MATHEMATICAL ENGINEERING TECHNICAL REPORTS Arrangements Stable Under the Coxeter Groups

Total Page:16

File Type:pdf, Size:1020Kb

MATHEMATICAL ENGINEERING TECHNICAL REPORTS Arrangements Stable Under the Coxeter Groups MATHEMATICAL ENGINEERING TECHNICAL REPORTS Arrangements Stable under the Coxeter Groups Hidehiko KAMIYA, Akimichi TAKEMURA and Hiroaki TERAO METR 2011{10 March 2011 DEPARTMENT OF MATHEMATICAL INFORMATICS GRADUATE SCHOOL OF INFORMATION SCIENCE AND TECHNOLOGY THE UNIVERSITY OF TOKYO BUNKYO-KU, TOKYO 113-8656, JAPAN WWW page: http://www.keisu.t.u-tokyo.ac.jp/research/techrep/index.html The METR technical reports are published as a means to ensure timely dissemination of scholarly and technical work on a non-commercial basis. Copyright and all rights therein are maintained by the authors or by other copyright holders, notwithstanding that they have offered their works here electronically. It is understood that all persons copying this information will adhere to the terms and constraints invoked by each author's copyright. These works may not be reposted without the explicit permission of the copyright holder. Arrangements stable under the Coxeter groups Hidehiko Kamiya ∗ Faculty of Economics, Okayama University, Okayama, 700-8530, Japan Akimichi Takemura y Graduate School of Information Science and Technology, University of Tokyo, Tokyo, 113-0033, Japan Hiroaki Terao z Department of Mathematics, Hokkaido University, Sapporo, 060-0810, Japan March 2011 Abstract Let B be a real hyperplane arrangement which is stable under the action of a Coxeter group W . Then W acts naturally on the set of chambers of B. We assume that B is disjoint from the Coxeter arrangement A = A(W ) of W . In this paper, we show that the W -orbits of the set of chambers of B are in one-to- one correspondence with the chambers of C = A[B which are contained in an arbitrarily fixed chamber of A. From this fact, we find that the number of W -orbits of the set of chambers of B is given by the number of chambers of C divided by the order of W . We will also study the set of chambers of C which are contained in a chamber b of B. We prove that the cardinality of this set is equal to the order of the isotropy subgroup Wb of b. We illustrate these results with some examples, and solve an open problem in Kamiya, Takemura and Terao [Ranking patterns of unfolding models of codimension one, Adv. in Appl. Math. (2010)] by using our results. Keywords: all-subset arrangement, braid arrangement, characteristic polynomial, Cox- eter arrangement, Coxeter group, finite-field method, mid-hyperplane arrangement, sym- metric group. MSC2010: 20F55, 32S22, 52C35. 1 Introduction Let B be a real hyperplane arrangement which is stable under the action of a Coxeter group W . Then W acts naturally on the set Ch(B) of chambers of B. We want to find the number of W -orbits of Ch(B). A particular case of this problem was considered in ∗This work was partially supported by JSPS KAKENHI (22540134). yThis research was supported by JST CREST. zThis work was partially supported by JSPS KAKENHI (21340001). 1 the authors' previous paper (Kamiya, Takemura and Terao [9]) and the present paper is motivated by an open problem left in Section 6 of [9]. By the general results of the present paper, we give the affirmative answer to the open problem in Theorem 3.1. Suppose throughout that B\A = ;, where A = A(W ) is the Coxeter arrangement of W . In this paper, we will show that the orbit space of Ch(B) is in one-to-one correspondence with the set of chambers c of C = A[B which are contained in a, fc 2 Ch(C) j c ⊆ ag, where a 2 Ch(A) is an arbitrary chamber of A. From this fact, we find that the number of W -orbits of Ch(B) is given by jCh(C)j=jW j. On the other hand, we will also study the set of chambers c 2 Ch(C) which are contained in a chamber b 2 Ch(B) of B, fc 2 Ch(C) j c ⊆ bg. We will prove that the cardinality of this set is equal to the order of the isotropy subgroup Wb of b. Moreover, we will investigate the structure of Wb. Kamiya, Takemura and Terao [9] tried to find the number of \inequivalent ranking patterns generated by unfolding models of codimension one" in psychometrics, and