Talks that took place on or after 2022 can be found in researchmap.

1. Talks at Conferences
   • An analogue of t-designs in the association schemes of alternating bilinear forms, "Algebraic Combinatorics and Group Theory", Osaka City University Academic Extension Center, January 1985, pp.31-43.
   • t-designs in association schemes, 19th OSU-Denison Math. Conf. Denison University, Ohio, May 1986.
   • Distance-regular digraphs, 20th OSU-Denison Math. Conf. Denison University, Ohio, February 1988.
   • Nonsymmetric P- and Q-polynomial association schemes, NATO Advanced Institute on Orthogonal Polynomials, The Ohio State University, May 1989.
   • Splitting fields of association schemes, "Algebraic Combinatorics", Konan University, November 1989.
   • Orthogonal polynomials appearing in distance-regular digraph (in Japanese), "Algebraic Aspects of Special Functions", Nagoya Univerisity, December 1989. (abstract, report)
   • Davenport-Hasse theorem and cyclotomic association schemes, "Algebraic Combinatorics", Hirosaki University, July 1990. (pdf file)
   • Character table of Schur rings, Summer Seminar on Finite Groups, Kusatsu Seminar House, August 1990.
   • Distance-regular digraphs with Q-polynomial property, The Second Japan Conference on Graph Theory and Combinatorics, Hakone, August 1990.
   • Fusions in Association Schemes, "Algebraic Combinatorics", RIMS, Kyoto University, December 1990.
   • Orthogonality of subalgebras and Latin squares, 3rd Summer Seminar on Finite Groups, Kusatsu Seminar House, July 31, 1991. (pdf file)
   • Amorphous association schemes over Galois rings of characteristic 4, International Workshop on Algebraic Combinatorics, Vladimir, USSR, August 1991.
   • Characterization of the graphs of alternating forms and the graphs of quadratic forms over GF(2), Finite Geometry and Combinatorics, Second International Conference at Deinze, Belgium, June 1992.
   • A local characterization of the graphs of alternating forms, "Algebraic Combinatorics", RIMS, Kyoto University, December 1992.
   • Noncommutative fusion algebra associated to finite group actions, "Algebraic Combinatorics", RIMS, Kyoto University, March 1993.
   • Automorphism group of the graph of quadratic forms in characteristic 2, Finite Geometry and Designs, Shanghai, May 1993.
   • Group Theory Software GAP, Summer Seminar on Finite Groups, Kusatsu Seminar House, August 1993.
   • The graphs of alternating, symmetric, and quadratic forms, Association Schemes and Representation Theory, Oberwolfach, Germany, January 1994.
   • Geometry of the space of quadratic forms over GF(2^m), Algebra Symposium, Ehime University, July 1994.
   • An alternative construction of the graphs of quadratic forms, The First China-Japan International Symposium on Algebraic Combinatorics, Beijing, October 1994.
   • On perfect t-shift codes in Abelian groups, Algebraic Combinatorics and Related Topics, Ateneo de Manila University, December 1994.
   • Duality maps of finite abelian groups and their applications to spin models, "Algebraic Combinatorics", RIMS, Kyoto University, March 1995.
   • Realizability of parameter sets for association schemes in terms of vertex independence problem, "Algebraic Combinatorics", RIMS, Kyoto University, December 1995.
   • Regular subgroups of affine permutation groups and failure of factorization, Summer Seminar on Finite Groups, Kusatsu Seminar House, August 1995.
   • Cyclic Resolvability of PG(3,q), Summer Seminar on Finite Groups, Kusatsu Seminar House, August 1996.
   • Primitive trinomials and orthogonal arrays over GF(2), "Algebraic Combinatorics", International Christian University, July 1997.
   • Uniqueness of certain graphs embedded in the root systems E_6, E_7 and E_8, "Algebra and Computation", Tokyo Metropolitan University, October 1997.
   • Perfect 1-codes and tight 2-designs in Doob graphs, "Algebraic Combinatorics", Yamagata University, November 1997.
   • Tight 2-designs in Doob graphs, Summer Seminar on Finite Groups, Kusatsu Seminar House, July 1998.
   • Tight 2-designs and perfect 1-codes in Doob graphs, AMS sectional meeting, DePaul Univ., Chicago, September 1998.
   • Hermitian modular forms constructed from certain codes, "Algebraic Combinatorics and Quadratic Forms", Yamagata University, November 1998.
