九州大学 組合せ数学セミナー
～ Combinatorics Seminar in Kyushu University ～
20130126
をテンプレートにして作成
開始行:
* Hakata Workshop 2013 [#z008da3b]
''～ Combinatrics and its Applications～''
#br
This is a satellite seminar of [[the 11th Japan-Korea Wor...
Our purpose of this meeting is giving an opportunity to m...
to commuticate with reserchers who study verious fields n...
Further information is available from the organizers below.
**Organizers [#xb11a6e1]
-[[Yoshihiro Mizoguchi:http://imi.kyushu-u.ac.jp/~ym/]] (...
-Hayato Waki (Kyushu University),~
-Mitsugu Hirasaka (Pusan National University),~
-[[Tetsuji Taniguchi:http://researchmap.jp/tetsuzit-14/]]...
-Osamu Shimabukuro (Sojo University)
-[[Laboratory of Advanced Software in Mathematics, Instit...
**Supported by [#l7bc435b]
-[[Global COE Program "Education and Research Hub for Mat...
**Date [#i35500dd]
-January 26, 2013. 9:30-18:00
**Location [#vcadf025]
-Seminar Room I (2F) in Reference Eki Higashi Building.
1-16-14 Hakata-Eki-Higashi, Hakata-Ku, Fukuoka City, 812-...
(see http://www.re-rental.com/ , [[Google maps:http://map...
**Program [#h6d29d6d]
***January 26 (Saturday) at Room I in Reference Eki Higas...
-9:25--9:30 Opening (Tetsuji Taniguchi)
-9:30--10:05 [[Akihiro Munemasa (Tohoku University)>#pa19...
--Complex Hadamard matrices contained in a Bose-Mesner al...
-10:20--10:55 [[Michael Dobbins (GAIA, Postech)>#ze9edc62]]
--Reducing combinatorial to projective equivalence in rea...
-11:10--11:45 [[Aleksandar Jurišić (University of Ljublja...
--TOWER GRAPHS AND EXTENDED GENERALIZED QUADRANGLES
-12:00--13:00 break
-13:00--15:00 Poster Session
--[[List of Speakers>#cfb76d77]]
-15:15--16:15 [[Xiao-Dong Zhang (Shanghai Jiao Tong Unive...
--The algebraic connectivity of graphs
-16:30--17:05 [[Katsuhiro Ota (Keio University)>#mb37f86c]]
--Clique minors, chromatic numbers for degree sequences
-17:10--17:45 [[Yota Otachi (JAIST)>#h17d65f1]]
--The path-distance-width of hypercubes
-17:45--18:00 Closing (Yoshihiro Mizoguchi)
-18:00-- Post-meeting party
**List of Poster session speakers [#cfb76d77]
*** 「[[数学ソフトウェア紹介:http://imi.kyushu-u.ac.jp/~w...
+岩淵 勇樹 (面白法人カヤック), プログラム名: GraphiC...
+久保 浩平(九州大学理学部物理学科), プログラム名: 正規圧...
+島袋 修(崇城大学 工学部), プログラム名: フュージョンスキ...
+野崎 寛(愛知教育大学), プログラム名: Magmaによる極大2距...
+松下昂平(九州大学大学院数理学府), プログラム名: アフィン...
+鹿間 章宏(大阪大学大学院 情報科学研究科), プログラム名: ...
+照本 直敏(九州大学数理学府), プログラム名: Q-det
+喜友名 朝也(九州大学大学院数理学府), プログラム名: PARI/...
+谷口哲至(松江高専数理科学科), プログラム名: スターコンプ...
+ダハン グザヴィエ(ＧＣＯＥ-ＭＩ), プログラム名: MAGMAに...
+古川 貴司(九州大学大学院数理学府), プログラム名: SSD Pro...
+高妻倫太郎(立命館アジア太平洋大学), プログラム名: Truffe...
+秦攀(九州大学 マス・フォア・インダストリ研究所), プログ...
**Abstract [#sb7c7865]
***Akihiro Munemasa (Tohoku University) [#pa19cf13]
-Title:Complex Hadamard matrices contained in a Bose-Mesn...
-Abstract:
A complex Hadamard matrix &mimetex(H); is an n by n matri...
with absolute value 1, such that rows are pairwise orthog...
with respect to the hermitian inner product. Recently,
Ada Chan constructed a 15 by 15 complex Hadamard matrix u...
the adjacency matrix of the line graph of the Petersen gr...