ob- tained an upper bound for this number. It was left open to determine whether this upper bound is actually the exact number. The problem boils down to proving (or disprov- ing) that the orbit space of the chambers of the restricted all-subset arrangement ([9]) B under the action of the symmetric group Sm is in one-to-one correspondence with fc 2 Ch(A(Sm) [B) j c ⊆ ag for a chamber a 2 Ch(A(Sm)) of the braid arrangement A(Sm). The results of the present paper establish the one-to-one correspondence. The paper is organized as follows. In Section 2, we verify our main results. Next, in Section 3, we illustrate our general results with four examples. Those examples are mainly taken from the authors' previous studies of unfolding models in psychometrics ([5], [9]). In Section 3, we also solve the open problem of [9] (Theorem 3.1) using our general results in Section 2 applied to one of our examples. 2 Main results In this section, we state and prove our main results. Let V be a Euclidean space. Consider a Coxeter group W acting on V . Then the Coxeter arrangement A = A(W ) is the set of all reflecting hyperplanes of W . Suppose that B is a hyperplane arrangement which is stable under the natural action of W . We assume A\B = ; and define C := A[B: Let Ch(A), Ch(B) and Ch(C) denote the set of chambers of A, B and C, respectively. Define 'A : Ch(C) ! Ch(A);'B : Ch(C) ! Ch(B) by 'A(c) := the chamber of A containing c; 'B(c) := the chamber of B containing c for c 2 Ch(C). Note that the Coxeter group W naturally acts on Ch(A), Ch(B) and Ch(C). 2 Lemma 2.1. 'A and 'B are both W -equivariant, i.e., 'A(wc) = w('A(c));'B(wc) = w('B(c)) for any w 2 W and c 2 Ch(C). The proof is easy and omitted. The following result is classical (see, e.g., [3, Ch. V, x3. 2. Theorem 1 (iii) ]): Theorem 2.2. The group W acts on Ch(A) effectively and transitively. In particular, jW j = jCh(A)j. By Theorem 2.2, we can prove the following lemma. Lemma 2.3. The group W acts on Ch(C) effectively. In particular, each W -orbit of Ch(C) is of size jW j. Proof. If wc = c for w 2 W and c 2 Ch(C), then we have 'A(c) = w'A(c); which implies w = 1 by Theorem 2.2. For b 2 Ch(B), define the isotropy subgroup Wb := fw 2 W j wb = bg. Then we have −1 Lemma 2.4. For b 2 Ch(B), the group Wb acts on 'B (b) effectively and transitively. Proof. The effective part follows from Lemma 2.3, so let us prove the transitivity. −1 Let c1; c2 2 'B (b). Define A(c1; c2) := fH 2 A j c1 and c2 are on different sides of Hg: Let us prove that there exists w 2 W such that wc1 = c2 by an induction on jA(c1; c2)j. When jA(c1; c2)j = 0, we have A(c1; c2) = ; and c1 = c2. Thus we may choose w = 1. If A(c1; c2) is non-empty, then there exists H1 2 A(c1; c2) such that H1 contains a wall of c1. Let s1 denote the reflection with respect to H1. Then A(s1c1; c2) = A(c1; c2) n fH1g: By the induction assumption, there exists w1 2 W with w1s1c1 = c2. Set w := w1s1. Then wc1 = c2 and c2 = (wc1) \ c2 ⊆ (wb) \ b, which implies that (wb) \ b is not empty. Thus wb = b and w 2 Wb. The following lemma states that the W -orbits of Ch(C) and those of Ch(B) are in one-to-one correspondence. Lemma 2.5. The map 'B : Ch(C) ! Ch(B) induces a bijection from the set of W -orbits of Ch(C) to the set of W -orbits of Ch(B). Proof. For b 2 Ch(B) and c 2 Ch(C), we denote the W -orbit of b and the W -orbit of c by O(b) and by O(c), respectively. It is easy to see that 'B(O(c)) = O('B(c)); c 2 Ch(C); 3 by Lemma 2.1. Thus 'B induces a map from the set of W -orbits of Ch(C) to the set of W -orbits of Ch(B). We will show the map is bijective. Surjectivity: Let O(b) be an arbitrary orbit of Ch(B) with a representative point −1 b 2 Ch(B). Take an arbitrary c 2 'B (b). Then 'B(O(c)) = O('B(c)) = O(b); which shows the surjectivity. Injectivity: Suppose 'B(O(c1)) = 'B(O(c2)) (c1; c2 2 Ch(C)). Set bi := 'B(ci) for i = 1; 2. We have O(b1) = O('B(c1)) = 'B(O(c1)) = 'B(O(c2)) = O('B(c2)) = O(b2); so we can pick w 2 W such that wb2 = b1. Then 'B(wc2) = w('B(c2)) = wb2 = b1: −1 Therefore, both c1 and wc2 lie in 'B (b1). By Lemma 2.4, we have O(c1) = O(wc2) = O(c2): We are now in a position to state the main results of this paper.
