Koichi Nagano

CAT(0) 4-manifolds are Euclidean

Stephan Stadler, Alexander Lytchak, Koichi Nagano, 2021, 2109.09438.

Two-dimensional metric spaces with curvature bounded above I

Takao Yamaguchi, Koichi Nagano, Takashi Shioya, 2021 .

Asymptotic topological regularity of CAT(0) spaces

Koichi Nagano, Koichi Nagano, 2021, Annals of Global Analysis and Geometry.

Fixed point sets of parabolic isometries of CAT(0)-spaces

Koji Fujiwara, Koichi Nagano, Takashi Shioya, 2004 .