We found another such matrix, and then generalized
it to an infinite family. In this talk, we focus on how to
set up a system of polynomial equations for solving this ...
of problem more efficiently than the naive approach. This...
achieved by determining the ideal of the 3-dimensional
algebraic variety consisting of the points of the form
&mimetex("(x+1/x,y+1/y,z+1/z,x/y+y/x,y/z+z/y,z/x+x/z)");
in the 6-dimensional space.
This is a joint work with Takuya Ikuta.
***Michael Dobbins (GAIA, Postech) [#ze9edc62]
-Title:Reducing combinatorial to projective equivalence i...
-Abstract:
Determining if there is a polytope of any combinatorial t...
satisfies some given property is made difficult by the fa...
are polytopes with realization spaces that are homotopic ...
primary semialgebraic set. I will show how, for certain p...
this can be reduced to finding such realizations among pr...
equivalence classes of polytopes, which are much nicer sp...
application of this answers a question posed by Bernt Lin...
1971, that there does exist a polytope without an antipri...
***Aleksandar Jurišić (University of Ljubljana) [#q728cf69]
-Title:TOWER GRAPHS AND EXTENDED GENERALIZED QUADRANGLES
-Abstract:
Let &mimetex(\Gamma); be a complete multipartite graph wi...
and each part of size at least &mimetex(2);. For example,...
Let now &mimetex(\Gamma); be the point graph of a general...
We study a family of graphs, denoted by &mimetex({\cal F}...
properties
(i) their &mimetex(\mu);-graphs are complete multipartite,
(ii) there exist adjacent vertices &mimetex(x);, &mimetex...
This is a generalization of the study of extended general...
in it is intimately connected with even more general stud...
strongly regular graphs.
We report on our progress of the classification of the fa...
***Xiao-Dong Zhang (Shanghai Jiao Tong University) [#wec5...
-Title:[[The algebraic connectivity of graphs:http://comb...
-Abstract:
Let &mimetex(G); be a simple graph of order &mimetex(n); ...
&mimetex( L(G)=D(G)-A(G) ); be its Laplacian matrix, wher...
The the second smallest eigenvalue of &mimetex( L(G) ); ...
In this talk, we survey some new results and progress on ...
In particular, we present some relationships between the ...
connectivity and the graph parameters, such as the cliq...
the matching number, the independence number, the isoperi...
number, etc.
***Katsuhiro Ota (Keio University) [#mb37f86c]
-Title:[[Clique minors, chromatic numbers for degree sequ...
-Abstract:
For a given graph &mimetex(G);, let &mimetex(\chi(G)); an...
the chromatic number, and the maximum size of clique mino...
respectively.
The well-known Hadwiger's conjecture (1943) states that
&mimetex(\chi(G)\le h(G)); holds for every graph &mimetex...
for the graphs with &mimetex(\chi(G)\ge 7);.
In 2005, Robertson posed the "Hadwiger's conjecture for d...
For a graphical degree sequence &mimetex(D);, let &mimete...
denote the maximum &mimetex(\chi(G)); and &mimetex(h(G));...
among the graphs &mimetex(G); having degree sequence &mim...
Robertson's conjecture states that &mimetex(\chi(D)\le h(...
sequence &mimetex(D);.
This conjecture was recently confirmed by Dvoř&aacu...
by showing strongly that &mimetex(\chi(D)\le h'(D));, where
&mimetex(h'(D)); is the maximum size of topological cliqu...
having degree sequence &mimetex(D);.
In this talk, we give an alternative and very short proof...
Robertson's conjecture.
Also, we shall discuss the values of &mimetex(\chi(D));, ...
for some &mimetex(D);.
These results are based on a joint work with Guantao Chen...
***Yota Otachi (JAIST) [#h17d65f1]
-Title: [[The path-distance-width of hypercubes:http://co...
-Abstract:
The path-distance-width of a connected graph &mimetex(G);...
integer &mimetex(w); satisfying
that there is a nonempty subset of &mimetex(S \subseteq V...
number of the vertices
with distance &mimetex(i); from &mimetex(S); is at most &...
We present a general lower bound on the path-distance-wid...
and determine the path-distance-width of hypercubes by us...