Recommended publications
  • Report for the Academic Year 1995
    Institute /or ADVANCED STUDY REPORT FOR THE ACADEMIC YEAR 1994 - 95 PRINCETON NEW JERSEY Institute /or ADVANCED STUDY REPORT FOR THE ACADEMIC YEAR 1 994 - 95 OLDEN LANE PRINCETON • NEW JERSEY 08540-0631 609-734-8000 609-924-8399 (Fax) Extract from the letter addressed by the Founders to the Institute's Trustees, dated June 6, 1930. Newark, New jersey. It is fundamental in our purpose, and our express desire, that in the appointments to the staff and faculty, as well as in the admission of workers and students, no account shall be taken, directly or indirectly, of race, religion, or sex. We feel strongly that the spirit characteristic of America at its noblest, above all the pursuit of higher learning, cannot admit of any conditions as to personnel other than those designed to promote the objects for which this institution is established, and particularly with no regard whatever to accidents of race, creed, or sex. TABLE OF CONTENTS 4 BACKGROUND AND PURPOSE 5 • FOUNDERS, TRUSTEES AND OFFICERS OF THE BOARD AND OF THE CORPORATION 8 • ADMINISTRATION 11 REPORT OF THE CHAIRMAN 15 REPORT OF THE DIRECTOR 23 • ACKNOWLEDGMENTS 27 • REPORT OF THE SCHOOL OF HISTORICAL STUDIES ACADEMIC ACTIVITIES MEMBERS, VISITORS AND RESEARCH STAFF 36 • REPORT OF THE SCHOOL OF MATHEMATICS ACADEMIC ACTIVITIES MEMBERS AND VISITORS 42 • REPORT OF THE SCHOOL OF NATURAL SCIENCES ACADEMIC ACTIVITIES MEMBERS AND VISITORS 50 • REPORT OF THE SCHOOL OF SOCIAL SCIENCE ACADEMIC ACTIVITIES MEMBERS, VISITORS AND RESEARCH STAFF 55 • REPORT OF THE INSTITUTE LIBRARIES 57 • RECORD OF INSTITUTE EVENTS IN THE ACADEMIC YEAR 1994-95 85 • INDEPENDENT AUDITORS' REPORT INSTITUTE FOR ADVANCED STUDY: BACKGROUND AND PURPOSE The Institute for Advanced Study is an independent, nonprofit institution devoted to the encouragement of learning and scholarship.
    [Show full text]
  • Mathematical Society
    Notices of the American Mathematical Society November 1983, Issue 229 Volume 30, Number 7, Pages 713-840 Providence, Rhode Island USA ISSN 0002-9920 Calendar of AMS Meetings THIS CALENDAR lists all meetings which have been approved by the Council prior to the date this issue of the Notices was sent to press. The summer and annual meetings are joint meetings of the Mathematical Association of America and the Ameri· can Mathematical Society. The meeting dates which fall rather far in the future are subject to change; this is particularly true of meetings to which no numbers have yet been assigned. Programs of the meetings will appear in the issues indicated below. First and second announcements of the meetings will have appeared in earlier issues. ABSTRACTS OF PAPERS presented at a meeting of the Society are published in the journal Abstracts of papers presented to the American Mathematical Society in the issue corresponding to that of the Notices which contains the program of the meet­ ing. Abstracts should be submitted on special forms which are available in many departments of mathematics and from the office of the Society in Providence. Abstracts of papers to be presented at the meeting must be received at the headquarters of the Society in Providence, Rhode Island, on or before the deadline given below for the meeting. Note that the deadline for ab­ stracts submitted for consideration for presentation at special sessions is usually three weeks earlier than that specified below. For additional information consult the meeting announcement and the list of organizers of special sessions.
