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Keita Yokoyama Senior Lecturer
School of Information Science¡¢Intelligent Robotics Area


B.S.from Tokyo Institute of Technology(2004), M.S.from Tohoku University(2005), Ph.D from Tohoku University(2008)

¢£Professional Career

Research Assistant at Tohoku University(2005), JSPS Research Fellow at Tohoku University(DC2)(2006), Assistant of Educational Service at Tokyo Institute of Technology(2008), Assistant Professor at Tohoku University(2008), Part-time Lecturer at Yamagata University(2009), Assistant Professor at Tohoku University(2010), Visiting Postdoc of Pennsylvania State University(2011), JSPS Research Fellow at Tokyo Institute of Technology(PD)(2011)


Mathematical Logic

¢£Research Keywords

Proof theory, first and second-order arithmetic, reverse mathematics, nonstandard analysis

¢£Research Interests

Reverse mathematics by using nonstandard models of arithmetic
My research is aimed at developing connections between some techniques of models or arithmetic with reverse mathematics.


¡þPublished Papers

  • Recent studies on the proof-theoretic strength of Ramsey's theorem for pairs¡¤Keita Yokoyama¡¤in RIMS Kokyuroku 2050; Makoto Kikuchi (ed.): Mathematical Logic and Its Applications, pages 67-76, October, 2017
  • A parameterized halting problem, the linear time hierarchy, and the MRDP theorem¡¤Yijia Chen, Moritz Mu ̈ller and Keita Yokoyama¡¤Proceedings of the 33rd Annual ACM/IEEE Symposium on Logic in Computer Science, 2018, pages: 235-244
  • The proof-theoretic strength of Ramsey's theorem for pairs and two colors¡¤Ludovic Patey and Keita Yokoyama¡¤Advances in Mathematics 330, pages: 1034-1070, 2018

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¡þLectures and Presentations

  • Reverse mathematics and termination analysis¡¤Keita Yokoyama¡¤14th Asian Logic Conference, IIT Bombay, India, January 5-8, 2015
  • Proof transformations for nonstandard analysis¡¤Keita Yokoyama¡¤The 10th AIMS Conference on Dynamical Systems, Differential Equations and Applications, Special session 114: Nonstandard Analysis, Quantizations and Singular Perturbations¡¤Madrid, Spain¡¤2014/07/07-11
  • Termination theorem and Ramsey's theorem¡¤Keita Yokoyama¡¤IMS-JSPS Joint Workshop in Mathematical Logic and Foundations of Mathematics¡¤National University of Sigapore¡¤September 1-5, 2014

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¢£Extramural Activities

¡þAcademic Society Affiliations

  • Association for Symbolic Logic¡¤2008-