publication

Fumiaki Kohsaka

Publications and Oral Presentations

Papers (in refereed journals and refereed proceedings)

• 1. Fumiaki Kohsaka and Wataru Takahashi, Approximating zero points of accretive operators in strictly convex Banach spaces, Proceedings of the Second International Conference on Nonlinear Analysis and Convex Analysis, 191--196, 2003.

  2. Fumiaki Kohsaka and Wataru Takahashi, Minimization theorem in a Banach space and its applications, Scientiae Mathematicae Japonicae 59, No.3 (2004), 429--436.

  3. Fumiaki Kohsaka and Wataru Takahashi, Strong convergence of an iterative sequence for maximal monotone operators in a Banach space, Abstract and Applied Analysis 2004, No.3 (2004), 239--249.

  4. Fumiaki Kohsaka and Wataru Takahashi, Iterative scheme for finding a common point of infinitely many convex sets in a Banach space, Journal of Nonlinear and Convex Analysis 5, No.3 (2004), 407--414.

  5. Shoji Kamimura, Fumiaki Kohsaka, and Wataru Takahashi, Weak and strong convergence theorems for maximal monotone operators in a Banach space, Set-Valued Analysis 12, No.4 (2004), 417--429.

  6. Fumiaki Kohsaka and Wataru Takahashi, Weak and strong convergence theorems for minimax problems in Banach spaces, Proceedings of the Third International Conference on Nonlinear Analysis and Convex Analysis, 203--215, 2004.

  7. Fumiaki Kohsaka and Wataru Takahashi, Minimization theorems in Banach spaces with applications, Proceedings of the International Symposium on Banach and Function Spaces, 301--313, 2004.

  8. Fumiaki Kohsaka and Wataru Takahashi, Proximal point algorithms with Bregman functions in Banach spaces, Journal of Nonlinear and Convex Analysis 6, No.3 (2005), 505--523.

  9. Fumiaki Kohsaka and Wataru Takahashi, Weak and strong convergence to common points of families of convex sets in Banach spaces, Proceedings of the Fourth International Conference on Nonlinear Analysis and Convex Analysis, 261--275, 2007.

  10. Fumiaki Kohsaka and Wataru Takahashi, Block iterative methods for a finite family of relatively nonexpansive mappings in Banach spaces, Fixed Point Theory and Applications 2007, Article ID 21972 (2007), 1--18.

  11. Fumiaki Kohsaka and Wataru Takahashi, Approximating common fixed points of countable families of strongly nonexpansive mappings, Nonlinear Studies 14, No.2 (2007), 219--234.

  12. Fumiaki Kohsaka and Wataru Takahashi, Generalized nonexpansive retractions and a proximal-type algorithm in Banach spaces, Journal of Nonlinear and Convex Analysis 8, No.2 (2007), 197--209.

  13. Fumiaki Kohsaka and Wataru Takahashi, The set of common fixed points of an infinite family of relatively nonexpansive mappings, Proceedings of the International Symposium on Banach and Function Spaces II, 361--373, 2008.

  14. Fumiaki Kohsaka and Wataru Takahashi, Strongly convergent net given by a fixed point theorem for firmly nonexpansive type mappings, Applied Mathematics and Computation 202, No.2 (2008), 760--765.

  15. Fumiaki Kohsaka and Wataru Takahashi, Fixed point theorems for a class of nonlinear mappings related to maximal monotone operators in Banach spaces, Archiv der Mathematik 91, No.2 (2008), 166--177.

  16. Fumiaki Kohsaka and Wataru Takahashi, Existence and approximation of fixed points of firmly nonexpansive-type mappings in Banach spaces, SIAM Journal on Optimization 19, No.2 (2008), 824--835.

  17. Koji Aoyama, Fumiaki Kohsaka, and Wataru Takahashi, Strong convergence theorems by shrinking and hybrid projection methods for relatively nonexpansive mappings in Banach spaces, Proceedings of the 5th International Conference on Nonlinear Analysis and Convex Analysis, 7--26, 2009.