    [Show full text]
  • Characteristic Polynomial of Arrangements and Multiarrangements
    Western University Scholarship@Western Electronic Thesis and Dissertation Repository 4-21-2011 12:00 AM Characteristic Polynomial of Arrangements and Multiarrangements Mehdi Garrousian The University of Western Ontario Supervisor Dr. Graham Denham The University of Western Ontario Graduate Program in Mathematics A thesis submitted in partial fulfillment of the equirr ements for the degree in Doctor of Philosophy © Mehdi Garrousian 2011 Follow this and additional works at: https://ir.lib.uwo.ca/etd Part of the Algebra Commons, Algebraic Geometry Commons, and the Discrete Mathematics and Combinatorics Commons Recommended Citation Garrousian, Mehdi, "Characteristic Polynomial of Arrangements and Multiarrangements" (2011). Electronic Thesis and Dissertation Repository. 142. https://ir.lib.uwo.ca/etd/142 This Dissertation/Thesis is brought to you for free and open access by Scholarship@Western. It has been accepted for inclusion in Electronic Thesis and Dissertation Repository by an authorized administrator of Scholarship@Western. For more information, please contact [email protected]. Characteristic Polynomial of Arrangements and Multiarrangements (Spine title: Characteristic Polynomial of Arrangements) (Thesis format: Monograph) by Mehdi Garrousian Graduate Program in Mathematics A thesis submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy School of Graduate and Postdoctoral Studies The University of Western Ontario London, Ontario, Canada c Mehdi Garrousian 2011 Certificate of Examination THE UNIVERSITY
    [Show full text]
  • Notices of the American Mathematical Society
    Notices of the American Mathematical Society November 1985, Issue 244 Volume 32, Number 6, Pages 737- 872 Providence, Rhode Island USA ISSN 0002-9920 Calendar of AMS Meetings THIS CALENDAR lists all meetings which have been approved by the Council prior to the date this issue of the Notices was sent to the press. The summer and annual meetings are joint meetings of the Mathematical Association of America and the American Mathematical Society. The meeting dates which fall rather far in the future are subject to change: this is particularly true of meetings to which no numbers have yet been assigned. Programs of the meetings will appear in the issues indicated below. First and supplementary announcements of the meetings will have appeared in earlier issues. ABSTRACTS OF PAPERS presented at a meeting of the Society are published in the journal Abstracts of papers presented to the American Mathematical Society in the issue corresponding to that of the Notices which contains the program of the meeting. Abstracts should be submitted on special forms which are available in many departments of mathematics and from the headquarters office of the Society. Abstracts of papers to be presented at the meeting must be received at the headquarters of the Society in Providence. Rhode Island, on or before the deadline given below for the meeting. Note that the deadline for abstracts for consideration for presentation at special sessions is usually three weeks earlier than that specified below. For additional information consult the meeting announcements and the list of organizers of special sessions. ABSTRACT MEETING# DATE PLACE DEADLINE ISSUE 825 January 7-11.
    [Show full text]
  • Arxiv:1806.05410V1 [Math.AG] 14 Jun 2018 the Differential Operator of Order Zero Given by Multiplication by F
    THE ALGEBRA OF DIFFERENTIAL OPERATORS TANGENT TO A HYPERPLANE ARRANGEMENT MARIANO SUAREZ-´ ALVAREZ´ Let us fix a ground field |, once and for all, and a vector space V of positive dimension `, and let S be the graded algebra of polynomial functions on V . Let A be a central hyperplane arrangement in V , that is, a set of subspaces H1,..., Hr ∗ of V of codimension 1, and for each i 2 f1; : : : ; `g let αi 2 V be a linear form on V such that Hi = ker αi. The product Q = α1 ··· αr 2 S, which we call a defining Sr polynomial of the arrangement, has zero locus equal to the union N(A) = i=1 Hi of the hyperplanes of A and depends, up to a non-zero scalar, only on the arrangement. We write Der(S) the Lie algebra of all derivations of S endowed with its usual structure of a graded left S-module and for each ideal I ⊆ S we consider the set Der(I) = fδ 2 Der(S): δ(I) ⊆ Ig, which is both a Lie subalgebra and a graded S-submodule of Der(S). The Lie algebra Der(A) of derivations tangent to A is Der(QS) and the arrangement is free if Der(A) is a free graded S-module. This notion was introduced in the context of the study of logarithmic vector fields related to a hypersurface of a smooth complex analytic manifold by Kyoji Saito in [6]. We do not know what exactly makes an arrangement free and it is not a generic property, but we have plenty of evidence that freeness is both important and useful, and it shows up in many contexts.
