420 research outputs found

    A viscosity iterative technique for equilibrium and fixed point problems in a Hadamard space

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    [EN] The main purpose of this paper is to introduce a viscosity-type proximal point algorithm, comprising of a nonexpansive mapping and a finite sum of resolvent operators associated with monotone bifunctions. A strong convergence of the proposed algorithm to a common solution of a finite family of equilibrium problems and fixed point problem for a nonexpansive mapping is established in a Hadamard space. We further applied our results to solve some optimization problems in Hadamard spaces.Izuchukwu, C.; Aremu, KO.; Mebawondu, AA.; Mewomo, OT. (2019). A viscosity iterative technique for equilibrium and fixed point problems in a Hadamard space. Applied General Topology. 20(1):193-210. https://doi.org/10.4995/agt.2019.10635SWORD193210201K. O. Aremu, C. Izuchukwu, G. C. Ugwunnadi and O. T. Mewomo, On the proximal point algorithm and demimetric mappings in CAT(0) spaces, Demonstr. Math. 51 (2018), 277-294. https://doi.org/10.1515/dema-2018-0022M. Bacák, The proximal point algorithm in metric spaces, Israel J. Math. 194 (2013), 689-701. https://doi.org/10.1007/s11856-012-0091-3M. Bacák and S. Riech, The asymptotic behavior of a class of nonlinear semigroups in Hadamard spaces, J. Fixed Point Theory Appl. 16 (2014), 189-202. https://doi.org/10.1007/s11784-014-0202-3I. D. Berg and I. G. Nikolaev, Quasilinearization and curvature of Alexandrov spaces, Geom. Dedicata 133 (2008), 195-218. https://doi.org/10.1007/s10711-008-9243-3M. Bianchi and S. Schaible, Generalized monotone bifunctions and equilibrium problems, J. Optim Theory Appl. 90 (1996), 31-43. https://doi.org/10.1007/BF02192244Bridson and A. Haefliger, Metric spaces of nonpositive curvature, Springer-Verlag, Berlin, Heidelberg, New York, 1999.F. Bruhat and J. Tits, Groupes réductifs sur un corp local, I. Donneés Radicielles Valuées, Institut des Hautes Études Scientifiques 41 (1972). https://doi.org/10.1007/bf02715544P. Chaoha and A. Phon-on, A note on fixed point sets in CAT(0) spaces, J. Math. Anal. Appl. 320, no. 2 (2006), 983-987. https://doi.org/10.1016/j.jmaa.2005.08.006V. Colao, G. López, G. Marino, V. Martín-Márquez, Equilibrium problems in Hadamard manifolds, J. Math. Anal. Appl. 388 (2012), 61-77. https://doi.org/10.1016/j.jmaa.2011.11.001P. L. Combetes and S. A. Hirstoaga, Equilibrium programming in Hilbert spaces, J. Nonlinear Convex Anal. 6 (2005), 117-136.H. Dehghan and J. Rooin, Metric projection and convergence theorems for nonexpansive mappings in Hadamard spaces, arXiv:1410.1137v1[math.FA]2014.S. Dhompongsa, W. A. Kirk and B. Sims, Fixed points of uniformly Lipschitzian mappings, Nonlinear Anal. 64, no. 4 (2006), 762-772. https://doi.org/10.1016/j.na.2005.09.044S. Dhompongsa and B. Panyanak, On △-convergence theorems in CAT(0) spaces, Comput. Math. Appl. 56 (2008), 2572-2579. https://doi.org/10.1016/j.camwa.2008.05.036J. N. Ezeora and C. Izuchukwu, Iterative approximation of solution of split variational inclusion problems, Filomat, to appear.K. Goebel and S. Reich, Uniform convexity, hyperbolic geometry and nonexpansive mappings, Marcel Dekker, New York, (1984).A. N. Iusem, G. Kassay and W. Sosa, On certain conditions for the existence of solutions of equilibrium problems, Math. Program., Ser. B 116 (2009), 259-273. https://doi.org/10.1007/s10107-007-0125-5C. Izuchukwu, G. C. Ugwunnadi, O. T. Mewomo, A. R. Khan and M. Abbas, Proximal-type algorithms for split minimization problem in P-uniformly convex metric spaces, Numer. Algor., to appear. https://doi.org/10.1007/s11075-018-0633-9B. A. Kakavandi, Weak topologies in complete CAT(0) metric spaces, Proc. Amer. Math. Soc. 141, no. 3 (2013), 1029-1039. https://doi.org/10.1090/S0002-9939-2012-11743-5H. Khatibzadeh and S. Ranjbar, Monotone operators and the proximal point algorithm in complete CAT(0) metric spaces, J. Aust. 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Control Optim. 14 (1976), 877-898. https://doi.org/10.1137/0314056S. Saejung, Halpern's iteration in CAT(0) spaces, Fixed Point Theory Appl. 2010, Art. ID 471781, 13 pp.Y. Song and X. Liu, Convergence comparison of several iteration algorithms for the common fixed point problems, Fixed Point Theory Appl. 2009, Art. ID 824374, 13 pp. https://doi.org/10.1155/2009/824374R. Suparatulatorn, P. Cholamjiak and S. Suantai, On solving the minimization problem and the fixed-point problem for nonexpansive mappings in CAT(0) spaces, Optim. Methods and Software 32 (2017), 182-192. https://doi.org/10.1080/10556788.2016.1219908T. Suzuki, Strong convergence theorems for infinite families of nonexpansive mappings in general Banach spaces, Fixed Point Theory Appl. 1 (2005), 103-123. https://doi.org/10.1155/FPTA.2005.103J. Tang, Viscosity approximation methods for a family of nonexpansive mappings in CAT(0) Spaces, Abstr. Appl. Anal. 2014, Art. ID 389804, 9 pages. G. C. Ugwunnadi, C. Izuchukwu and O. T. 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    On Mixed Equilibrium Problems in Hadamard Spaces

