Last updated: 2025/09/21
Last updated: 2025/09/21
Ryo Uchiumi (内海 凌 / うちうみ りょう)
Affiliation: The University of Osaka, Department of Mathematics, Graduate School of Science, Japan (Ph.D student)
NEWS (yyyy/mm/dd)
(2025/08/15) : Preprint The characteristic quasi-polynomials of hyperplane arrangements with actions of finite groups.
(2025/09/12) : Talked at Mini-Workshop on Discrete Mathematics and Related Topics (Waseda Uhiversity).
(2025/09/17) : Talked at MSJ Autumn Meeting 2025 at Nagoya University.
Finite reflection groups, Root systems
Graphs
Group actions, Combinatorial representations
Hyperplane arrangements (characteristic (quasi-)polynomial / freeness)
Bachelor (Education): Hokkaido Univ. of Education, Asahikawa, Department of Mathematics Education. (2018/04/01 ~ 2022/03/15)
Bachelor's Thesis (survey, informal): 有限鏡映群と図形の対称性．
Master (Science): Hokkaido Univ. Department of Mathematics, Graduate School of Science. (2022/04/01 ~ 2024/03/25)
Master's Thesis: The product of transpositions associated with labeled edges of the graph.
Doctor (Science): The University of Osaka Department of Mathematics, Graduate School of Science. (2024/04/01 ~ )
If you would like to read my theses, please contact me below.
Peer-reviewed
R. Uchiumi, Signed graphs and signed cycles of hyperoctahedral groups. Electronic Journal of Graph Theory and Applications (EJGTA) 11 (2023), no. 2, 419--429. (arXiv: 2211.05475)
S. Tsujie and R. Uchiumi, Upper Embeddability of Graphs and Products of Transpositions Associated with Edges. Ars Mathematica Contemporanea 25 (2025), no. 2, #P2.05. (arXiv: 2211.05422)
(Conference paper) T. Nian, S. Tsujie, R. Uchiumi and M. Yoshinaga, q-Deformation of Graphical Arrangements. Séminaire Lotharingien de Combinatoire 93B 149 (2025)
(Conference paper) R. Uchiumi, Permutation Representations of Classical Weyl Groups on mod q Lattices. Séminaire Lotharingien de Combinatoire 93B 156 (2025)
Preprints (other than the above)
R. Uchiumi and M. Yoshinaga, The quasi-polynomiality of mod q permutation representation for a linear finite group action on a lattice. (arXiv: 2409.01084)
T. Nian, S. Tsujie, R. Uchiumi and M. Yoshinaga, q-deformation of chromatic polynomials and graphical arrangements. (arXiv: 2412.08290)
S. Tsujie and R. Uchiumi, Exponents of 2-multiarrangements of three lines over fields of positive characteristic. (arXiv: 2506.07070)
R. Uchiumi, The characteristic quasi-polynomials of hyperplane arrangements with actions of finite groups. (arXiv: 2508.10236)
Non-peer-reviewed
(Kôkyûroku, lecture note written in JPN) 内海 凌, 格子への線形な有限群作用におけるmod $q$置換表現の準多項式性について．組合せ論的表現論の発展 Developments in combinatorial representation theory (RIMS)．
辻栄周平*，内海 凌，グラフ埋め込みと辺に付随する互換の積，日本数学会 2023 年度年会 (中央大学)， 2023/03/15．
^ 内海 凌，符号つきグラフの辺に付随する超八面体群の互換の積，Order Seminar (大阪大学)，2023/06/02．
^ 内海 凌，グラフの彩色多項式と超平面配置の特性多項式，組合せ論的ホッジ理論勉強会 (第0回) (大阪大学)，2023/09/26．
^ 内海 凌，グラフのラベル付き辺に付随した互換の積，第2回旭川離散数学セミナー (北海道教育大学旭川校)，2024/02/29．
内海 凌，グラフのラベル付き辺に付随した互換の積，第20回数学総合若手研究集会 (北海道大学)，2024/03/05．
^ 内海 凌，グラフ理論と超平面配置からみる組合せ論，What is ... ? セミナー(第4回) (大阪大学) ，2024/05/23．
^ 内海 凌，格子への線形な有限群作用における mod q 置換表現の準多項式性について，JCCA-DMIA-2024 (山形大学) ，2024/08/21．
^ Ryo Uchiumi，Exponents of multiarrangements of three lines over a field of positive characteristic，Bundles and lattices (Osaka Univ.) ，2024/08/25.