   • Applications of the arithmetic of finite fields to finite projective geometries via the action of the Singer cycle, Conference in Algebra, Ateneo de Manila University, December 3, 1998. Transparencies
   • A classification of exceptional graphs with smallest eigenvalue -2 represented in the root system E_8, Kyushu Sectional Meeting of Mathematical, Society of Japan, Fukuoka Kyoiku University, February 1999.
   • Hermitian modular forms obtained from certain codes over a finte ring Annual Meeting of the Mathematical Society of Japan, Gakushuin University, March 1999.
   • Flag-transitive 2-designs, The Third Shanghai Conference on Designs, Codes and Finite Geometries, Shanghai, May 16, 1999. Transparencies
   • Automorphism Groups of Codes and Lattices, Summer Seminar on Finite Groups, Kusatsu Seminar House, August 1999.
   • A classification of maximal graphs represented in the root system E_8, Geometric and Algebraic Combinatorics, an international conference in honour of J.J. Seidel on the occasion of his 80th birthday, Oisterwijk, The Netherlands, August 1999.
   • Flag-Transitive 2-(v,4,1) Designs, "Combinatorial Designs and Their Applications" Tsukuba International Conference Center, October 8, 1999. Transparencies
   • Hermitian modular forms constructed from invariants of a finite group, "Algebra and Computation", Tokyo Metropolitan University, October 1999
   • A mass formula for Type II codes over finite fields of characteristic Two, XXVth Ohio State-Denison Mathematics Conference, The Ohio State University, May 18, 2000. Transparencies
   • Symmetric Association Schemes Derived from Nonsymmetric Bipartite Commutative Association Schemes, Com2Mac Conference on Association Schemes, Codes and Designs, POSTECH, July 2000. Transparencies
   • Mass formula for higher weight enumerators of doubly-even self-dual binary codes, Algebraic Combinatorics, Monster and Vertex Operator Algebras, University of California, Santa Cruz, July 2000
   • A generalization of the mass formula for self-dual codes, Annual Meeting of the Mathematical Society of Japan, Kyoto University, September 2000. Abstract (tex, dvi) Transparencies (tex, pdf)
   • Distance-Regular Graphs Related to the Binary Golay Code and Their Spherical Representation, Japan-France Workshop on Combinatorics, Zao Echo Hotel, October 2000. slides (pdf), abstract (tex)
   • On the enumeration of self-dual codes, "Algebraic Geometry, Number Theory, Coding Theory and Cryptography", University of Tokyo, November 2000. report (dvi)
   • Spherical 5-designs obtained from the unitary group U_{2m}(2), "Codes, Lattices, Vertex Operator Algebras and Finite Groups", RIMS, Kyoto University, February 2001
   • The biweight enumerators of doubly-even self-dual binary codes and the root system E_8, Ateneo de Manila University, February 2001.
   • The association scheme of injections, Summer Seminar on Finite Groups, Kusatsu Seminar House, July 2001. report (pdf)
   • Type II codes over F_2^r, 14th Applied Algebra, Algebraic Algorithms and Error Correcting Codes, RMIT University, Melbourne, Australia, November 2001.
   • Nonexistence of tight spherical designs, The 19th Symposium on Algebraic Combinatorics, Kumamoto University, July 2002. slides (DVI file), report (DVI file)
   • The nonexistence of some tight spherical designs, Geometric and Algebraic Combinatorics 2, Oisterwijk, The Netherlands, August 2002.
   • MacWilliams identities, Delsarte inequalities and Terwilliger algebras, "Designs, Codes, Graphs and their Links", RIMS, Kyoto University, September 2002.
   • Self-dual [40,20,8] codes with covering radius 7, Arithmetic and Combinatorics, Luminy, France, September 26, 2002. slides
   • Non-antipodal spherical 5-designs constructed by finite unitary groups, Workshop on spherical designs, Univ. Geneva, Switzerland, October 2002.
   • Mass formula for the Jacobi weight enumerator polynomials of binary self-dual codes, "Combinatorial Number Theory and Algebraic Combinatorics", Yamagata University, November 2002.
   • Nonexistence of Tight Spherical Designs, "Statistics, Combinatorics and Geometry", Institute for Statistical Mathematics, March 2003.
