Free ℤ-module
Futa, Yuichi, Okazaki, Hiroyuki, Shidama, Yasunari
Cell Petri Net Concepts
Jitsukawa, Mitsuru, Kawamoto, Pauline, Shidama, Yasunari, Nakamura, Yatsuka
Real Vector Space and Related Notions
Nakasho, Kazuhisa, Okazaki, Hiroyuki, Shidama, Yasunari