九州大学 研究者情報
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基本情報 研究活動 教育活動 社会活動
角 俊雄(すみ としお) データ更新日:2020.06.08



主な研究テーマ
ねじれアレキサンダー多項式を用いた結び目(群)の分類について
キーワード:2次元リボン2結び目、ねじれアレキサンダー多項式
2018.02.
Borsuk-Ulam 群について
キーワード:表現空間
2017.10.
高次元テンソルの複数典型ランクと正則多重線形写像の存在の関係について
キーワード:典型ランク
2014.01.
高次元テンソルの階数について
キーワード:テンソル、階数、典型階数
2008.07.
2固定点作用をもつ球面上の有限群作用と群の表現の関係について
キーワード:群作用、球面、接表現
2006.08.
研究業績
主要著書
1. Toshio Sumi, Toshio Sakata, Mitsuhiro Miyazaki, Algebraic and Computational Aspects of Real Tensor Ranks, Springer, SpringerBriefs in Statistics, 2016.03, Recently, multi-way data or tensor data have been employed in various applied fields. We consider the decomposition of a tensor datum into a sum of rank-1 tensors, where rank-1 tensors are considered to be the simplest tensors. The minimal length of the rank-1 tensors in the sum is called the rank of the tensor. The objective of rank determination is to answer the question, “How many rank-1 tensors are required to express the given tensor?” In this book, we focus on the rank over the real number field R, which is particularly interesting for statisticians..
主要原著論文
1. Taizo Kanenobu, Toshio Sumi, Classification of ribbon 2-knots presented by virtual arcs with up to four crossings, Journal of Knot Theory and Its Ramifications, http://dx.doi.org/10.1142/S0218216519500676, 28, 10, 1950067 (18 pages), 2019.10.
2. Taizo Kanenobu, Toshio Sumi, Twisted Alexander polynomial of a ribbon 2-knot of 1-fusion, Osaka Journal of Mathematics, 2019.05, [URL].
3. Toshio Sumi, Mitsuhiro Miyazaki, Toshio Sakata, Typical ranks of semi-tall real 3-tensors, Linear and Multilinear Algebra, 10.1080/03081087.2019.1637811, 2019.07.
4. Taizo Kanenobu, Toshio Sumi, Classification of a family of ribbon 2-knots with trivial Alexander polynomial, Communications of the Korean Mathematical Society, http://doi.org/10.4134/CKMS.c170222, 33, 2, 591-604, 2018.04.
5. Mitsuhiro Miyazaki, Toshio Sumi, Toshio Sakata, Typical ranks of certain 3-tensors and absolutely full column rank tensors, Linear and Multilinear Algebra, http://www.tandfonline.com/doi/abs/10.1080/03081087.2017.1292994, 66, 1, 193-205, 2017.03, In this paper, we study typical ranks of 3-tensors and show that there are plural typical ranks for m x n x p tensors over the real number field in the following cases: (1) 3≦m≦h(n) and (m-1)(n-1)+1≦p≦(m-1)n, where h is the Hurwitz-Radon function, (2) m=3, n=3 (mod 4) and p=2n-1, (3) m=4, n=2 (mod 4), n≧6 and p=3n-2, (4) m=6, n=4 (mod 8), n≧12 and p=5n-4, (5) m=10, n=24 (mod 32) and p=9n-8..
6. Toshio Sumi, Mitsuhiro Miyazaki, Toshio Sakata, Typical ranks for 3-tensors, nonsingular bilinear maps and determinantal ideals, Journal of Algebra, http://dx.doi.org/10.1016/j.jalgebra.2016.09.028, 471, 1, 409-453, 2017.02, Let m,n≥3, (m−1)(n−1)+2≤p≤mn, and u=mn−p. The set Ru×n×m of all real tensors with size u×n×m is one to one corresponding to the set of bilinear maps Rm×Rn→Ru. We show that Rm×n×p has plural typical ranks p and p+1 if and only if there exists a nonsingular bilinear map Rm×Rn→Ru. We show that there is a dense open subset O of Ru×n×m such that for any Y∈O, the ideal of maximal minors of a matrix defined by Y in a certain way is a prime ideal and the real radical of that is the irrelevant maximal ideal if that is not a real prime ideal. Further, we show that there is a dense open subset T of Rn×p×m and continuous surjective open maps ν:O→Ru×p and σ:T→Ru×p, where Ru×p is the set of u×p matrices with entries in R, such that if ν(Y)=σ(T), then rank T=p if and only if the ideal of maximal minors of the matrix defined by Y is a real prime ideal..
