The Jordan curve theorem and the Schönflies theorem in weak second-order arithmetic. - Nobuyuki Sakamoto; Keita Yokoyama (Arch. Math. Log., 2007)

Complex analysis in subsystems of second order arithmetic. - Keita Yokoyama (Arch. Math. Log., 2007)

Non-standard analysis in ACA0 and Riemann mapping theorem. - Keita Yokoyama (Math. Log. Q., 2007)

Formalizing non-standard arguments in second-order arithmetic. - Keita Yokoyama (J. Symb. Log., 2010)

A Nonstandard Counterpart of WWKL. - Stephen G. Simpson; Keita Yokoyama (Notre Dame J. Formal Log., 2011)

The Dirac delta function in two settings of Reverse Mathematics. - Sam Sanders; Keita Yokoyama (Arch. Math. Log., 2012)

A Note on the Sequential Version of Statements. - Makoto Fujiwara; Keita Yokoyama (CiE, 2013)

Reverse mathematics and Peano categoricity. - Stephen G. Simpson; Keita Yokoyama (Ann. Pure Appl. Log., 2013)

On the strength of Ramsey's theorem without Σ1-induction. - Keita Yokoyama (Math. Log. Q., 2013)

On the Ramseyan Factorization Theorem. - Shota Murakami; Takeshi Yamazaki; Keita Yokoyama (CiE, 2014)

Propagation of partial randomness. - Kojiro Higuchi; W. M. Phillip Hudelson; Stephen G. Simpson; Keita Yokoyama (Ann. Pure Appl. Log., 2014)

Nonstandard second-order arithmetic and Riemann's mapping theorem. - Yoshihiro Horihata; Keita Yokoyama (Ann. Pure Appl. Log., 2014)

Categorical characterizations of the natural numbers require primitive recursion. - Leszek Aleksander Kolodziejczyk; Keita Yokoyama (Ann. Pure Appl. Log., 2015)

Reverse mathematical bounds for the Termination Theorem. - Silvia Steila; Keita Yokoyama (Ann. Pure Appl. Log., 2016)

On principles between ∑1- and ∑2-induction, and monotone enumerations. - Alexander P. Kreuzer; Keita Yokoyama (J. Math. Log., 2016)

The Strength of the SCT Criterion. - Emanuele Frittaion; Silvia Steila; Keita Yokoyama (TAMC, 2017)

A parameterized halting problem, the linear time hierarchy, and the MRDP theorem. - Yijia Chen 001; Moritz Müller; Keita Yokoyama (LICS, 2018)

The strength of Ramsey's Theorem for Pairs and arbitrarily Many Colors. - Theodore A. Slaman; Keita Yokoyama (J. Symb. Log., 2018)

The strength of SCT soundness. - Emanuele Frittaion; Florian Pelupessy; Silvia Steila; Keita Yokoyama (J. Log. Comput., 2018)

Leveraging an Efficient and Semantic Location Embedding to Seek New Ports of Bike Share Services. - Yuan Wang 076; Chenwei Wang 001; Yinan Ling; Keita Yokoyama; Hsin-Tai Wu; Yi Fang 008 (IEEE BigData, 2020)

Combinatorial principles equivalent to weak induction. - Caleb Davis; Denis R. Hirschfeldt; Jeffry L. Hirst; Jake Pardo; Arno Pauly; Keita Yokoyama (Comput., 2020)

In Search of the First-Order Part of Ramsey's Theorem for Pairs. - Leszek Aleksander Kolodziejczyk; Keita Yokoyama (CiE, 2021)

Karaoke Key Recommendation Via Personalized Competence-Based Rating Prediction. - Yuan Wang 076; Shigeki Tanaka; Keita Yokoyama; Hsin-Tai Wu; Yi Fang 008 (ICASSP, 2021)

Memory Efficient Adversarial Attacks on Graphs: A Winning Solution for KDD Cup 2020. - Keiichi Ochiai; Takuya Chida; Keita Yokoyama; Daisuke Koizumi; Hiroaki Tanaka; Akihiro Kawana (ICMU, 2021)

The Reverse Mathematics of theorems of Jordan and Lebesgue. - André Nies; Marcus Anthony Triplett; Keita Yokoyama (J. Symb. Log., 2021)

Two-sided Rank Consistent Ordinal Regression for Interpretable Music Key Recommendation. - Yuan Wang 076; Shigeki Tanaka; Keita Yokoyama; Hsin-Tai Wu; Yi Fang 008 (ICTIR, 2022)

A parameterized halting problem, Δ0 truth and the MRDP theorem. - Yijia Chen 001; Moritz Müller; Keita Yokoyama (CoRR, 2022)

How Strong is Ramsey's Theorem if infinity can be Weak? - Leszek Aleksander Kolodziejczyk; Katarzyna W. Kowalik; Keita Yokoyama (J. Symb. Log., 2023)

Extended Frames and Separations of Logical Principles. - Makoto Fujiwara; Hajime Ishihara; Takako Nemoto; Nobu-Yuki Suzuki; Keita Yokoyama (Bull. Symb. Log., 2023)

Searching problems above arithmetical transfinite recursion. - Yudai Suzuki; Keita Yokoyama (Ann. Pure Appl. Log., 2024)

On the first-order parts of problems in the Weihrauch degrees. - Damir D. Dzhafarov; Reed Solomon; Keita Yokoyama (Comput., 2024)

Ramsey's theorem for pairs, collection, and proof size. - Leszek Aleksander Kolodziejczyk; Tin Lok Wong; Keita Yokoyama (J. Math. Log., 2024)

Completeness Theorems for Modal Logic in Second-Order Arithmetic. - Sho Shimomichi; Yuto Takeda; Keita Yokoyama (CiE, 2025)

A Parameterized Halting Problem, $ Delta _0$ Truth and the Mrdp Theorem. - Yijia Chen 001; Moritz Müller; Keita Yokoyama (J. Symb. Log., 2025)