We also discuss the applicability of the lower bound to o...
終了行:
* Hakata Workshop 2013 [#z008da3b]
''～ Combinatrics and its Applications～''
#br
This is a satellite seminar of [[the 11th Japan-Korea Wor...
Our purpose of this meeting is giving an opportunity to m...
to commuticate with reserchers who study verious fields n...
Further information is available from the organizers below.
**Organizers [#xb11a6e1]
-[[Yoshihiro Mizoguchi:http://imi.kyushu-u.ac.jp/~ym/]] (...
-Hayato Waki (Kyushu University),~
-Mitsugu Hirasaka (Pusan National University),~
-[[Tetsuji Taniguchi:http://researchmap.jp/tetsuzit-14/]]...
-Osamu Shimabukuro (Sojo University)
-[[Laboratory of Advanced Software in Mathematics, Instit...
**Supported by [#l7bc435b]
-[[Global COE Program "Education and Research Hub for Mat...
**Date [#i35500dd]
-January 26, 2013. 9:30-18:00
**Location [#vcadf025]
-Seminar Room I (2F) in Reference Eki Higashi Building.
1-16-14 Hakata-Eki-Higashi, Hakata-Ku, Fukuoka City, 812-...
(see http://www.re-rental.com/ , [[Google maps:http://map...
**Program [#h6d29d6d]
***January 26 (Saturday) at Room I in Reference Eki Higas...
-9:25--9:30 Opening (Tetsuji Taniguchi)
-9:30--10:05 [[Akihiro Munemasa (Tohoku University)>#pa19...
--Complex Hadamard matrices contained in a Bose-Mesner al...
-10:20--10:55 [[Michael Dobbins (GAIA, Postech)>#ze9edc62]]
--Reducing combinatorial to projective equivalence in rea...
-11:10--11:45 [[Aleksandar Jurišić (University of Ljublja...
--TOWER GRAPHS AND EXTENDED GENERALIZED QUADRANGLES
-12:00--13:00 break
-13:00--15:00 Poster Session
--[[List of Speakers>#cfb76d77]]
-15:15--16:15 [[Xiao-Dong Zhang (Shanghai Jiao Tong Unive...
--The algebraic connectivity of graphs
-16:30--17:05 [[Katsuhiro Ota (Keio University)>#mb37f86c]]
--Clique minors, chromatic numbers for degree sequences
-17:10--17:45 [[Yota Otachi (JAIST)>#h17d65f1]]
--The path-distance-width of hypercubes
-17:45--18:00 Closing (Yoshihiro Mizoguchi)
-18:00-- Post-meeting party
**List of Poster session speakers [#cfb76d77]
*** 「[[数学ソフトウェア紹介:http://imi.kyushu-u.ac.jp/~w...
+岩淵 勇樹 (面白法人カヤック), プログラム名: GraphiC...
+久保 浩平(九州大学理学部物理学科), プログラム名: 正規圧...
+島袋 修(崇城大学 工学部), プログラム名: フュージョンスキ...
+野崎 寛(愛知教育大学), プログラム名: Magmaによる極大2距...
+松下昂平(九州大学大学院数理学府), プログラム名: アフィン...
+鹿間 章宏(大阪大学大学院 情報科学研究科), プログラム名: ...
+照本 直敏(九州大学数理学府), プログラム名: Q-det
+喜友名 朝也(九州大学大学院数理学府), プログラム名: PARI/...
+谷口哲至(松江高専数理科学科), プログラム名: スターコンプ...
+ダハン グザヴィエ(ＧＣＯＥ-ＭＩ), プログラム名: MAGMAに...
+古川 貴司(九州大学大学院数理学府), プログラム名: SSD Pro...
+高妻倫太郎(立命館アジア太平洋大学), プログラム名: Truffe...
+秦攀(九州大学 マス・フォア・インダストリ研究所), プログ...
**Abstract [#sb7c7865]
***Akihiro Munemasa (Tohoku University) [#pa19cf13]
-Title:Complex Hadamard matrices contained in a Bose-Mesn...
-Abstract:
A complex Hadamard matrix &mimetex(H); is an n by n matri...
with absolute value 1, such that rows are pairwise orthog...
with respect to the hermitian inner product. Recently,
Ada Chan constructed a 15 by 15 complex Hadamard matrix u...
the adjacency matrix of the line graph of the Petersen gr...