  18. Koji Aoyama, Fumiaki Kohsaka, and Wataru Takahashi, Three generalizations of firmly nonexpansive mappings: Their relations and continuity properties, Journal of Nonlinear and Convex Analysis 10, No.1 (2009), 131--147.

  19. Koji Aoyama, Fumiaki Kohsaka, and Wataru Takahashi, Strongly relatively nonexpansive sequences in Banach spaces and applications, Journal of Fixed Point Theory and Applications 5, No.2 (2009), 201--225.

  20. Koji Aoyama, Fumiaki Kohsaka, and Wataru Takahashi, Strong convergence theorems for a family of mappings of type (P) and applications, Proceedings of the Asian Conference on Nonlinear Analysis and Optimization, 1--17, 2009.

  21. Fumiaki Kohsaka, Fixed points of semigroups of nonexpansive mappings in compact convex metric spaces, Proceedings of the Asian Conference on Nonlinear Analysis and Optimization, 179--184, 2009.

  22. Koji Aoyama, Fumiaki Kohsaka, and Wataru Takahashi, Shrinking projection methods for firmly nonexpansive mappings, Nonlinear Analysis Series A: Theory, Methods & Applications 71, No.12 (2009), e1626--e1632.

  23. Wataru Takahashi, Jen-Chih Yao, and Fumiaki Kohsaka, The fixed point property and unbounded sets in Banach spaces, Taiwanese Journal of Mathematics 14, No.2 (2010), 733--742.

  24. Koji Aoyama and Fumiaki Kohsaka, Existence of fixed points of firmly nonexpansive-like mappings in Banach spaces, Fixed Point Theory and Applications 2010, Article ID 512751 (2010), 1--15.

  25. Koji Aoyama, Shigeru Iemoto, Fumiaki Kohsaka, and Wataru Takahashi, Fixed point and ergodic theorems for $\lambda$-hybrid mappings in Hilbert spaces, Journal of Nonlinear and Convex Analysis 11, No.2 (2010), 335--343.

  26. Koji Aoyama, Fumiaki Kohsaka, and Wataru Takahashi, Proximal point methods for monotone operators in Banach spaces, Taiwanese Journal of Mathematics 15, No.1 (2011), 259--281.

  27. Koji Aoyama and Fumiaki Kohsaka, Fixed point and mean convergence theorems for a family of $\lambda$-hybrid mappings, Journal of Nonlinear Analysis and Optimization 2, No.1 (2011), 87--95.

  28. Koji Aoyama and Fumiaki Kohsaka, Fixed point theorem for $\alpha$-nonexpansive mappings in Banach spaces, Nonlinear Analysis Series A: Theory, Methods & Applications 74, No.13 (2011), 4387--4391.

  29. Fumiaki Kohsaka, Existence of fixed points of nonspreading mappings with Bregman distances, Proceedings of the International Conference on Nonlinear Mathematics for Uncertainty and its Applications, Advances in Intelligent and Soft Computing 100, 403--410, 2011.

  30. Fumiaki Kohsaka, Minimax problems and mappings of firmly nonexpansive type in Banach spaces, Proceedings of the International Symposium on Banach and Function Spaces III, 381--390, 2011.

  31. Koji Aoyama, Yasunori Kimura, and Fumiaki Kohsaka, Strong convergence theorems for strongly relatively nonexpansive sequences and applications, Journal of Nonlinear Analysis and Optimization 3, No.1 (2012), 67--77.

  32. Koji Aoyama and Fumiaki Kohsaka, Uniform mean convergence theorems for hybrid mappings in Hilbert spaces, Fixed Point Theory and Applications 2012: 193 (2012), 1--13.

  33. Koji Aoyama and Fumiaki Kohsaka, Viscosity approximation process for a sequence of quasinonexpansive mappings, Fixed Point Theory and Applications 2014: 17 (2014), 1--11.

  34. Fumiaki Kohsaka, Averaged sequences for nonspreading mappings in Banach spaces, Proceedings of the International Symposium on Banach and Function Spaces IV, 313--323, 2014.

  35. Koji Aoyama and Fumiaki Kohsaka, Strongly relatively nonexpansive sequences generated by firmly nonexpansive-like mappings, Fixed Point Theory and Applications 2014: 95 (2014), 1--13.