7. Toshio Sumi, Richness of Smith equivalent modules for finite gap Oliver groups, Tohoku Journal of Mathematics, doi:10.2748/tmj/1474652268, 68, 3, 457-469, 2016.09.
8. Toshio Sumi, Mitsuhiro Miyazaki, Toshio Sakata, Typical rank of mxnx(m-1)n tensors with 3<=m<=n over the real number field, Linear and Multilinear Algebra, http://dx.doi.org/10.1080/03081087.2014.910206, 63, 5, 940-955, 2015.07, Let 3<=m<=n. We study typical ranks of m x n x (m-1)n tensors over the real number field. Let be the Hurwitz–Radon function defined as \rho(n)=2^b+8c for nonnegative integers a, b, c such that n=(2a+1)2^{b+4c} and 0<= b < 4. If m<=\rho(n), then the set of m x n x (m-1)n tensors has two typical ranks (m-1)n, (m-1)n+1. In this paper, we show that the converse is also true: if m>\rho(n), then the set of m x n x (m-1)n tensors has only one typical rank (m-1)n..
9. Toshio Sumi, Centralizers of gap groups, Fundamenta Mathematicae, fm226-2-1, 226, 101-121, 2014.06, A finite group G is called a gap group if there exists an RG-module which has no large isotropy groups except at zero and satisfies the gap condition. The gap condition facilitates the process of equivariant surgery. Many groups are gap groups and also many groups are not. In this paper, we clarify the relation between a gap group and the structures of its centralizers. We show that a nonsolvable group which has a normal, odd prime power index proper subgroup is a gap group..
10. 角 俊雄, Smith sets of non-solvable groups whose nilquotients are cyclic groups of order 1,2, or 3, RIMS Kokyuroku Bessatsu, B39, 149-165, 2013.06, Let $G$ be a finite group.
Two real $G$-modules $U$ and $V$ are called Smith equivalent
if there exists a smooth action of $G$
on a sphere with two fixed points at which tangential representations are isomorphic to $U$ and $V$ respectively. The Smith set of $G$ is the subset of the real representation ring of $G$ consisting differences of Smith equivalent $G$-modules. We discuss when the Smith set of an Oliver group becomes an abelian group and give several examples of non-solvable groups of which the Smith sets are groups.
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11. Krzysztof Pawalowski, Toshio Sumi, The Laitinen Conjecture for finite non-solvable groups, http://dx.doi.org/10.1017/S0013091512000223, 56, 1, 303-336, 2013.02, For any finite group G, we impose an algebraic condition, the G^{nil}-coset condition, and prove that any finite Oliver group G satisfying the G^{nil}-coset condition has a smooth action on some sphere with isolated fixed points at which the tangent G-modules are not isomorphic to each other. Moreover, we prove that, for any finite non-solvable group G not isomorphic to Aut(A_{6}) or PΣL(2, 27), the G\sup{nil}-coset condition holds if and only if r_{G} ≥ 2, where r_{G} is the number of real conjugacy classes of elements of G not of prime power order. As a conclusion, the Laitinen Conjecture holds for any finite non-solvable group not isomorphic to Aut(A_{6})..
12. Toshio Sumi, Mitsuhiro Miyazaki, Toshio Sakata, Typical ranks for m x n x (m-1)n tensors with m<=n, Linear Algebra and its Applications, 10.1016/j.laa.2011.08.009, 438, 2, 953-958, 2013.01, In various application fields, tensor type data are used recently and
then a typical rank is important. There may be more than one typical
ranks over the real number field. It is well known that the set of
2 × n × n tensors has two typical ranks n, n + 1 for n>=2, that the
set of 3 × 4 × 8 tensors has two typical ranks 8, 9, and that the set
of 4×4×12 tensors has two typical ranks 12, 13. In this paper, we
show that the set of m×n×(m−1)n tensors with m<=n has two
typical ranks (m − 1)n, (m − 1)n + 1 if m<=ρ(n), where ρ is the
Hurwitz–Radon function..