   • Extremal Configurations in Dimension 48 The Second East Asian Conference on Algebra and Combinatorics, Kyushu University, November 21, 2003. (PDF file) (complete archive)
   • Extremal lattices and spherical designs, Com2MaC Conference on Association Schemes, Codes and Designs, July 21, 2004, Pusan National University. slides (PDF file)
   • Association schemes and spherical designs, Com2MaC Workshop on Distance-Regular Graphs and Finite Geometry, Pusan National University,
     July 24, 2004. slides (PDF file) report (LaTeX file)
   • Singer difference sets and difference system of sets, "Experimental Designs and Their Applications", Ise, November 18, 2004. slides (PDF file)  report (PDF file)
   • Difference systems of sets over finite projective spaces, Mini-Workshop on Combinatorics, Kyushu University, March 7, 2005.
   • Spherical designs and extremal lattices, Conference on Groups and Lie Algebras, Sophia University, March 10, 2005.
   • Extremal problems related to binary singly even self-dual codes ,
     "Combinatorial Designs and Their Applications",
     RIMS, Kyoto University
     August 4, 2005.slides (PDF file)
   • Extremal lattices and spherical designs, Geometric and Algebraic Combinatorics 3, Oisterwijk, the Netherlands,
     August 15, 2005.slides (PDF file)
   • Self-orthogonal designs, "Algebraic Combinatorics and Related Topics", RIMS, Kyoto University October 4, 2005.report (PDF file)
   • Covering radii of extremal binary doubly even self-dual codes, Asian Symposium on Computer Mathematics, KIAS, Seoul, Korea, December 10, 2005. slides (PDF file) slides (LaTeX file, requires beamer package)
   • Combinatorial structures derived from extremal even unimodular
     lattices, Algebra and Combinatorics 2006, Ateneo de Manila University, Quezon City, the Philippines, April 1, 2006. slides (PDF file)
   • Spherical designs (An introduction to designs in spheres and complex projective spaces), "Combinatorics and Its Application to Information Sciences", RIMS, Kyoto University, September 14, 2006. slides (PDF file) and resume (PDF file)
   • On graphs with complete multipartite mu-graphs, Korea-Japan Workshop on Algebra and Combinatorics, Pusan National University, February 10, 2007. slides
   • Spherical designs, ISM Symposium on Stochastic Models and Discrete Geometry, Institute for Statistical Mathematics, February 27, 2007. slides
   • Codes and lattices of Hadamard matrices, "Design Theory and Its Applications", RIMS, Kyoto University, June 12, 2007. slides, report.
   • On graphs with complete multipartite mu-graphs, 6th Slovenian Conference on Graph Theory, Bled, Slovenia, June 25, 2007. slides
   • Mass formula for codes, Summer Seminar on Finite Groups, Kusatsu Seminar House, August 3, 2007. report.
   • Classification of ternary extremal self-dual codes of length 28, 7th Symposium on Algebra and Computation, Tokyo Metropolitan University, December 5, 2007. slides
   • Spherical designs obtained from certain non-unimodular integral lattices, Mini-symposium on Algebraic Combinatorics, Kobe Gakuin University, March 21, 2008. slides
   • On some cyclotomic association schemes and strongly regular graphs, Geometric and Algebraic Cominatorics 4, Oisterwijk, the Netherlands, August 18, 2008. slides, talk
   • Steiner quadruple systems extending affine triple systems, RIMS, Kyoto University, October 14 and 16, 2008.
   • Mass formula for self-dual codes, Mini-workshop in Algebraic Combinatorics, National Cheng Kung University, Tainan, Republic of China, November 29, 2008. slides
   • Steiner quadruple systems with abelian regular automorphism group, RIMS, Kyoto University, January 7, 2009. slides
   • Twisted Grassmann graph is the block graph of a design, Summer School on Designs and Codes, Hills Sunpia Yamagata, June 21, 2009. poster
   • Frames of the Leech lattice and their applications, The 54th Algebra Symposium, Meiji University, August 6, 2009. slides
   • The twisted Grassmann graph is the block graph of a design, Japan-Korea Workshop on Algebra and Combinatorics, Kyushu University, August 27, 2009.