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    The main purpose of this paper is to study mixed equilibrium problems in Hadamard spaces. First, we establish the existence of solution of the mixed equilibrium problem and the unique existence of the resolvent operator for the problem. We then prove a strong convergence of the resolvent and a ?-convergence of the proximal point algorithm to a solution of the mixed equilibrium problem under some suitable conditions. Furthermore, we study the asymptotic behavior of the sequence generated by a Halpern-type PPA. Finally, we give a numerical example in a nonlinear space setting to illustrate the applicability of our results. Our results extend and unify some related results in the literature. - 2019 Chinedu Izuchukwu et al.ledgments .e publication of this article was funded by the Qatar National Library. .e first and third authors acknowledge the bursary and financial support from Department of Science and Technology and National Research Foundation, Republic of South Africa Center of Excellence in Mathematical and Statistical Sciences (DST-NRF COE-MaSS) Doctoral Bursary. .e fourth author is supported in part by the National Research Foundation (NRF) of South Africa Incentive Funding for Rated Researchers (Grant NumberScopu

    Nonexpansive mappings and monotone vector fields in Hadamard manifolds

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    This paper briefly surveys some recent advances in the investigation of nonexpansive mappings and monotone vector fields, focusing in the extension of basic results of the classical nonlinear functional analysis from Banach spaces to the class of nonpositive sectional curvature Riemannian manifolds called Hadamard manifolds. Within this setting, we first analyze the problem of finding fixed points of nonexpansive mappings. Later on, different classes of monotonicity for set-valued vector fields and the relationship between some of them will be presented, followed by the study of the existence and approximation of singularities for such vector fields. We will discuss about variational inequality and minimization problems in Hadamard manifolds, stressing the fact that these problems can be solved by means of the iterative approaches for monotone vector fields

    A study of optimization and fixed point problems in certain geodesic metric spaces.

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    Doctoral Degree. University of KwaZulu-Natal, Durban.Abstract available in PDF

    Iterative algorithms for approximating solutions of some optimization problems in Hadamard spaces.

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    Masters Degree. University of KwaZulu-Natal, Durban.Abstract available in PDF.Some text in red

    Proximal-type algorithms for split minimization problem in P-uniformly convex metric spaces

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    In this paper, we study strong convergence of some proximal-type algorithms to a solution of split minimization problem in complete p-uniformly convex metric spaces. We also analyse asymptotic behaviour of the sequence generated by Halpern-type proximal point algorithm and extend it to approximate a common solution of a finite family of minimization problems in the setting of complete p-uniformly convex metric spaces. Furthermore, numerical experiments of our algorithms in comparison with other algorithms are given to show the applicability of our results.http://link.springer.com/journal/110752019-11-19hj2018Mathematics and Applied Mathematic

    Theory and Application of Fixed Point

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    In the past few decades, several interesting problems have been solved using fixed point theory. In addition to classical ordinary differential equations and integral equation, researchers also focus on fractional differential equations (FDE) and fractional integral equations (FIE). Indeed, FDE and FIE lead to a better understanding of several physical phenomena, which is why such differential equations have been highly appreciated and explored. We also note the importance of distinct abstract spaces, such as quasi-metric, b-metric, symmetric, partial metric, and dislocated metric. Sometimes, one of these spaces is more suitable for a particular application. Fixed point theory techniques in partial metric spaces have been used to solve classical problems of the semantic and domain theory of computer science. This book contains some very recent theoretical results related to some new types of contraction mappings defined in various types of spaces. There are also studies related to applications of the theoretical findings to mathematical models of specific problems, and their approximate computations. In this sense, this book will contribute to the area and provide directions for further developments in fixed point theory and its applications
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