・計算機を用いた精度保証付き数値計算

・行列における多重固有値、近接固有値の高精度判定

・マルコフ決定過程 　

1 Numerical enclosure for multiple eigenvalues of an Hermitian matrix whose graph is a tree. Kenji Toyonaga, Linear Algebra and Its Applications, 431 (2009), pp. 1989-1999. 　 　 　 　 　 　

2 A method for seperating nearly multiple eigenvalues for Hermitian matrix
Kenji Toyonaga, Journal of Computational and Applied Mathematics ,
Vol.199.2, 432-436, 2007

3　Equivalence classes for optimizing risk models in Markov decision processes,
Yoshio Ohtsubo, Kenji Toyonaga, Mathematical Methods of Operations Research
60, 239-250, 2004

4 Verified numerical computations for multiple or nearly multiple eigenvalues for elliptic 　 　 operators, K.Toyonaga, M.T.Nakao, Y.Watanabe, Journal of Computational and Applied 　 　 Mathematics, 147, 175-190, 2002

5 Optimal Policy for Minimizing Risk Models in Markov Decision Processes
Y.Ohtsubo, K.Toyonag Journal of Mathematical Analysis and Applications,271, 66-81

6 Numerical Enclosure for the Optimal Threshold Probability in Discounted Markov 　 　 Decision Processes, Kenji Toyonaga and Mitsuhiro T.Nakao, Bulletin of Informatics and Cybernetics, 32, 81-90, 2000