   • Rains' algorithm for classifying self-dual Z_4-codes with given residue, One Day Workshop on Algebraic Combinatorics, Institute of Mathematics, Academia Sinica, October 14, 2009. slides
   • On the classification of self-dual Z_k-codes, the Twelfth IMA International Conference on Cryptography and Coding, Royal Agricultural College, United Kingdom, December 15, 2009. slides
   • Triply even binary codes, lattices and framed vertex operator algebras, Algebraic and Geometric Combinatorics, Gyeongju, Korea, July 12, 2010. slides
   • Graphs with smallest eigenvalue -2 and root systems, Kyushu University, October 9, 2010. slides demo.txt
   • An infinite family of weighing matrices, Hadamard matrices and related algebraic combinatorics, Kobe Gakuin University, December 12, 2010. slides
   • Towards the classification of 4-frames in the Leech lattice, "Research into Vertex Operator Algebras, Finite Groups and Combinatorics," Kyoto University, December 13, 2010. slides
   • Error-correcting codes appearing in pure mathematics, Sophia University, December 21, 2010. slides (in Japanese)
   • Accumulation points of the smallest eigenvalues of graphs, Analysis on Graphs in Sendai 2011, Tohoku University, February 21, 2011. slides
   • Binary codes related to the moonshine vertex operator algebra, Mathematical Society of the Philippines Annual Convention, University of Santo Tomas, Manila, the Philippines, May 21, 2011. slides
   • Variations of two results of Jungnickel-Tonchev on projective spaces, Geometric and Algebraic Combinatorics 5, Oisterwijk, The Netherlands, August 15, 2011. slides
   • Constructive enumeration of self-dual codes using tools from permutation groups, International Conference on Coding and Cryptography, Ewha Womans University, Seoul, Korea, August 25, 2011. slides
   • Frames of the Leech lattice, Workshop on Algebraic Combinatorics, Shanghai Jiao Tong University, Shanghai, China, September 15, 2011. slides
   • Smallest eigenvalues of graphs and root systems of type A, D and E, Topics in the Theory of Weyl Groups and Root Systems, in honor of Professor Jiro Sekiguchi on his 60th birthday, University of Tokyo, September 22, 2011. slides (only the first part; the second part was a blackboard talk.)
   • Wilson's bijection and upper bounds on cyclotomic numbers, Nagoya University, November 19, 2011. slides
   • Super Catalan numbers and Krawtchouk polynomials, Combinatorics Seminar, Kyushu University, November 26, 2011. slides
   • Graphs with complete multipartite $\mu$-graphs, Incidence Geometry and Buildings, University of Ghent, February 6, 2012. slides
     
   • Graphs with Smallest Eigenvalue at least -3, The 5th International Workshop on Optimal Network Topologies, Institut Teknologi Bandung, Indonesia, July 27, 2012. slides
   • Complex Hadamard matrices contained in a Bose-Mesner algebra, The 2nd Japan-Taiwan Conference on Combinatorics and Its Applications, Nagoya University, November 10, 2012. slides
   • Complex Hadamard matrices contained in a Bose-Mesner algebra, Combinatorics Seminar Hakata Workshop, Fukuoka, January 26, 2013. slides
   • On the image of certain rational mapping related to inverse orthogonal matrices, Workshop on Algebraic Combinatorics, Kobe Gakuin University, March 7, 2013.
   • Complex Hadamard matrices and 3-class association schemes, The 30th Algebraic Combinatorics Symposium, Shizuoka University, June 26, 2013. slides
   • Linear codes obtained from combinatorial designs, Discrete Mathematics and Applications, Yamagata, August 9, 2013. slides
   • Complementary Ramsey numbers, JCDCGG, Tokyo University of Science, September 17, 2013 slides
   • Twisted symplectic polar graphs, Workshop on Algebraic Combinatorics, Hebei Normal University, November 20, 2013. slides
   • Twisted symplectic polar graphs, Colloquium on Galois geometry to the memory of Frederic Vanhove, Ghent University, February 28, 2014. slides
   • Godsil-McKay switching and twisted Grassmann graphs, The Eighth Shanghai Conference on Combinatorics, Shanghai Jiao Tong University, May 27, 2014. slides
   • On the smallest eigenvalues of the line graphs of some trees, Nantong Workshop on Combinatorial Theory and Coding Theory, Nantong University, May 29, 2014. slides
   • Complex Hadamard matrices contained in a Bose-Mesner algebra, Algebraic Combinatorics: Spectral Graph Theory, Erdos-Ko-Rado Theorems and Quantum Information Theory, University of Waterloo, June 27, 2014. slides
