A Coalgebraic Representation of Reduction by Cone of Influence. - Hiroshi Watanabe; Koki Nishizawa; Osamu Takaki (CMCS, 2006)

A Non-probabilistic Relational Model of Probabilistic Kleene Algebras. - Hitoshi Furusawa; Norihiro Tsumagari; Koki Nishizawa (RelMiCS, 2008)

The Cube of Kleene Algebras and the Triangular Prism of Multirelations. - Koki Nishizawa; Norihiro Tsumagari; Hitoshi Furusawa (RelMiCS, 2009)

Multi-Valued Modal Fixed Point Logics for Model Checking. - Koki Nishizawa (IEICE Trans. Inf. Syst., 2010)

Modal μ-calculus on Min-plus Algebra N∞. - Dai Ikarashi; Yoshinori Tanabe; Koki Nishizawa; Masami Hagiya (Inf. Media Technol., 2010)

An Algebraic Semantics of Predicate Abstraction for PML. - Yoshiki Kinoshita; Koki Nishizawa (Inf. Media Technol., 2010)

Relational and Multirelational Representation Theorems for Complete Idempotent Left Semirings. - Hitoshi Furusawa; Koki Nishizawa (RAMiCS, 2011)

Relational Representation Theorem for Powerset Quantales. - Koki Nishizawa; Hitoshi Furusawa (RAMiCS, 2012)

Implementation of high-definition lecture recording system for daily use. - Takayuki Nagai; Toshiyuki Toyota; Takayuki Nagoya; Koki Nishizawa; Masakazu Imai (EDUCON, 2013)

A Sufficient Condition for Liftable Adjunctions between Eilenberg-Moore Categories. - Koki Nishizawa; Hitoshi Furusawa (RAMiCS, 2014)

Multirelational representation theorems for complete idempotent left semirings. - Hitoshi Furusawa; Koki Nishizawa (J. Log. Algebraic Methods Program., 2015)

Composition of Different-Type Relations via the Kleisli Category for the Continuation Monad. - Koki Nishizawa; Norihiro Tsumagari (RAMiCS, 2018)

Preorders, Partial Semigroups, and Quantales. - Koki Nishizawa; Koji Yasuda; Hitoshi Furusawa (RAMiCS, 2020)

Stone dualities from opfibrations. - Koki Nishizawa; Shin-ya Katsumata; Yuichi Komorida (J. Log. Algebraic Methods Program., 2022)

Categorical generalization of spectral decomposition. - Koki Nishizawa; Yusuke Ide; Norihiro Tsumagari (CoRR, 2025)