  36. Fumiaki Kohsaka, An implicitly defined iterative sequence for monotone operators in Banach spaces, Journal of Inequalities and Applications 2014: 181 (2014), 1--9.

  37. Fumiaki Kohsaka, Weak convergence theorem for a sequence of quasinonexpansive type mappings, Proceedings of the 8th International Conference on Nonlinear Analysis and Convex Analysis, 289--300, 2015.

  38. Fumiaki Kohsaka, Ray's theorem revisited: a fixed point free firmly nonexpansive mapping in Hilbert spaces, Journal of Inequalities and Applications 2015: 86 (2015), 1--3.

  39. Fumiaki Kohsaka, Existence and approximation of common fixed points of two hybrid mappings in Hilbert spaces, Journal of Nonlinear and Convex Analysis 16, No.11 (2015), 2193--2205.

  40. Yasunori Kimura and Fumiaki Kohsaka, Spherical nonspreadingness of resolvents of convex functions in geodesic spaces, Journal of Fixed Point Theory and Applications 18, No.1 (2016), 93--115 (First online: 31 October 2015).

  41. Yasunori Kimura and Fumiaki Kohsaka, Two modified proximal point algorithms for convex functions in Hadamard spaces, Linear and Nonlinear Analysis 2, No.1 (2016), 69--86.

  42. Fumiaki Kohsaka and Tomonari Suzuki, Existence and approximation of fixed points of Chatterjea mappings with Bregman distances, Linear and Nonlinear Analysis 3, No.1 (2017), 73--86.

  43. Yasunori Kimura and Fumiaki Kohsaka, The proximal point algorithm in geodesic spaces with curvature bounded above, Linear and Nonlinear Analysis 3, No.1 (2017), 133--148.

  44. Koji Aoyama and Fumiaki Kohsaka, Cutter mappings and subgradient projections in Banach spaces, Linear and Nonlinear Analysis 3, No.3 (2017), 457--473.

  45. Fumiaki Kohsaka, Existence and approximation of fixed points of vicinal mappings in geodesic spaces, Pure and Applied Functional Analysis 3, No.1 (2018), 91--106.

  46. Yasunori Kimura and Fumiaki Kohsaka, Two modified proximal point algorithms in geodesic spaces with curvature bounded above, Rendiconti del Circolo Matematico di Palermo Series 2 68, No.1 (2019), 83--104 (First online: 12 April 2018).

  47. Fumiaki Kohsaka, Fixed points of metrically nonspreading mappings in Hadamard spaces, Applied Analysis and Optimization 3, No.2 (2019), 213--230.

  48. Koji Aoyama and Fumiaki Kohsaka, Strongly quasinonexpansive mappings, III, Linear and Nonlinear Analysis 6, No.1 (2020), 1--12.

  49. Parin Chaipunya, Fumiaki Kohsaka, and Poom Kumam, Monotone vector fields and generation of nonexpansive semigroups in complete CAT(0) spaces, Numer. Funct. Anal. Optim. 42, No. 9 (2021), 989--1018. 

  50. Sakan Termkaew, Parin Chaipunya, and Fumiaki Kohsaka, Infinite product and its convergence in CAT(1) spaces, Mathematics, Published online: April 11, 2023.

Oral Presentations

• 1. Fumiaki Kohsaka* and Wataru Takahashi, Approximating zero points of accretive operators in strictly convex Banach spaces, in The Second International Conference on Nonlinear Analysis and Convex Analysis, Hirosaki University, Hirosaki, Japan, July 30--August 2, 2001.

  2. Fumiaki Kohsaka* and Wataru Takahashi, Approximating solutions of maximal monotone operators in a Banach space and applications, in The Third International Conference on Nonlinear Analysis and Convex Analysis, Tokyo Institute of Technology, Tokyo, Japan, August 25--29, 2003.

  3. Fumiaki Kohsaka* and Wataru Takahashi, Minimization theorems in Banach spaces with applications, in The International Symposium on Banach and Function Spaces 2003, Kyushu Institute of Technology, Kitakyushu, Japan, October 2--4, 2003.

