Satisfiability of 3CNF formulas with small clause/variable-ratio. - Kazuo Iwama; Kazuya Takaki (Satisfiability Problem: Theory and Applications, 1996)

Tight Bounds on the Number of States of DFA's That Are Equivalent to n-state NFA's. - Kazuo Iwama; Kazuya Takaki (Developments in Language Theory, 1997)

Tight bounds on the number of states of DFAs that are equivalent to n-state NFAs. - Kazuo Iwama; Yahiko Kambayashi; Kazuya Takaki (Theor. Comput. Sci., 2000)