http://www.math.sci.nu.ac.th/ojs302/index.php/jnao/issue/feed Journal of Nonlinear Analysis and Optimization: Theory & Applications 2021-04-01T00:00:00+07:00 Narin Petrot narinp@nu.ac.th Open Journal Systems <p><strong>Journal of Nonlinear Analysis and Optimization: Theory &amp; Applications</strong> is a peer-reviewed, open-access international journal, that devotes to the publication of original articles of current interest in every theoretical, computational, and applicational aspect of nonlinear analysis, convex analysis, fixed point theory, and optimization techniques and their applications to science and engineering. All manuscripts are refereed under the same standards as those used by the finest-quality printed mathematical journals. Accepted papers will be published in two issues annually in March and September, free of charge. This journal was conceived as the main scientific publication of the Center of Excellence in Nonlinear Analysis and Optimization, Naresuan University, Thailand.</p> <p> </p> http://www.math.sci.nu.ac.th/ojs302/index.php/jnao/article/view/617 Balanced mappings and an iterative scheme in complete geodesic spaces 2020-12-19T05:18:22+07:00 T. Kajimura 6518004k@st.toho-u.jp K. Kasahara 7518001k@st.toho-u.jp Y. Kimura yasunori@is.sci.toho-u.ac.jp K. Nakagawa 7517201n@st.toho-u.jp <p>In this paper, we define a balanced mapping by a maximizer of a certain function generated by a finite number of mappings without regard to their order and find its fundamental properties in a complete CAT(1) space. Furthermore, we approximate a fixed point of a balanced mapping which is generated by a finite number of quasinonexpansive and Delta-demiclosed mappings by using Mann's iterative scheme.</p> 2021-04-01T00:00:00+07:00 Copyright (c) 2021 Journal of Nonlinear Analysis and Optimization: Theory & Applications http://www.math.sci.nu.ac.th/ojs302/index.php/jnao/article/view/625 A practical approach to optimization 2020-12-15T06:18:04+07:00 W. Jirakitpuwapat wachirapong.jira@hotmail.com P. Kumam poom.kumam@mail.kmutt.ac.th K. Khammahawong k.konrawut@gmail.com S. Dhompongsa sompong.dho@kmutt.ac.th <p>We present a new approach for finding a minimal value of an arbitrary function assuming only its continuity. The process avoids verifying Lagrange- or KKT-conditions. The method enables us to obtain a Brouwer fixed point (of a continuous function mapping from a cube into itself).</p> 2021-04-01T00:00:00+07:00 Copyright (c) 2021 Journal of Nonlinear Analysis and Optimization: Theory & Applications http://www.math.sci.nu.ac.th/ojs302/index.php/jnao/article/view/632 Radius of the perturbation of the objective function preserves the KKT condition in convex optimization 2021-02-06T11:08:07+07:00 K. Ishibashi kuroiwa@riko.shimane-u.ac.jp D. Kuroiwa kuroiwa@riko.shimane-u.ac.jp <p style="-qt-block-indent: 0; text-indent: 0px; margin: 0px;">The problem to find the maximum radius of the perturbation of the objective function which preserves the KKT condition at a feasible point is studied. The maximum radius of the problem is described, and certain values concerned with the extreme direction of a positive polar cone of the union of the subdifferentials of the active constraint functions at the point are observed.</p> 2021-04-01T00:00:00+07:00 Copyright (c) 2021 Journal of Nonlinear Analysis and Optimization: Theory & Applications http://www.math.sci.nu.ac.th/ojs302/index.php/jnao/article/view/644 Common Fixed point Theorems for some contractive condition with $\varphi$-mapping in Complex valued b-metric spaces 2021-03-14T17:11:25+07:00 I. Inchan peissara@windowslive.com K. Gajai warinsinee@hotmail.com T. Yuying tadchai99@hotmail.com S. Youyen saard.youyen@gmail.com W. Chantakun warinsinee@hotmail.com <p>In this paper, by using the concept of $\varphi$-mappings introduced by Mohanta and Maitra [8], we can prove the existence and the uniqueness of common fixed points for some generalized contractive mappings in complex-valued b-metric spaces. Our results extend and improve the results of Tripathi and Dubey [12] and many others.</p> 2021-04-01T00:00:00+07:00 Copyright (c) 2021 Journal of Nonlinear Analysis and Optimization: Theory & Applications http://www.math.sci.nu.ac.th/ojs302/index.php/jnao/article/view/618 Reforms of a generalized KKMF principle 2020-10-16T04:07:54+07:00 S. Park shpark@math.snu.ac.kr <p>In 2005, Ben-El-Mechaiekh, Chebbi, and Florenzano obtained a generalization of Ky Fan’s 1984 KKM theorem on the intersection of a family of closed sets on non-compact convex sets in a topological vector space. They also extended the Fan-Browder fixed point theorem to multimaps on non-compact convex sets. In this article, we deduce the better abstract versions of such results from a general KKM theorem on abstract convex spaces in our previous works.</p> 2021-04-01T00:00:00+07:00 Copyright (c) 2021 Journal of Nonlinear Analysis and Optimization: Theory & Applications