  4. Fumiaki Kohsaka* and Wataru Takahashi, Convergence theorems for closed convex sets and maximal monotone operators, in The International Videoconference of Mathematical Sciences, Japanese Association of Mathematical Sciences, Japan, December 2, 2003.

  5. Fumiaki Kohsaka* and Wataru Takahashi, Convergence theorems for maximal monotone operators in Banach spaces, in The Fourth World Congress of Nonlinear Analysts, Hyatt Grand Cypress Resort, Orlando, Florida, USA, June 30--July 7, 2004.

  6. Fumiaki Kohsaka* and Wataru Takahashi, Projection algorithms for families of convex sets in Banach spaces, in The Fourth International Conference on Nonlinear Analysis and Convex Analysis, Okinawa Convention Center, Okinawa, Japan, June 30--July 4, 2005.

  7. Fumiaki Kohsaka* and Wataru Takahashi, Approximating common fixed points of families of relatively nonexpansive mappings in Banach spaces, in The Second International Symposium on Banach and Function Spaces 2006, Kyushu Institute of Technology, Kitakyushu, Japan, September 14--17, 2006.

  8. Fumiaki Kohsaka, Some properties of firmly nonexpansive type mappings in Banach spaces, in The Fifth International Conference on Nonlinear Analysis and Convex Analysis, National Tsing Hua University, Hsinchu, Taiwan, May 30--June 4, 2007.

  9. Fumiaki Kohsaka, Common fixed points of an infinite family of relatively nonexpansive mappings in Banach spaces, in The Japan-Thailand Joint Seminar on Fixed Point Algorithms in Optimization, Tokyo Institute of Technology, Tokyo, Japan, September 6--7, 2007.

  10. Fumiaki Kohsaka, On fixed points of firmly nonexpansive type mappings in Banach spaces, in The Fifth World Congress of Nonlinear Analysts, Hyatt Grand Cypress Resort, Orlando, Florida, USA, July 2--9, 2008.

  11. Fumiaki Kohsaka, Fixed points of nonspreading mappings in Banach spaces, in Asian Conference on Nonlinear Analysis and Optimization, Kunibiki Messe, Matsue, Shimane, Japan, September 14--18, 2008.

  12. Fumiaki Kohsaka, The set of common fixed points of families of relatively nonexpansive mappings, in The Sixth International Conference on Nonlinear Analysis and Convex Analysis, Tokyo Institute of Technology, Tokyo, Japan, March 27--31, 2009.

  13. Fumiaki Kohsaka, Maximal monotone operators and firmly nonexpansive-type mappings in Banach spaces, in The 9th International Conference on Fixed Point Theory and Its Applications, National Changhua University of Education, Changhua, Taiwan, July 16--22, 2009.

  14. Fumiaki Kohsaka, Fixed point theorems for mappings of type (P), (Q), and (R) in Banach spaces, in The Third International Symposium on Banach and Function Spaces 2009, Kyushu Institute of Technology, Kitakyushu, Japan, September 14--17, 2009.

  15. Fumiaki Kohsaka, On fixed points of firmly nonexpansive-like mappings in Banach spaces, in The Second Asian Conference on Nonlinear Analysis and Optimization, Royal Paradise Hotel & Spa, Patong Beach, Phuket, Thailand, September 9--12, 2010.

  16. Fumiaki Kohsaka, Existence of fixed points of nonspreading mappings with Bregman distances, in The International Conference on Nonlinear Mathematics for Uncertainty and its Applications, Beijing University of Technology, Beijing, China, September 7--9, 2011.

  17. Fumiaki Kohsaka, Some properties of resolvents of monotone operators in Banach spaces, in The Third Asian Conference on Nonlinear Analysis and Optimization, Kunibiki Messe, Matsue, Shimane, Japan, September 2--6, 2012.

  18. Fumiaki Kohsaka, Fixed point theorems for some nonlinear mappings related to resolvents of monotone or accretive operators, in The Fourth International Symposium on Banach and Function Spaces 2012, Kyushu Institute of Technology, Kitakyushu, Japan, September 12--15, 2012.