内海 凌*，吉永正彦，格子への線形な有限群作用における mod q 置換表現の準多項式性について，日本数学会 2024 年度秋季総合分科会 (大阪大学) ，2024/09/04．
内海 凌，格子への線形な有限群作用における mod q 置換表現の準多項式性について，RIMS共同研究（公開型）組合せ論的表現論の発展 ，2024/10/16．
^ Ryo Uchiumi*, Masahiko Yoshinaga， A linear finite group action on a lattice and mod q permutation representation (Talk and Poster)，Joint meeting of the NZMS, AustMS and AMS (University of Auckland)，2024/12/13．
内海 凌，格子への線形な有限群作用と mod q 置換表現，第21回数学総合若手研究集会 (北海道大学)，2025/03/03．
Ryo Uchiumi，mod q permutation representations for a linear group action on a lattice，Waseda Workshop on Discrete Mathematics and Related Topics 2025，2025/03/17．
内海 凌，古典型 Weyl 群の格子への作用の mod q 置換表現，日本数学会 2025 年度年会 (早稲田大学)，2025/03/20．
内海 凌，正標数における2次元空間の3本の直線からなる多重配置の指数，Arrangement Days in Osaka (大阪大学)，2025/03/24．
^ 内海 凌，正標数における2次元空間の3本の直線からなる多重配置の指数と基底，Arrangement Days in NITech (名古屋工業大学)，2025/06/12．
^ Ryo Uchiumi，Permutation representation of classical Weyl groups on mod q lattices (Poster)，International Conference on Formal Power Series and Algebraic Combinatorics (FPSAC) 2025 (Hokkaido University)，2025/07/21．
^ Tongyu Nian*, Shuhei Tsujie, Ryo Uchiumi and Masahiko Yoshinaga，q-deformation of graphic arrangement (Poster)，International Conference on Formal Power Series and Algebraic Combinatorics (FPSAC) 2025 (Hokkaido University)，2025/07/22．
内海 凌，有限群が作用する超平面配置の特性準多項式，JCCA-DMIA-2025 (広島)，2025/08/19．
^ Ryo Uchiumi，The characteristic quasi-polynomials of hyperplane arrangements with actions of finite groups，Mini-Workshop on Discrete Mathematics and Related Topics (Waseda Uhiversity)，2025/09/12．
辻栄周平，内海 凌*，正標数における2次元空間の3本の直線からなる多重配置について，日本数学会 2025年度秋季総合分科会 (名古屋大学)，2025/09/17．
【TBS】内海 凌，有限群が作用する超平面配置とその特性準多項式，RIMS共同研究（公開型）合流する組み合わせ論と表現論 (京都大学)，2025/10/23．
* : Speaker，^ : Invited or peer-reviewed
Arrangement Days in Osaka (大阪大学)，2025/03/24 ~ 2025/03/26．
What is ... ? セミナー (大阪大学)，2025/04 ~．
Arrangements in Osaka 2025 (The University of Osaka)，2025/12/15 ~ 2025/12/19．
Mail : ryo.uchiumi.math <atmark> gmail.com, uchiumi.ryou.1xu <atmark> ecs.osaka-u.ac.jp
ORCiD : 0000-0002-4956-7177
Scopus Author ID : 57988765700
Toyonaka-neighbor-food-place (writing in both En & Jp)