Abstract
Let \(G:H\rightarrow H\) and \(K: H\rightarrow H\) be monotone mappings that are either sequentially weakly continuous or continuous, where H is a real Hilbert space. In this work, we introduce two new iterative methods for approximating solutions of the Hammerstein equation \(u+GKu=0\), if they exist. The first iterative method is shown to always converge weakly to an element in the solution set of the Hammerstein equation if this solution set is nonempty. The second iterative method is a modification of the first method to upgrade weak convergence to strong convergence. Convergence results are obtained without requiring the maps to be bounded. Numerical examples are provided to demonstrate the convergence of one of these methods. Comparisons with some existing methods show that the method is cost effective in terms of the number of iterations required to obtain a solution and the computational time.
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References
Allouch, C., Sbibih, D., Tahrichi, M.: Legendre superconvergent Galerkin-collocation type methods for Hammerstein equations. J. Comput. Appl. Math. 353, 253–264 (2019). https://doi.org/10.1016/j.cam.2018.12.040
Appell, J., Benavides, T.D.: Nonlinear Hammerstein equations and functions of bounded Riesz–Medvedev variation. Topol. Methods Nonlinear Anal. 47, 319–332 (2016)
Bello, A.U., Omojola, M.T., Yahaya, J.: An inertial-type algorithm for approximation of solutions of Hammerstein integral inclusions in Hilbert spaces. Fixed Point Theory Algorithms Sci. Eng. 2021(8), 22 (2021)
Blum, E., Oettli, W.: From optimization and variational inequality to equilibrium problems. Math. Stud. 63, 123–145 (1994)
Boikanyo, O.A.: The generalized contraction proximal point algorithm with square-summable errors. Afr. Mat. 28, 321–332 (2017)
Brézis, H., Browder, F.E.: Some new results about Hammerstein equations. Bull. Am. Math. Soc. 80, 568–572 (1974)
Brézis, H., Browder, F.E.: Existence theorems for nonlinear integral equations of Hammerstein type. Bull. Am. Math. Soc. 81, 73–78 (1975)
Brézis, H., Browder, F.E.: Nonlinear integral equations and systems of Hammerstein type. Adv. Math. 18, 115–147 (1975)
Browder, F.E.: The solvability of nonlinear functional equations. Duke Math. J. 30, 557–566 (1963)
Browder, F.E.: Nonlinear mappings of non-expansive and accretive operators in Banach spaces. Bull. Am. Math. Soc. 73, 875–882 (1967)
Browder, F.E.: Nonlinear functional analysis and nonlinear integral equations of Hammerstein and Urysohn type. In: Zarantonello, E. (ed.) Contributions to Nonlinear Functional Analysis, pp. 425–500. Academic Press, New York (1971)
Browder, F.E., Gupta, C.P.: Nonlinear monotone operators and integral equations of Hammerstein type. Bull. Am. Math. Soc. 75, 1347–1353 (1969)
Browder, F.E., De Figueiredo, D.G., Gupta, C.P.: Maximal monotone operators and nonlinear integral equations of Hammerstein type. Bull. Am. Math. Soc. 76, 700–705 (1970)
Chepanovich, R.S.: Nonlinear Hammerstein equations and fixed points. Publ. Inst. Math. (Belgr.) 35, 119–123 (1984)
Chidume, C.E., Bello, A.U.: An iterative algorithm for approximating solutions of Hammerstein equations with monotone maps in Banach spaces. Appl. Math. Comput. 313, 408–417 (2017)
Chidume, C.E., Djitte, N.: Iterative approximation of solutions of nonlinear equations of Hammerstein-type. Nonlinear Anal. 70, 4086–4092 (2009)
Chidume, C.E., Djitte, N.: Approximation of solutions of Hammerstein equations with bounded strongly accretive nonlinear operator. Nonlinear Anal. 70, 4071–4078 (2009)
Chidume, C.E., Djitte, N.: An iterative method for solving nonlinear integral equations of Hammerstein type. Appl. Math. Comput. 219, 5613–5621 (2013)
Chidume, C.E., Idu, K.O.: Approximation of zeros of bounded maximal monotone maps, solutions of Hammerstein integral equations and convex minimization problems. Fixed Point Theory Appl. (2016). https://doi.org/10.1186/s13663-016-0582-8
Chidume, C.E., Ofoedu, E.U.: Solution of nonlinear integral equations of Hammerstein type. Nonlinear Anal. 74, 4293–4299 (2011)
Chidume, C.. E., Shehu, Y.: Strong convergence theorem for approximation of solutions of equations of Hammerstein type. Nonlinear Anal. Theory Methods Appl. 75(14), 5664–5671 (2012)
Chidume, C.E., Shehu, Y.: Approximation of solutions of generalized equations of Hammerstein type. Comput. Math. Appl. 63, 966–974 (2012)
Chidume, C.E., Shehu, Y.: Iterative approximation of solutions of equations of Hammerstein type in certain Banach spaces. Appl. Math. Comput. 219, 5657–5667 (2013)
Chidume, C.E., Shehu, Y.: Approximation of solutions of equations Hammerstein type in Hilbert spaces. Fixed Point Theory 16(1), 91–102 (2015)
Chidume, C.E., Zegeye, H.: Approximation of solutions of nonlinear equations of monotone and Hammerstein-type. Appl. Anal. 82(8), 747–758 (2003)