  19. Fumiaki Kohsaka, Modified proximal point methods for monotone operators in Banach spaces, in The International Conference on the Theory, Methods and Applications of Nonlinear Equations, Texas A&M University-Kingsville, Texas, USA, December 17--21, 2012.

  20. Fumiaki Kohsaka, Unbounded sets and nonexistence of fixed points in Banach spaces, in The International Conference Anatolian Communications in Nonlinear Analysis, Abant Izzet Baysal University, Bolu, Turkey, July 3--6, 2013.

  21. Fumiaki Kohsaka, On firmly nonexpansive type mappings in Banach spaces, in The Eighth International Conference on Nonlinear Analysis and Convex Analysis, Hirosaki University, Hirosaki, Japan, August 2--6, 2013.

  22. Fumiaki Kohsaka, Strong convergence theorem for a strongly relatively nonexpansive sequence of mappings, in The International Conference on Nonlinear Analysis and Optimization, National Sun Yat-sen University, Kaohsiung, Taiwan, December 20--22, 2013.

  23. Fumiaki Kohsaka, Finding fixed points of firmly nonexpansive-like mappings in Banach spaces, in The International Congress in Honour of Professor Ravi P. Agarwal, Uludag University, Bursa, Turkey, June 23--26, 2014.

  24. Fumiaki Kohsaka, Mean convergence theorems for pointwise convergent sequences of hybrid mappings, in The Ninth International Conference on Nonlinear Analysis and Convex Analysis, Rimkok Resort Hotel, Chiang Rai, Thailand, January 21--25, 2015.

  25. Fumiaki Kohsaka, Asymptotic behavior of averaged sequences for nonspreading mappings in Banach spaces, in The Fifth International Symposium on Banach and Function Spaces 2015, Kyushu Institute of Technology, Kitakyushu, Japan, September 2--6, 2015.

  26. Fumiaki Kohsaka, An implicitly defined iterative sequence for maximal monotone operators in Banach spaces, in VII Symposium on Nonlinear Analysis, Nicolaus Copernicus University, Torun, Poland, September 14--18, 2015.

  27. Fumiaki Kohsaka, Existence and approximation of minimizers of convex functions in geodesic metric spaces, in The 9th Asian Conference on Fixed Point Theory and Optimization, King Mongkut's University of Technology Thonburi, Bangkok, Thailand, May 18--20, 2016.

  28. Fumiaki Kohsaka, Spherically nonspreading mappings in geodesic metric spaces with curvature bounded above, in The 5th Asian Conference on Nonlinear Analysis and Optimization, Toki Messe, Niigata, Japan, August 1--6, 2016.

  29. Fumiaki Kohsaka, Minimizing convex functions in geodesic metric spaces with curvature bounded above, in The International Conference on New Trends in Optimization and Variational Analysis for Applications, Quy Nhon University, Quy Nhon, Vietnam, December 7--10, 2016.

  30. Fumiaki Kohsaka, The proximal point algorithm and its variants for convex functions in geodesic metric spaces, in The 10th Anniversary International Conference on Nonlinear Analysis and Convex Analysis, Chitose City Cultural Center, Chitose, Japan, July 4--9, 2017.

  31. Fumiaki Kohsaka, Approximating minimizers of convex functions in geodesic metric spaces with curvature bounded above, in XII International Symposium on Generalized Convexity and Monotonicity, Hajduszoboszlo, Hungary, August 27--September 2, 2017.

  32. Fumiaki Kohsaka, The resolvents of convex functions in geodesic metric spaces, in The Workshop Convex Analysis in CAT(k) Spaces, King Mongkut's University of Technology Thonburi, Bangkok, Thailand, September 8--9, 2017.

  33. Fumiaki Kohsaka, Fixed point problems for spherically nonspreading mappings and vicinal mappings in CAT(1) spaces, in The Workshop Convex Analysis in CAT(k) Spaces, King Mongkut's University of Technology Thonburi, Bangkok, Thailand, September 8--9, 2017.