   • Generalized tensor products and related constructions, Workshop on Algebraic Design Theory and Hadamard Matrices, University of Lethbridge, July 10, 2014. slides
   • Godsil-McKay switching and twisted Grassmann graphs, Designs, Codes, Graphs and Related Areas, Kyoto University, July 23, 2014. slides
   • Extremal type II Z4-codes of length 24 and triply even binary codes of length 48, ICM2014 Satellite Conference on Algebraic Coding Theory, Ehwa Womans University, Seoul, Korea, August 12, 2014. slides
   • A parametric family of complex Hadamard matrices, Workshop on Statistical Designs and Related Combinatorics, Kinosaki International Arts Center, December 15, 2014. slides
   • Self-Orthogonal Codes and Hadamard Matrices, Algebraic Design Theory and Related Topics, Kumamoto University, January 11, 2015. slides
   • A remark on Turyn's construction of conference matrices, Finite Geometry and Designs, Tokyo University of Science, March 6, 2015. slides
   • Self-orthogonal designs, The 32nd Algebraic Combinatorics Symposium, Kanazawa, June 22, 2015. slides, report
   • Richard Thompson's group F, Summer Seminar on Finite Groups, Kusatsu Seminar House, August 3, 2015. report
   • Self-orthogonal designs and equitable partitions, Algebraic Combinatorics Workshop, Zhejiang University, September 20, 2015. slides
   • Self-orthogonal designs and equitable partitions, Towards new development of mathematics via computational algebra system, RIMS, Kyoto University, September 30, 2015. slides
   • Covering radii and shadows of binary self-dual codes, Algebra and Computation, Tokyo Metropolitan University, December 15, 2015. slides
   • On a lower bound on the Laplacian eigenvalues of a graph, The Japanese Conference on Combinatorics and its Applications, Kyoto University, May 22, 2016. slides
   • Triply even codes obtained from some graphs and finite geometries, Graphs and Groups, Spectra and Symmetries, Novosibirsk, Russia, August 21, 2016. slides
   • Group theoretic aspects of the theory of association schemes, International Workshop on Algebraic Combinatorics, Anhui University, Hefei, China October 29, 2016. slides
   • Nonexistence of a quasi-symmetric 2-(37,9,8) design, Design of experiments, codes and related combinatorial structures, Akiu Resort Hotel Crescent, Sendai, November 29, 2016. slides
   • Complementary Ramsey numbers, graph factorizations and Ramsey graphs, 1st Tohoku-Bandung Bilateral Workshop, Tohoku University, Sendai, May 30, 2017. slides
   • A matrix approach to Yang multiplication, 5th Workshop on Real and Complex Hadamard Matrices and Applications, Alfred Renyi Institute of Mathematics, Budapest, Hungary, July 10, 2017 slides
   • Butson-Hadamard matrices in association schemes of class 6 on Galois rings of characteristic 4, Workshop on Group Theory and Algebraic Combinatorics, Novosibirsk State University, Novosibirsk, Russia, July 17, 2017 slides
   • A matrix approach to Yang multiplication, International Conference and PhD-Master Summer School Groups and Graphs, Metrics and Manifolds, Ural Federal University, Yekaterinburg, Russia, Part I, July 24, 2017, slides Part II, July 25, 2017. slides
   • Weight enumerators of binary singly even self-dual codes, Japanese Conference on Combinatorics and its Applications, Kumamoto University, August 18, 2017. slides
   • Imprimitive permutation groups which are nearly multiplicity-free, International Workshop on Bannai-Ito Theory, Zhejiang University, Hangzhou, China, November 24, 2017. slides
   • The Reed-Muller code RM(1,4), the Barnes-Wall lattice BW(16), and graphs with smallest eigenvalue -3, The 2nd Tohoku-Bandung Bilateral Workshop, Extremal Graph Theory, Algebraic Graph Theory and Mathematical Approach to Network Science, Tohoku University, June 5, 2018. slides
   • A graph with smallest eigenvalue -3 related to the shorter Leech lattice, Hakata Workshop Summer Meeting, Fukuoka, June 16, 2018. slides
   • Complementary Ramsey numbers and Ramsey graphs, The 7th ICMNS, Institut Teknologi Bandung, Indonesia, November 3, 2018 slides
   • A variation of Godsil-McKay switching, An International Workshop on Algebraic Combinatorics, Anhui University, Hefei, China, November 22, 2018 slides
   • Krein parameters of fiber-commutative coherent configurations, Taipei International Workshop on Combinatorics and Graph Theory, Academia Sinica, Taipei, Taiwan, February 23, 2019 slides
   • Krein conditions for coherent configurations, Ural Workshop on Group Theory and Combinatorics, Ural Federal University, Yekaterinburg, Russia, March 23, 2019 slides