    [Show full text]
  • CURRICULUM VITA July 26, 2021 Name: TERAO, Hiroaki (Mr.)
    CURRICULUM VITA July 26, 2021 Name: TERAO, Hiroaki (Mr.) Sex: Male Present Address: Hiroaki Terao 1-19-8 Minamisenzoku Ota-ku, Tokyo 145-0063 JAPAN Tel. 090-8518-7831 e-mail: [email protected] Date of birth: August 13, 1951 Birth Place: Tokyo, Japan Education: 1. University of Tokyo, B. Sc., March 1974 2. University of Tokyo, M. Sc., March 1976 3. Kyoto University, D. Sc.(論文博士), Mar. 1981 Current Positions: 1. Hokkaido University, Professor Emeritus (名誉教授), April 1, 2015 - 2. Tokyo Metropolitan University (東京都立大学), Guest Professor (客員教 授), June 1, 2017 - 3. Tokyo Institute of Technology, Faculty of Sciences, Research Fellow (特 別研究員), Apr. 1, 2017- 4. Science Council of Japan (日本学術会議), Member (連携会員), Oct. 1, 2014 - Full-Time University Positions: 1. International Christian University, Assistant, Apr. 1977-Mar. 1979 2. International Christian University, Instructor, Apr. 1979-Mar. 1981 3. International Christian University, Assistant Professor, Apr. 1981-Mar. 1985 4. University of Wisconsin (Madison), Visiting Assistant Professor, Sep. 1982-Jun. 1983 1 5. International Christian University, Associate Professor, Apr. 1985- Sep. 1991 6. Ohio State University, Visiting Associate Professor, Sep. 1987-June 1988 7. University of Wisconsin (Madison), Visiting Associate Professor, Sep. 1988-Aug. 1990 8. University of Wisconsin (Madison), Associate Professor, Aug. 1990- May 1993 9. University of Wisconsin (Madison), Professor, Aug. 1993-May 1999 10. Hokkaido University, Professor, July 1, 1996 - March 31, 1998 11. Tokyo Metropolitan University, Professor, April 1, 1998 - March 31, 2006 12. Hokkaido University, Professor, Faculty of Science, April 1, 2006 - March 31, 2015 13. Hokkaido University, Dean, Graduate School of Science (理学院長), April 1, 2011 - March 31, 2015 14.
    [Show full text]
  • Max Douglas Wakefield
    Max Douglas Wakefield Curriculum Vita Department of Mathematics Phone:410-293-6783 United States Naval Academy wakefi[email protected] 572C Holloway Rd http://www.usna.edu/Users/math/wakefiel/ Annapolis, MD 21402 Citizenship: USA USA Born: 7-15-1977, Kodiak, Alaska. Education Ph.D. in Mathematics,UNIVERSITY OF OREGON, June 2006. Dissertation: On the derivation module and apolar algebra of an arrangement of hyperplanes. Advisor: Sergey Yuzvinsky. M.S. in Mathematics,UNIVERSITY OF OREGON, June 2003. B.S. in Mathematics,SEATTLE UNIVERSITY, June 2001. Academic Visiting Associate Professor, University of Oregon, Fall 2014. Positions Associate Professor, United States Naval Academy, August 2013- Present. Assistant Professor, United States Naval Academy, August 2008- July 2013. NSF International Research Fellow, Hokkaido University, September 2006 - July 2008. Research Associate, Mathematical Sciences Research Institute, August 2004 - December 2004. Graduate Teaching Fellow, University of Oregon, September 2001 - June 2006. Research Commutative algebra, combinatorics, algebraic geometry, algebraic topology, arrange- Interests ments of hyperplanes, cryptography, and error-correcting codes. Publications [1] Derivations of an effective divisor on the complex projective line, Trans. Amer. Math. Soc. 359 (2007), 4389-4403. (with S. Yuzvinsky) [2] The characteristic polynomial of a multiarrangement, Adv. Math. 215 (2007), 825-838. (with T. Abe and H. Terao) [3] The Euler multiplicity and addition-deletion theorems for multiarrangements, J. London Math. Soc.(2) 77 (2008), no. 2, 335{348. (with T. Abe and H. Terao) [4] The Jacobian ideal of a hyperplane arrangement, Math. Res. Let. 15 (2008), no. 4,795-799. (with M. Yoshinaga) [5] Pascal arrangements, Proc. Amer. Math. Soc. 139 (2011), no.
