998), Berlin: Springer, Berlin · Zbl 0888.49001 · doi:10.1007/978-3-642-02431-3
[34] Sendov, B.; Popov, V., The Averaged Moduli of Smoothness: Applications in Numerical Methods and Approximation (1988), New York: Wiley, New York · Zbl 0653.65002
[35] Schneider, R., Convex Bodies: The Brunn-Minkowski Theory (1993), Cambridge: Cambridge University Press, Cambridge · Zbl 0798.52001 · doi:10.1017/CBO9780511526282
[36] Veliov, VM, Discrete approximations of integrals of multivalued mappings, C. R. Acad. Bulgare Sci., 42, 12, 51-54 (1989) · Zbl 0697.41019
[37] Vitale, RA, Approximations of convex set-valued functions, J. Approx. Theory, 26, 301-316 (1979) · Zbl 0422.41016 · doi:10.1016/0021-9045(79)90067-4
[38] Yavuz, E., On the resummation of series of fuzzy numbers via generalized Dirichlet and generalized factorial series, J. Intell. Fuzzy Syst., 37, 8199-8206 (2019) · doi:10.3233/JIFS-190632
[39] Zygmund, A., Trigonometric Series, 2 edition (1959), Cambridge: Cambridge University Press, Cambridge · Zbl 0085.05601
This reference list is based on information provided by the publisher or from digital mathematics libraries. Its items are heuristically matched to zbMATH identifiers and may contain data conversion errors. In some cases that data have been complemented/enhanced by data from zbMATH Open. This attempts to reflect the references listed in the original paper as accurately as possible without claiming completeness or a perfect matching.