Skip to content Home Talks 2026 2025 November 7, 2025: 25th Yongbong Math Education Research Workshop, Chonnam National University, Gwangju, Korea.Proofs in the age of AI and Internet (AI와 인터넷 시대의 증명) November 6, 2025: Gwangju Combinatorics Seminar, GIST, Gwangju, Korea.The Erdős-Pósa property for circle graphs as vertex-minors October 30, 2025: Bertinoro Workshop on Algorithms and Graphs (BWAG 2025, October 26-31) , Bertinoro, Italy.The Erdős-Pósa property for circle graphs as vertex-minors September 23, 2025: Discrete Analysis Seminar , Yonsei University, Seoul, Korea.The Erdős-Pósa property for circle graphs as vertex-minors August 29, 2025: Discrete Math Seminar , IBS Discrete Mathematics Group, Daejeon, Korea.The Erdős-Pósa property for circle graphs as vertex-minors June 27, 2025: 2025 Youngnam Mathematical Society-Chungcheong Mathematical Society Joint Annual Meeting, Kyungpook National University, Daegu, Korea.Coloring t-perfect graphs June 21, 2025: Symposium on Directed and Undirected Graphs (June 20-25), Nankai University, Tanjin, China.Coloring t-perfect graphs May 1, 2025: Colloquium: Challenging Mathematica Problems, KIAS, Seoul, Korea.Coloring t-perfect graphs May 1, 2025: 첨단과학기술진로탐색 강연, Seoul Science High School, Seoul, Korea.Stories on perfect graphs (완벽한 그래프 이야기) March 13, 2025: Colloquium, Department of Mathematics, Chungbuk National University, Cheongju, Korea.Coloring t-perfect graphs January 15, 2025: Theoretical Computer Science Seminar , Jagiellonian University, Kraków, Poland.Linear bounds on treewidth in terms of excluded planar minors January 9, 2025: Oberwolfach Workshop Graph Theory (January 5-10), Mathematisches Forschungsinstitut Oberwolfach, Oberwolfach, Germany.Bounding the chromatic number of t-perfect graphs 2024 December 11, 2024: Joint Meeting of the NZMS, AustMS and AMS (December 8-13) , University of Auckland, Auckland, New ZealandBounding the chromatic number of t-perfect graphs October 21, 2024: 2024 X-STEM놀라운 과학: STEM 과학 탐험 , Daejeon Convention Center, Daejeon, Korea.Mathematical proofs in the age of AI인공지능시대의 수학증명 October 2, 2024: “New Perspectives in Colouring and Structure ” workshop (September 29-October 4), Banff International Research Station, Banff, Alberta, Canada.Bounding the chromatic number of t-perfect graphs September 25, 2024: Combinatorics Seminar, Hanyang University, Seoul, Korea. September 5, 2024: Math Seminar , GIST, Gwangju, Korea.Mathematical proofs in the age of AI and the internetAI와 인터넷 시대의 수학 증명 June 24, 2024: 3rd Korea-China Young Scholar’s Symposium on Discrete Mathematics (June 24-27), UTop Ubless Hotel Jeju, Jeju, Korea.Linear bounds on treewidth in terms of excluded planar minors 2023 November 16, 2023: 2nd Workshop on Logic, Graphs, and Algorithms (LoGAlg 2023) (November 15-17), University of Warsaw, Warsaw, Poland.Survey on vertex-minor obstructions and related parameters of graphs October 16, 2023: 2023 Vertex-Minor Workshop (October 15-20), SONO Belle Jeju, Jeju, Korea. September 8, 2023: East-Asia Workshop on Operations Research, Combinatorial Optimization and Algorithms (September 8-10), National Tsing Hua University, Hsinchu, Taiwan.