    [Show full text]
  • ARRANGEMENTS of HYPERPLANES Algebra, Combinatorics, Geometry and Topology
    ARRANGEMENTS OF HYPERPLANES Algebra, Combinatorics, Geometry and Topology Centro Stefano Franscini, Ascona, Switzerland May 16 { May 20, 2005 List of Participants Takuro Abe (Kyoto University, Japan) [email protected] Eric Babson (University of Washington, USA) [email protected] Silvano Baggio (Universit´a di Bologna, Italy) [email protected] Filippo Callegaro (Scuola Normale Superiore Pisa, Italy) [email protected] Daniel Cohen (Louisiana State University, USA) [email protected] Peter Csorba (ETH Zurich, Switzerland) [email protected] Sonja Cukic (KTH Stockholm, Sweden) [email protected] Ehud de Shalit (Hebrew University, Israel) [email protected] Emanuele Delucchi (ETH Zurich, Switzerland) [email protected] Graham Denham (University of Western Ontario, Canada) [email protected] Alexandru Dimca (Universit´e de Nice, France) [email protected] Igor Dolgachev (University of Michigan, USA) [email protected] Alexander Engstr¨om (ETH Zurich, Switzerland) [email protected] Michael Falk (Northern Arizona University, USA) [email protected] Kwai-Man Fan (National Chung Cheng University, Taiwan) [email protected] Eva Maria Feichtner (ETZ Zurich, Switzerland) [email protected] Giovanni Gaiffi (Scuola Normale Superiore Pisa, Italy) [email protected] Yukihito Kawahara (Tokyo Metropolitan University, Japan) [email protected] Toshitake Kohno (University of Tokyo, Japan) [email protected] Dmitry Kozlov (ETH Zurich, Switzerland) [email protected] Paulo Lima-Filho (Texas A&M University, USA) [email protected]
    [Show full text]
  • Singularities Proceedings of the IMA Participating Institutions Conference Held July 28-August 1, 1986
    Singularities Proceedings of the IMA Participating Institutions Conference held July 28-August 1, 1986 AMERICAn MATHEMATICAL SOCIETY UOLUME BO http://dx.doi.org/10.1090/conm/090 Titles in This Series Volume 1 Markov random fields and their 19 Proceedings of th~ Northwestern applications, Ross Kindermann and homotopy theory conference, Haynes J. Laurie Snell R. Miller and Stewart B. Priddy, Editors 2 Proceedings of the conference on 20 Low dimensional topology, Samuel J. integration, topology, and geometry in Lomonaco, Jr., Editor linear spaces, William H. Graves, Editor 21 Topological methods in nonlinear 3 The closed graph and P-closed functional analysis, S. P. Singh, graph properties in general topology, S. Thomaier, and B. Watson, Editors T. R. Hamlett and L. L. Herrington 22 Factorizations of b" ± 1, b = 4 Problems of elastic stability and 2, 3, 5, 6, 7, 10, vibrations, Vadim Komkov, Editor 11, 12 up to high powers, John Brillhart, 5 Rational constructions of modules D. H. Lehmer, J. L. Selfridge, Bryant for simple Lie algebras, George B. Tuckerman, and S. S. Wagstaff, Jr. Seligman 23 Chapter 9 of Ramanujan's second 6 Umbral calculus and Hopf algebras, notebook-Infinite series identities, Robert Morris, Editor transformations, and evaluations, Bruce C. Berndt and Padmini T. Joshi 7 Complex contour integral representation of cardinal spline 24 Central extensions, Galois groups, and functions, Walter Schempp ideal class groups of number fields, A. Frohlich 8 Ordered fields and real algebraic geometry, D. W. Dubois and T. Recio, 25 Value distribution theory and its Editors applications, Chung-Chun Yang, Editor 9 Papers in algebra, analysis and 26 Conference in modern analysis statistics, R.
    [Show full text]