We found another such matrix, and then generalized
it to an infinite family. In this talk, we focus on how to
set up a system of polynomial equations for solving this ...
of problem more efficiently than the naive approach. This...
achieved by determining the ideal of the 3-dimensional
algebraic variety consisting of the points of the form
&mimetex("(x+1/x,y+1/y,z+1/z,x/y+y/x,y/z+z/y,z/x+x/z)");
in the 6-dimensional space.
This is a joint work with Takuya Ikuta.
***Michael Dobbins (GAIA, Postech) [#ze9edc62]
-Title:Reducing combinatorial to projective equivalence i...
-Abstract:
Determining if there is a polytope of any combinatorial t...
satisfies some given property is made difficult by the fa...
are polytopes with realization spaces that are homotopic ...
primary semialgebraic set. I will show how, for certain p...
this can be reduced to finding such realizations among pr...
equivalence classes of polytopes, which are much nicer sp...
application of this answers a question posed by Bernt Lin...
1971, that there does exist a polytope without an antipri...
***Aleksandar Jurišić (University of Ljubljana) [#q728cf69]
-Title:TOWER GRAPHS AND EXTENDED GENERALIZED QUADRANGLES
-Abstract:
Let &mimetex(\Gamma); be a complete multipartite graph wi...
and each part of size at least &mimetex(2);. For example,...
Let now &mimetex(\Gamma); be the point graph of a general...
We study a family of graphs, denoted by &mimetex({\cal F}...
properties
(i) their &mimetex(\mu);-graphs are complete multipartite,
(ii) there exist adjacent vertices &mimetex(x);, &mimetex...
This is a generalization of the study of extended general...
in it is intimately connected with even more general stud...
strongly regular graphs.
We report on our progress of the classification of the fa...
***Xiao-Dong Zhang (Shanghai Jiao Tong University) [#wec5...
-Title:[[The algebraic connectivity of graphs:http://comb...
-Abstract:
Let &mimetex(G); be a simple graph of order &mimetex(n); ...
&mimetex( L(G)=D(G)-A(G) ); be its Laplacian matrix, wher...
The the second smallest eigenvalue of &mimetex( L(G) ); ...
In this talk, we survey some new results and progress on ...
In particular, we present some relationships between the ...
connectivity and the graph parameters, such as the cliq...
the matching number, the independence number, the isoperi...
number, etc.
***Katsuhiro Ota (Keio University) [#mb37f86c]
-Title:[[Clique minors, chromatic numbers for degree sequ...
-Abstract:
For a given graph &mimetex(G);, let &mimetex(\chi(G)); an...
the chromatic number, and the maximum size of clique mino...
respectively.
The well-known Hadwiger's conjecture (1943) states that
&mimetex(\chi(G)\le h(G)); holds for every graph &mimetex...
for the graphs with &mimetex(\chi(G)\ge 7);.
In 2005, Robertson posed the "Hadwiger's conjecture for d...
For a graphical degree sequence &mimetex(D);, let &mimete...
denote the maximum &mimetex(\chi(G)); and &mimetex(h(G));...
among the graphs &mimetex(G); having degree sequence &mim...
Robertson's conjecture states that &mimetex(\chi(D)\le h(...
sequence &mimetex(D);.
This conjecture was recently confirmed by Dvoř&aacu...
by showing strongly that &mimetex(\chi(D)\le h'(D));, where
&mimetex(h'(D)); is the maximum size of topological cliqu...
having degree sequence &mimetex(D);.
In this talk, we give an alternative and very short proof...
Robertson's conjecture.
Also, we shall discuss the values of &mimetex(\chi(D));, ...
for some &mimetex(D);.
These results are based on a joint work with Guantao Chen...
***Yota Otachi (JAIST) [#h17d65f1]
-Title: [[The path-distance-width of hypercubes:http://co...
-Abstract:
The path-distance-width of a connected graph &mimetex(G);...
integer &mimetex(w); satisfying
that there is a nonempty subset of &mimetex(S \subseteq V...
number of the vertices
with distance &mimetex(i); from &mimetex(S); is at most &...
We present a general lower bound on the path-distance-wid...
and determine the path-distance-width of hypercubes by us...
We also discuss the applicability of the lower bound to o...
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