Γ-graphic delta-matroids and their applications on variants of maximum spanning tree problems August 22, 2023: Tuesday Special Lecture화요특강 , Seoul National University Bundang Hospital , Seongnam, Korea.Applications of Discrete Mathematics이산수학의 쓰임새 August 9, 2023: 28th KIAS Combinatorics Workshop , KIAS, Seoul, Korea.Reuniting 𝜒-boundedness with polynomial 𝜒-boundedness March 30, 2023: Colloquium, Department of Mathematics, Kyunghee University , Seoul, Korea.Building the hierarchy of graph classes January 28, 2023: Workshop on Graph Coloring and Related Topics (January 28-29), Konkuk University, Seoul, Korea.Improper colorings regarding Hadwiger’s conjecture 2022 December 19, 2022: 2022 BrainLink – Combinatorial Algebraic Geometry2022 우수연구자교류지원 기술교류회 – 조합 대수기하학 국제교류회 , Korean Federation of Science and Technology Societies한국과학기술단체총연합회 , Sheraton Grand Incheon Hotel, Incheon, Korea.Γ-graphic delta-matroids and their applications December 5, 2022: Sejong Academy of Science and Arts세종과학예술영재학교 , Sejong, Korea. December 2, 2022: International Conference on Matrix Theory with Applications to Combinatorics, Optimization and Data Science (December 1-5), Seogwipo KAL Hotel Jeju, Jeju, Korea.Γ-graphic delta-matroids and their applications December 1, 2022: Colloquium , Department of Mathematics, Hanyang University, Seoul, Korea.Building the hierarchy of graph classes November 11, 2022: Combinatorics Today Series 2022 , Institut Teknologi Bandung, Online, Indonesia.Building the hierarchy of graph classes November 4, 2022: Fields Symposium , POSTECH, Pohang, Korea.A combinatorial path taken by June E Huh October 20, 2022: 2022 Global KMS International Conference (October 18-21), Seoul, Korea.Building the hierarchy of graph classes August 19, 2022: Workshop on Graph Theory and Combinatorics in Memory of Robin Thomas (August 19-21), Georgia Institute of Technology, Atlanta, USA.Building the hierarchy of graph classes July 25, 2022: 8th Czech-Slovak International Symposium on Graph Theory, Combinatorics, Algorithms and ApplicationsDedicated to the Memory of Robin Thomas (July 25-29), Charles University, Prague, Czech.Building the hierarchy of graph classes July 23, 2022: Special Lecture, Busan National Science Museum, Busan, Korea. June 23, 2022: Seymour 70+x workshop (June 20-24), ENS de Lyon, Lyon, France.Independent domination of graphs with bounded maximum degree May 31, 2022: Korea-Taiwan-Vietnam Joint Seminar in Combinatorics and Analysis Building the hierarchy of graph classes March 18, 2022: 39th International Symposium on Theoretical Aspects of Computer Science (STACS 2022) Obstructions for matroids of path-width at most k and graphs of linear rank-width at most k March 8, 2022: Graphs and Matroids Seminar , The Matroid Union, Online.Obstructions for matroids of path-width at most k and graphs of linear rank-width at most k February 28, 2022: Discrete Math Seminar , IBS Discrete Mathematics Group, Daejeon, Korea.Obstructions for matroids of path-width at most k and graphs of linear rank-width at most k February 25, 2022: SCMS Combinatorics Seminar , Shanghai Center for Mathematical Sciences, Fudan University, Shanghai, China.Independent domination of graphs with bounded maximum degree February 22, 2022: 24th KIAS Combinatorics Workshop (February 22-24), Shilla Stay Haeundae, Busan, Korea.Building the hierarchy of graph classes February 17, 2022: Industrial Mathematics Colloquium산업수학콜로퀴움 , NIMS ICIM, Suwon, Korea.Building the hierarchy of graph classes January 6, 2022: Oberwolfach workshop on Graph Theory (January 2-8), Mathematisches Forschungsinstitut Oberwolfach (MFO), Oberwolfach, Germany.Obstructions for matroids of path-width at most k and graphs of linear rank-width at most k 2021 November 11, 2021: 2021 China-Korea Young Scholars’ Symposium on Discrete Mathematics, Statistics