   • Krein parameters of fiber-commutative coherent configurations, The 9th Slovenian International Conference on Graph Theory, Bled, Slovenia, June 27, 2019 slides
   • Hoffman's Limit Theorem, The International Conference and PhD-Master Summer School on Groups and Graphs, Designs and Dynamics, Yichang, China, August 20, 2019 slides
   • Digraphs with Hermitian spectral radius at most 2, JCCA 2019, National Institute of Technology, Miyakonojo, August 28, 2019 slides
   • Hermitian adjacency matrices of digraphs and root lattices over the Gaussian integers, International Conference on Algebraic Combinatorics, Henan Polytechnic University, Jiaozuo, China, September 22, 2019 slides
   • Equiangular lines in Euclidean spaces, Frontiers in Mathematical Science Research Workshop, Shanghai University, Shanghai, China, September 28, 2019 slides
   • Extremal finite sets in spheres and projective spaces, Indo-Japan joint workshop on quantum computation and quantum information, Indian Statistical Institute, Kolkata, India, January 6, 2020. slides
   • The regular two-graph on 276 vertices revisited, JCCA 2020 (online) August 20, 2020 slides
   • The regular two-graph on 276 vertices revisited, Ural Workshop on Group Theory and Combinatorics (online) August 24, 2020 slides
   • Neighbor-balanced bijections of hypercubes, The 4th Workshop on Algebraic Graph Theory (online) March 1, 2021 slides
2. Other Talks
   • Duality in association schemes, Colloquium, Tsukuba University, May 1991.
   • The character table of an S-ring with modular invariance, Colloquium, Kyushu University, September 1991.
   • Duality of symmetric bilinear forms and alternating bilinear forms over finite fields of characteristic 2, Colloquium, Kumamoto University, February 1994.
   • Introduction to Algebraic Combinatorics, "Summer School on Algebraic Combinatorics", Matsuyama, July 1994.
   • Multiplicity-free finite groups, Colloquium at University of Philippines, February 1995.
   • The geometry of orthogonal groups over finite fields, Colloquium at De La Salle University, Manila, February 1995.
   • Introduction to binary codes, Colloquium at University of Philippines, Baguio, March 1997.
   • Caps in finite projective spaces, "Gauss Sums, Jacobi Sums and Their Applications to Combinatorics", RIMS, Kyoto University, December 1997.
   • Flag-transitive Steiner systems, Combinatorics Seminar, Iowa State University, September 1998.
   • Graphs related to exceptional root systems, Colloquium at Iowa State University, September 1998.
   • Nonsymmetric fission of symmetric bipartite association schemes Mini-Workshop on Algebraic Combinatorics Kyushu University, March 1999.
   • Introduction to Association schemes, "Summer School in Algebraic Combinatorics", Shikanoshima, June 1999.
   • Construction of doubly-even self-dual binary codes by Harada-Kimura-Tonchev operations, Colloquium at Michigan Technological University, May 15, 2000. slides
   • Binary self-dual codes and orthogonal groups, Colloquium at University of North Texas, May 2000.
   • The biweight enumerators of doubly-even self-dual binary codes and the root system E_8, Colloquium at University of Waterloo, August 2000.
   • Distance-regular graphs related to the binary Golay code and their spherical representation, Colloquium at Bowling Green State University, September 2000.
   • Introduction to Finite Geometries, "Algebra and Computation", Tokyo Metropolitan University, November 2001.
   • Codes and invariant polynomials and modular forms, Spring Conference on Modular Forms, Hamanako, February 2002.
   • Some topics related to the root system E_8, Colloquium, Tohoku University, May 2003. notes (jpg file)
   • Extremal lattices and spherical designs, Colloquium, Kyushu University, June 16, 2004.
   • Extremal self-dual binary codes, Colloquium, Kinki University, December 16, 2004.
   • On the generating property of even unimodular lattices, Group Theory Seminar, Hokkaido University, May 24, 2006.
   • Binary and ternary codes of Hadamard matrices, Kunitachi One Day Seminar on Design Theory, Hitotsubashi University, February 19, 2007. contents (pdf file)
   • Introduction to spherical designs, The 1st Workshop on Forum on Applied Mathematics, Tohoku University, September 4, 2007. slides
   • Non-amorphous association schemes in which all nontrivial relations are strongly regular, The 22nd PNU-POSTECH Algebraic Combinatorics Seminar, Pusan National University, November 24, 2007. summary (corrected, 2007-12-05)
   • Twisted Grassmann geometry, Matsue seminar, Shimane University, October 21, 2009.
