Sequent Calculi for Visser's Propositional Logics. - Katsumasa Ishii; Ryo Kashima; Kentaro Kikuchi (Notre Dame J. Formal Log., 2001)

A note on the first incompleteness theorem. - Katsumasa Ishii (Math. Log. Q., 2003)

New sequent calculi for Visser's Formal Propositional Logic. - Katsumasa Ishii (Math. Log. Q., 2003)

A note on decidability of variables in intuitionistic propositional logic. - Katsumasa Ishii (Math. Log. Q., 2018)

A proof of the leftmost reduction theorem for λβη-calculus. - Katsumasa Ishii (Theor. Comput. Sci., 2018)

A Sufficient Condition for a Prime to be a Sophie Germain Prime. - Katsumasa Ishii (Am. Math. Mon., 2024)

On Harrop disjunction property in intermediate predicate logics. - Katsumasa Ishii (Arch. Math. Log., 2024)