and Optimization, Tianjin-SIAM / Nankai University / The State University of New York, Korea / Tianjin Science and Technology Association, Online, Korea & China.Obstructions for graphs of linear rank-width at most k November 4, 2021: AlGCo Seminar , Département Informatique, LIRMM, Montpellier, France.Obstructions for matroids of path-width at most k and graphs of linear rank-width at most k October 8, 2021: Graz Combinatorics Seminar , Technical University of Graz, Graz, Austria. Online.Obstructions for graphs of linear rank-width at most k July 22, 2021: Minisymposium on Graph Structure, SIAM Conference on Discrete Mathematics (July 20-23), Online, Spokane, USA.Obstructions for bounded shrub-depth and rank-depth of graphs April 20, 2021: Discrete Math Seminar , IBS Discrete Mathematics Group, Daejeon.What is an isotropic system? April 9, 2021: Bordeaux Graph Seminar, LaBRI, Bordeaux, France.A unified half-integral Erdős-Pósa theorem for cycles in graphs labelled by multiple abelian groups 2020 December 14, 2020: The 31st International Symposium on Algorithms and Computation (ISAAC’20), Online, Hong Kong . (December 14-18) (invited talk)How to decompose a graph into a tree-like structure November 27, 2020: 2020 KEDI Job Training for teachers in charge of gifted education영재교육 담당교원 전문성강화 직무연수 , Daegu, Korea. (Online). November 5, 2020: Séminaire virtuel de théorie des graphes et combinatoire en Rhône-Alpes et Auvergne , France. (Online).Obstructions for bounded shrub-depth and rank-depth of graphs April 21, 2020: Discrete Math Seminar , IBS Discrete Mathematics Group, Daejeon. March 19, 2020: New Perspectives in Colouring and Structures , Banff International Research Station, Banff, Canada. (Online). (March 15-20)3-degenerate induced subgraphs of a planar graph 2019 October 27, 2019: 2019 KMS Annual Meeting, Hongik University, Seoul. (October 25-27) The Erdős-Hajnal property for graphs with no fixed cycle as a pivot-minor October 19, 2019: The 4th IBS-CGP Public Lecture제4회 IBS 기하학 수리물리 연구단 수학 문화 강연 , IBS Center for Geometry and Physics, Pohang. September 24, 2019: The 9th Workshop on Graph Classes, Optimization, and Width Parameters (GROW 2019) , TU Wien, Vienna (September 23-26)Branch-depth: Generalizing tree-depth of graphs August 1, 2019: 2019 IBS Summer Research Program on Algorithms and Complexity in Discrete Structures , IBS Discrete Mathematics Group, DaejeonBranch-depth: Generalizing tree-depth of graphs July 4, 2019: Graph Colouring: from Structure to Algorithms , Dagstuhl Workshop, Dagstuhl, Germany.The Erdős-Hajnal property for graphs with no fixed cycle as a pivot-minor June 6, 2019: International Conference on Network Games, Tropical Geometry, and Quantum Communication , Berlin Mathematics Research Center MATH+, Zuse Institute of Berlin, Berlin, Germany. May 28, 2019: Mini-symposium “structural graph theory” , CanaDAM 2019 , Vancouver, Canada.The Erdős-Hajnal property for graphs with no fixed cycle as a pivot-minor May 1, 2019: Structural Graph Theory and Graph Coloring , Tsinghua Sanya International Mathematics Forum , Sanya, China. (April 29-May 3)Branch-depth: Generalizing tree-depth of graphs April 20, 2019: Plenary Lecture, 2019 KMS Spring Meeting , Kangwon National University, Chuncheon.How to decompose a graph into a tree-like structure April 16, 2019: PCS Seminar , Center for Theoretical Physics of Complex Systems, Institute for Basic Science, Daejeon.How to decompose a graph into a tree-like structure March 31, 2019: 2019 