13. Toshio Sumi, The gap hypothesis for finite groups which have an abelian quotient group not of order a power of 2, Journal of the Mathematical Society of Japan, 10.2969/jmsj/06410091, 64, 1, 91-106, 2012.01.
14. Toshio Sumi and Toshio Sakata, Connectivity for 3x3xK contingency tables, Journal of Algebraic Statistics, 2, 1, 54-74, 2011.08.
15. Toshio Sumi and Toshio Sakata, 2-neighborhood theorem for 3x3x3 contingency tables, Journal of the Indian Society for Probability and Statistics, 12, 66-84, 2010.12.
16. Toshio Sumi and Toshio Sakata, The Set of 3x4x4 Contingency Tables has 3-Neighborhood Property, Proceedings of COMPSTAT'2010, Electronic Supplementary Material (e-book)
19th International Conference on Computational Statistics, Paris France, August 22-27, 2010
, 1629-1636, 2010.09.
17. Toshio Sumi, Mitsuhiro Miyazaki, and Toshio Sakata, About the maximal rank of 3-tensors over the real and the complex number field, Ann. Inst. Stat. Math., 10.1007/s10463-010-0294-5, 62, 807-822, 2010.09.
18. Toshio Sumi, Mitsuhiro Miyazaki, and Toshio Sakata, Rank of 3-tensors with 2 slices and Kronecker canonical forms, Linear Algebra and its Applications, vol. 431, 1858-1868, 2009.10.
19. Krzysztof Pawalowski and Toshio Sumi, The Laitinen Conjecture for finite solvable Oliver groups, Proceedings of American Mathematical Society, Proceedings of the American Mathematical Society 137 (6), 2147-2156, 2009, 2009.06.
主要総説, 論評, 解説, 書評, 報告書等
1. Toshio Sumi, Alternating groups and Borsuk-Ulam groups, RIMS講究録 2135, 2019.11.
2. 角 俊雄, Finite groups with Smith equivalent, nonisomorphic representations, 変換群論シンポジューム2006報告集, 2006.11.
主要学会発表等
1. Toshio Sumi, Construction of gap modules, The 41st Symposium on Transformation Groups, 2014.11.
2. Toshio Sumi, Note on tangential representations on a sphere, Joint Meeting of the German Mathematical Society and the Polish Mathematical Society, 2014.09, Our target is Smith sets for Oliver groups. A solvable Oliver group possessing non-trivial Smith set is not determined, but we know completely for non-solvable groups. In this talk, we give many non-solvable groups of which Smith set are additive groups.
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3. 角 俊雄, The Smith equivalence problem and Smith sets of Oliver groups, 日本数学会秋季総合分科会, 2012.09.
4. Toshio Sumi, The Smith equivalence problems for finite Oliver groups, Geometry of manifolds and group actions, 2012.09, Let G be a finite group. A real G-module V is a finite dimensional real vector space with a linear G-action. Two real G-modules U and V are called Smith equivalent if there exists a smooth G-action on a homotopy sphere with exactly two fixed points, at which the tangential G-modules are isomorphic to U and V, respectively. The Smith equivalence problem is stated as follows.
Is it true that two Smith equivalent G-modules are isomorphic? In this talk, I would like to introduce a history of this problem and recent results..
5. 角 俊雄, Nonsolvable groups of which the Smith sets are groups, 変換群論シンポジウム, 2011.11.
6. 角 俊雄、坂田 年男、宮崎 充弘, Existence and construction of absolutely nonsingular tensors, 第28回代数的組合せ論シンポジウム, 2011.06.