   • Linear, quadratic, and cubic forms over the binary field, Math. Club at POSTECH, October 28, 2009. slides
   • Triply even binary codes and their application to framed vertex operator algebras, Colloquium, POSTECH, Korea, October 30, 2009. slides
     
   • Generalized Hadamard matrices, The 34th PNU-PMI Algebraic Combinatorics, Pusan National University, Korea, October 31, 2009.
   • A characterization of quasi-line graphs, Combinatorics Seminar, Kyushu University, July 10, 2010, slides
   • The moonshine vertex operator algebras and binary codes, The 54th Encounter with Mathematics, Chuo University, October 2, 2010. slides (in Japanese)
   • Weighing matrices of order $2(q+1)$ and weight $q$, Discrete Mathematics Seminar in Oyama, Oyama College of Technology, November 23, 2010. slides
   • Automorphisms and isomorphism testing for codes over the ring of integers modulo 4, Kinki University, December 20, 2010.
   • Computers and mathematics, a personal view, Sophia Mathematics, Sophia University, March 5, 2011.
   • Hadamard graphs and their directed analogue, AGC seminar, POSTECH, April 1, 2011. memo
   • The twisted Grassmans graph is a block graph of a design, Ateneo de Manila University, May 24, 2011. memo
   • The total number of reversals for generously transitive permutation groups, University of the Philippines, May 25, 2011.
   • Upper bounds on cyclotomic numbers, Kinki University, November 16, 2011.
   • Butson-Hadamard matrices in association schemes of class 6 on Galois rings of characteristic 4, Combinatorics Seminar, Shanghai Jiao Tong University, Shanghai, China, November 17, 2017. slides
   • Turyn's construction of conference matrices, Combinatorics Seminar, ITB, Bandung, Indonesia, March 22, 2018. slides
   • Oriented covers of the triangular graphs, Combinatorics Seminar, Beijing Normal University, China, March 30, 2018. slides
   • Quasi-symmetric 2-(56,16,18) designs constructed from the dual of the quasi-symmetric 2-(21,6,4) design as a Hoffman coclique, Combinatorics Seminar, China University of Geoscience in Beijing, China, March 31, 2018. slides
   • A variation of Godsil-McKay switching, Combinatorics Seminar, Krasovskii Institute of Mathematics and Mechanics, Ural Branch of Russian Academy of Sciences, March 26, 2019. notes (blackboard talk)
   • Hoffman's limit theorem, East China Normal University, Shanghai, China, September 26, 2019. slides
   • Maximality of Seidel matrices and switching roots of graphs, Ural Seminar on Group Theory and Combinatorics (online) February 16, 2021 slides
3. Series of Lectures
   • The geometry of orthogonal groups over finite fields, Ateneo de Manila University, February 1995.
   • Introduction to binary codes, Ateneo de Manila University, February 1997.
   • Fibonacci sequences and shift register sequences, Kumamoto University, December 1997.
   • Permutations, Kyushu University, August 1999.
   • Yamagata University, Chiba University(2000)
   • Kyushu University, International Christian University(2004)
   • Hokkaido University (2006)
   • Codes Generated by Designs, and Designs Supported by Codes, CIMPA-UNESCO-MESR-MINECO-THAILAND research school, Graphs, Codes, and Designs, Ramkhamhaeng University, May 2013. Printed version (part I, part II, part III), presentation (part I, part II, part III).
   • Binary codes of t-designs and Hadamard matrices, Asian Academic Seminar, The University of Tokyo, November 8, 2013. slides
   • Grassmann graphs, Hebei Normal University, November 21, 2013. handout, detailed notes
   • Introduction to association schemes, Summer School on Algebraic Combinatorics, June 2014. part I, part II, handout.
   • Permutation representations of finite groups and association schemes, G2R2-Summer School, Novosibirsk State University, August 2018. Lecture 1, Lecture 2, Lecture 3, Lecture 4, Lecture 5, Lecture 6, Lecture 7, Lecture 8, Problems.
   • Introduction to algebraic combinatorics, ITB, Bandung, Indonesia, November 5 and 8, 2018. part I, part II, exercises.

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