Chidume, C.E., Zegeye, H.: Iterative approximation of solutions of nonlinear equation of Hammerstein-type. Abstr. Appl. Anal. 6, 353–367 (2003)
Chidume, C.E., Zegeye, H.: Approximation of solutions nonlinear equations of Hammerstein type in Hilbert space. Proc. Am. Math. Soc. 133, 851–858 (2005)
Chidume, C.E., Adamu, A., Chinwendu, L.O.: Approximation of solutions of Hammerstein equations with monotone mappings in real Banach spaces. Carpath. J. Math. 35(3), 305–316 (2019)
Chidume, C.E., Nnakwe, M.O., Adamu, A.: A strong convergence theorem for generalized-\(\Phi \)-strongly monotone maps, with applications. Fixed Point Theory Appl. (2019). https://doi.org/10.1186/s13663-019-0660-9
Chidume, C.E., Adamu, A., Okereke, L.C.: Iterative algorithms for solutions of Hammerstein equations in real Banach spaces. Fixed Point Theory Appl. 2020, 4 (2020). https://doi.org/10.1186/s13663-020-0670-7
Daman, O., Tufa, A.R., Zegeye, H.: Approximating solutions of Hammerstein type equations in Banach spaces. Quaest. Math. 42(5), 561–577 (2019)
De Figueiredo, D.G., Gupta, C.P.: On the variational methods for the existence of solutions to nonlinear equations of Hammerstein type. Bull. Am. Math. Soc. 40, 470–476 (1973)
Djitte, N., Sene, M.: An iterative algorithm for approximating solutions of Hammerstein integral equations. Numer. Funct. Anal. Optim. 34(12), 1299–1316 (2013)
Dolezal, V.: Monotone operators and applications in control and network theory. In: Studies in Automation and Control, Vol. 2. Elsevier Scientific, New York (1978)
Goebel, K., Kirk, W.A.: Topics on Metric Fixed Point Theory. Cambridge University Press, Cambridge (1990)
Kazemi, M.: Triangular functions for numerical solution of the nonlinear Volterra integral equations. J. Appl. Math. Comput. 1–24 (2021)
Kazemi, M.: On existence of solutions for some functional integral equations in Banach algebra by fixed point theorem. Int. J. Nonlinear Anal. Appl. 13(1), 451–466 (2022)
Kazemi, M., Ezzati, R.: Existence of solution for some nonlinear two-dimensional Volterra integral equations via measures of noncompactness. Appl. Math. Comput. 275, 165–171 (2016)
Kürkçü, O.K.: An evolutionary numerical method for solving nonlinear fractional Fredholm–Volterra–Hammerstein integro-differential-delay equations with a functional bound. Int. J. Comput. Math. https://doi.org/10.1080/00207160.2022.2095510
Maingé, P.E.: Strong convergence of projected subgradiant method for nonsmooth and nonstrictily convex minimization. Set-Valued Anal. 16, 899–912 (2008)
Micula, S., Cattani, C.: On a numerical method based on wavelets for Fredholm–Hammerstein integral equations of the second kind. Math. Methods Appl. Sci. 41, 9103–9115 (2018)
Minjibir, M.S., Mohammed, I.: Iterative algorithms for solutions of Hammerstein integral inclusions. Appl. Math. Comput. 320, 389–399 (2018)
Neamprem, K., Klangrak, A., Kaneko, H.: Taylor–Series expansion methods for multivariate Hammerstein integral equations. Int. J. Appl. Math. 47(4), 1–5 (2017)
Ofoedu, E.U., Onyi, C.E.: New implicit and explicit approximation methods for solutions of integral equations of Hammerstein type. Appl. Math. Comput. 246, 628–637 (2014)
Opial, Z.: Weak convergence of the sequence of successive approximations for non-expansive mappings. Bull. Am. Math. Soc. 73, 591–597 (1967)
Pascali, D., Sburlan, S.: Nonlinear mappings of monotone type. Editura Academia, Bucharest (1978)
Shehu, Y.: Strong convergence theorem for integral equations of Hammerstein type in Hilbert spaces. Appl. Math. Comput. 231, 140–147 (2014)
Tufa, A.R., Zegeye, H., Thuto, M.: Iterative solutions of nonlinear integral equations of Hammerstein type. Int. J. Anal. Appl. 9(2), 129–141 (2015)
Uba, M.O., Uzochukwu, M.I., Onyido, M.A.: Algorithm for approximating solutions of Hammerstein integral equations with maximal monotone operators. Indian J. Pure Appl. Math. 48(3), 391–410 (2017)
Wang, J.: Numerical algorithm for two-dimensional nonlinear Volterra–Fredholm integral equations and fractional integro-differential equations (of Hammerstein and mixed types). Eng. Comput. 38(9), 3548–3563 (2021). https://doi.org/10.1108/EC-06-2020-0353
Xu, H.K.: Another control condition in an iterative method for nonexpansive mappings. Bull. Aust. Math. Soc. 65, 109–113 (2002)
Zegeye, H., Malonza, D.M.: Hybrid approximation of solutions of integral equations of the Hammerstein type. Arab. J. Math. 2, 221–232 (2013)
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Boikanyo, O.A., Zegeye, H. New iterative methods for finding solutions of Hammerstein equations. J. Appl. Math. Comput. 69, 1465–1490 (2023). https://doi.org/10.1007/s12190-022-01795-y
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DOI: https://doi.org/10.1007/s12190-022-01795-y