作品・ソフトウェア・データベース等
1. 角 俊雄, KNOT, 2000.02
児玉氏が Linux 用に開発した、結び目・絡み目の不変量を計算するプログラムを、Windows, Mac 上に 2000年に移植した。2012年には、メンテナンスとして、OSのバージョンアップやCPU の64bit化に対応した。
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学会活動
所属学会名
日本数学会
学会大会・会議・シンポジウム等における役割
2019.08.08~2019.08.08, トポロジーシンポジウム, 座長.
2019.05.29~2019.05.29, RIMS共同研究(公開型)「変換群論とその応用」, 座長(Chairmanship).
2018.12.09~2018.12.09, Workshop on Geometric Discrete Mathematics II, 世話人.
2017.05.23~2017.05.23, RIMS共同研究(公開型)「変換群を核とする代数的位相幾何学」, 座長(Chairmanship).
2013.05.28~2013.05.28, RIMS研究集会「変換群のトポロジーとその周辺」, 座長(Chairmanship).
2013.09.18~2013.09.21, 日本数学会, 司会(Moderator).
2012.05.28~2012.06.01, 変換群の幾何の展開, 司会(Moderator).
2011.11.18~2011.11.20, 変換群論シンポジューム, 座長(Chairmanship).
2010.11.23~2010.11.25, 変換群論シンポジューム, 座長(Chairmanship).
2009.12.10~2009.12.12, 変換群論シンポジューム, 座長(Chairmanship).
2008.11.11~2008.11.13, 変換群論シンポジューム, 座長(Chairmanship).
2006.05~2006.05, 変換群論の手法, 司会(Moderator).
2013.03.12~2013.03.13, シンポジューム Structures and Symmetries on Manifolds, 世話人.
2012.05.28~2012.06.01, RIMS研究集会「変換群の幾何の展開」, 世話人、座長.
2010.11.23~2010.11.25, 変換群論シンポジューム, 世話人、座長.
2009.12.10~2009.12.12, 変換群論シンポジューム, 世話人、座長.
学術論文等の審査
年度 外国語雑誌査読論文数 日本語雑誌査読論文数 国際会議録査読論文数 国内会議録査読論文数 合計
2019年度
2018年度
2016年度      
2015年度      
2014年度      
2013年度      
2012年度      
2011年度
2008年度      
2007年度
その他の研究活動
海外渡航状況, 海外での教育研究歴
Adam Mickiewicz University, Poland, 2014.09~2014.09.
Collegium Polonicum of the Adam Mickiewicz University, Poland, 2013.09~2013.09.
Gdansk University of Technology, Adam Mickiewicz University, Poland, Poland, 2012.09~2012.09.
University of Milano-Bicocca, Italy, 2010.09~2010.09.
Conservatoire National des Arts et des Métiers, France, 2010.08~2010.08.
Andhra University, India, 2009.12~2010.01.
Comenius University, SlovakRepublic, 2009.09~2009.09.
Universidade do Porto, Portugal, 2008.08~2008.09.
the Congress Center of Holiday inn Hotel, ブルノ工科大学, CzechRepublic, 2008.06~2008.07.
Queen Mary, Mile End Campus, UnitedKingdom, 2007.09~2007.09.
Warszawa University, Poland, 2007.07~2007.08.
Press Center, Seoul, Korea, 2007.06~2007.06.
Malaga University, Spain, 2006.09~2006.09.
Jagiellonian University, Congress Centre, Poland, 2005.06~2005.07.
Jagiellonian University, Adam Mickiewicz University, Poland, Poland, 2004.06~2004.06.
Helsinki University, Adam Mickiewicz University, Finland, Poland, 2003.08~2003.08.
研究資金
科学研究費補助金の採択状況(文部科学省、日本学術振興会)
2016年度~2018年度, 基盤研究(C), 代表, 多重線形写像の実射影空間への像とテンソル階数への応用.
2012年度~2015年度, 基盤研究(C), 代表, 多様体上の有限群作用の軟性について.
2002年度~2004年度, 基盤研究(C), 代表, 有限群の表現と不動点集合を実現する有限群作用に関する研究.
2005年度~2007年度, 基盤研究(C), 代表, 多様体における有限群作用の固定点上の接空間となる表現に関する研究.

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