  34. Fumiaki Kohsaka, The proximal point algorithm for convex functions in geodesic spaces, in A seminar on Nonlinear Analysis and Applications, Tokai University, Hiratsuka, Japan, April 4, 2018.

  35. Fumiaki Kohsaka, Fixed points of vicinal mappings in complete CAT(1) spaces, in The 10th Asian Conference on Fixed Point Theory and Optimization, The Empress Hotel, Chiang Mai, Thailand, July 16--18, 2018.

  36. Fumiaki Kohsaka, Recent results on the resolvents of convex functions in geodesic spaces, in The Inthernational Symposium on Nonlinear Convex Analysis and Optimization 2018, King Mongkut's University of Technology Thonburi, Bangkok, Thailand, July 19--22, 2018.

  37. Fumiaki Kohsaka, Fixed points of vicinal mappings and convex optimization in geodesic metric spaces, in The Inthernational Workshop on Variational Analysis and Applications, Ettore Majorana Foundation and Centre for Scientific Culture, Erice--Sicily, Italy, August 28--September 5, 2018.

  38. Fumiaki Kohsaka, Fixed points of nonspreading mappings and its relatives in Banach spaces, in The Seminar on Fixed Point Theory and Optimization, Khon Kaen University, Khon Kaen, Thailand, September 12, 2018.

  39. Fumiaki Kohsaka, Fundamental properties of resolvents of convex functions in geodesic spaces, in The Seminar on Fixed Point Theory and Optimization, Khon Kaen University, Khon Kaen, Thailand, September 12, 2018.

  40. Fumiaki Kohsaka, Fixed points of Chatterjea mappings with Bregman distances in Banach spaces, in The 6th Asian Conference on Nonlinear Analysis and Optimization, Okinawa Institute of Science and Technology Graduate University and ANA Intercontinental Manza Beach Resort, Onna-son, Okinawa, Japan, November 5--9, 2018.

  41. Pinya Ardsalee, Fumiaki Kohsaka, Jenjira Puiwong, and Satit Saejung*, On metric completeness and some preservations of convex metric spaces in the sense of Takahashi, in International Conference on Nonlinear Analysis and Convex Analysis--International Conference on Optimization: Techniques and Applications (NACA-ICOTA2019), Future University Hakodate, Hakodate, Japan, August 26--31, 2019.

  42. Fumiaki Kohsaka, Fixed points of metrically nonspreading mappings in Hadamard spaces, in International Conference on Nonlinear Analysis and Convex Analysis--International Conference on Optimization: Techniques and Applications (NACA-ICOTA2019), Future University Hakodate, Hakodate, Japan, August 26--31, 2019.

  43. Fumiaki Kohsaka, Finding fixed points of metrically nonspreading mappings in Hadamard spaces, in The 2nd International Workshop on Applied Nonlinear Analysis (IWANA2019), Bangsaen, Chonburi, Thailand, September 12--14, 2019.

  44. Fumiaki Kohsaka, Firmly nonexpansive like mappings in Banach spaces, in Workshop on "Convex Analysis on Geodesic Spaces", Khon Kaen University, Khon Kaen, Thailand, September 17--18, 2019.

  45. Fumiaki Kohsaka, Metrically nonspreading mappings, in Workshop on "Convex Analysis on Geodesic Spaces", Khon Kaen University, Khon Kaen, Thailand, September 17--18, 2019.

  46. Fumiaki Kohsaka, Fixed point problems for firmly nonexpansive like mappings in Banach spaces, in 14th International Seminar on Optimization and Related Areas (ISORA), the Instituto de Matemática y Ciencias Afines (IMCA), Lima, Peru, October 7--11, 2019.

Theses

• 1. Fumiaki Kohsaka, An integration property of subdifferential mappings and minimization theorems on Banach spaces, Master Thesis (Tokyo Institute of Technology, March/2001), supervised by Prof. Dr. Wataru Takahashi.

  2. Fumiaki Kohsaka, Convergence theorems and minimization theorems for nonlinear operators in Banach spaces, Docter Thesis (Tokyo Institute of Technology March/2004), supervised by Prof. Dr. Wataru Takahashi.

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