Monotone vector fields on a geodesic space with curvature bounded above by a general real number
Keywords:
Set-valued vector field, monotonicity, geodesic space, subdifferential, equilibrium problemAbstract
In this paper, we propose a notion of monotone set-valued vector fields on geodesic spaces with curvature bounded above, and define a resolvent operator of a monotone vector field. Particularly, we investigate a relation between zero points of a monotone vector field and fixed points of its resolvent operator, and asymptotic behaviours of resolvent operators. Finally, we consider two examples of monotone vector fields corresponding to the subdifferential of convex functions. To constitute the examples, we consider resolvent operators of convex functions and equilibrium problems, respectively.
References
[1] K. Aoyama, Y. Kimura, and W. Takahashi, Maximal monotone operators and maximal monotone functions for equilibrium problem, J. Convex Anal. 15 (2008), 395–409.
[2] D. Ariza-Ruiz, C. Li, and G. López-Acedo, The Schauder fixed point theorem in geodesic spaces, J. Math. Anal. Appl. 417 (2014), 345–360.
[3] M. Bačák, Convex analysis and optimization in Hadamard spaces, De Gruyter, Berlin, 2014.
[4] I. D. Berg and I. G. Nikolaev, Quasilinearization and curvature of Alexandrov spaces, Geom. Dedicata 133 (2008), 195–218.
[5] M. R. Bridson and Haefliger, Metric spaces of non-positive curvature, Springer-Verlag, Berlin, 1999.
[6] P. Chaipunya, F. Kohsaka, and P. Kumam, Monotone vector fields and generation of nonexpansive semigroups in complete CAT(0) spaces, Numer. Funct. Anal. Optim. 42 (2021), 989–1018.
[7] R. Espínola and A. Fernández-León, CAT(k)-spaces, weak convergence and fixed points, J. Math. Anal. Appl. 353 (2009), 410–427.
[8] T. Kajimura and Y. Kimura, A vicinal mapping on geodesic spaces, Proceedings of International Conference on Nonlinear Analysis and Convex Analysis & International Conference on Optimization: Techniques and Applications –I– (Hakodate, Japan, 2019) (Y. Kimura, M. Muramatsu, W. Takahashi, and A. Yoshise, eds.).
[9] T. Kajimura and Y. Kimura, The proximal point algorithm in complete geodesic spaces with negative curvature, Adv. Theory Nonlinear Anal. Appl. 3 (2019), 192–200.
[10] B. A. Kakavandi and M. Amini, Duality and subdifferential for convex functions on complete CAT(0) metric space, Proc. Amer. Math. Soc. 141 (2013), 1029–1039.
[11] H. Khatibzadeh and S. Ranjbar, Monotone operators and the proximal point algorithm in complete CAT(0) spaces, J. Aust. Math. Soc. 103 (2017), 70–90.
[12] Y. Kimura, Convergence of a sequence of sets in a Hadamard space and the shrinking projection method for a real Hilbert ball, Abstr. Appl. Anal. 2010 (2010), 11pp.
[13] Y. Kimura, Resolvents of equilibrium problems on a complete geodesic space with curvature bounded above, Carpathian J. Math 37 (2021), 463–476.
[14] Y. Kimura and Y. Kishi, Equilibrium problems and their resolvents in Hadamard spaces, J. Nonlinear and Convex Anal. 19 (2018), 1503–1513.
[5] Y. Kimura and F. Kohsaka, Spherical nonspreadingness of resolvents of convex functions in geodesic spaces, J. Fixed Point Theory Appl. (2016), 93–115.
[16] Y. Kimura and F. Kohsaka, The proximal point algorithm in geodesic spaces with curvature bounded above, Linear Nonlinear Anal. 3 (2017), 133–148.
[17] Y. Kimura and T. Ogihara, Resolvents of equilibrium problems in a complete geodesic space with negative curvature, arXiv: 2207. 10903 math. FAA].
[18] Y. Kimura and K. Sasaki, Sufficient conditions for perturbations to define the resolvent of the equilibrium problem on complete geodesic spaces, J. Fixed Point Theory Appl. 25 (2023), 24pp.
[19] Y. Kimura and K. Satô, Convergence of subsets of a complete geodesic space with curvature bounded above, Nonlinear Anal. 75 (2012), 5079–5085.
[20] Y. Kimura and S. Sudo, New type parallelogram laws in Banach spaces and geodesic spaces with curvature bounded above, Arab. J. Math. 12 (2023), 389–412.
[21] Y. Kimura and S. Sudo, Tangent spaces and a metric on geodesic spaces, RIMS Kôkyûroku (Study on Nonlinear Analysis and Convex Analysis), vol. 2240, 2023, pp. 7–19.
[22] W. A. Kirk and B. Panyanak, A concept of convergence in geodesic spaces, Nonlinear Anal. 68 (2008), 3689–3696.
[23] C. Li, G. López, V. Martín-Márquez, and J. H. Wang, Monotone and accretive vector fields on Riemannian manifolds, J. Optim. Theory Appl. 146 (2010), 691–708.
[24] C. Li, G. López, V. Martín-Márquez, and J. H. Wang, Resolvents of set-valued monotone vector fields in Hadamard manifolds, Set-Valued Anal. 19 (2011), 361–383.
[25] U. F. Mayer, Gradient flows on nonpositively curved metric spaces and harmonic map, Comm. Anal. Geom. 6 (1998), 199–253.
[26] T. Ogihara, Resolvents for equilibrium problems and a convergence theorem using a balanced mapping in geodesic spaces, Master’s thesis, Toho University, 2024.
[27] R. T. Rockafellar, Monotone operators and the proximal point algorithm, SIAM J. Control Optimization 14 (1976), 877–898.
[28] S. Shabanian and S. M. Vaezpour, A minimax inequality and its applications to fixed point theorems in CAT(0) spaces, Fixed Point Theory Appl. 2011 (2011), 9pp.
[29] S. Sudo, Parallelogram laws on geodesic spaces, Master’s thesis, Toho University, 2023.
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