Spring Jinhua Workshop on Graph Theory , Zhejiang Normal University, Jinhua, China.Branch-depth: Generalizing tree-depth of graphs March 28, 2019: Colloquium, GIST College , GIST, Gwangju. March 22, 2019: Special Session on Structural Graph Theory, AMS Spring Central and Western Joint Sectional Meeting , University of Hawaiʻi at Mānoa, Hawaii, USA.Classes of graphs with no long cycle as a vertex-minor are polynomially 𝜒-bounded March 15, 2019: 대구과학고 아카데미 강연, Daegu Science High School, Daegu. February 21, 2019: Taipei International Workshop on Combinatorics and Graph Theory , Institute of Mathematics, Academia Sinica, Taipei, TaiwanClasses of graphs with no long cycle as a vertex-minor are polynomially 𝜒-bounded 2018 December 1, 2018: 2018 SCMS Workshop on Extremal and Structural Graph Theory , Shanghai Center for Mathematical Sciences, Fudan University, Shanghai, ChinaClasses of graphs with no long cycle as a vertex-minor are polynomially 𝜒-bounded November 24, 2018: 2018 Pohang Mathematics Workshop , The Ocean Resort, YeosuVertex-minors and pivot-minors of graphs November 3, 2018: KSIAM 2018 Annual Meeting , Ramada Hotel, JejuClasses of graphs with no long cycle as a vertex-minor are polynomially 𝜒-bounded August 20-23, 2018: KIAS-AORC Joint Workshop (21st KIAS Combinatorics Workshop) , Elysian Gangchon, ChuncheonIntroduction to Graph Theory (Lecture series) August 6, 2018: 2018 IBS Symposium on Combinatorics , Chung-And University, SeoulSurvey on vertex-minors and pivot-minors of graphs June 5, 2018: Mini-symposium “Graph Structure Theory”, SIAM Conference on Discrete Mathematics , Denver, CO, USAScattered classes of graphs April 19, 2018: Princeton Discrete Math Seminar, Princeton University, Princeton, NJ, USAFinding branch-decompositions of matroids, hypergraphs, and more March 24, 2018: Gyeongsangbuk-do Office of Education Science Gifted Education Center , Pohang잘 칠하기 — 4색 정리, 그래프 이론, 조합적 최적화 January 5, 2018: 2018 International Workshop on Graph Theory , Ewha Womans University, SeoulProperties of intersecting families of ordered sets: revisited 2017 December 18, 2017: KIAS Combinatorics Workshop , Novotel, BusanFinding branch-decompositions of matroids, hypergraphs, and more December 16, 2017: 2017 Korea-China International Conference on Matrix Theory with Applications , Sungkyunkwan University, SuwonProperties of intersecting families of ordered sets: revisited October 12, 2017: GROW2017: Workshop on Graph Classes, Optimization, and Width Parameters , Fields Institute, Toronto, CanadaChi-boundedness of graph classes excluding wheel vertex-minors August 21, 2017: Geometric and Structural Graph Theory , BIRS, Banff, Canada August 16, 2017: 2017 Combinatorics Workshop , Sungkyunkwan University, SuwonChi-boundedness of graph classes excluding wheel vertex-minors June 2, 2017: KIAS Combinatorics Workshop , KIAS, Seoul April 29, 2017: 2017 KMS Spring Meeting , Chosun University, Gwangju.Unavoidable induced subgraphs in large graphs with no homogeneous sets 2016 November 11, 2016: KSIAM 2016 Annual Conference , Seogwipo KAL Hotel, JejuDefective coloring of graphs with excluded subgraphs October 28, 2016: AORC Group 1 Colloquium , Department of Mathematics, Sungkyunkwan University, SuwonRank-width: Algorithmic and Structural Results September 26, 2016: The Southern Italian Workshop on Algorithms and Graphs , ItalyDefective coloring of graphs with excluded subgraphs June 16, 2016: Workshop on Probabilistic and Extremal Combinatorics Downunder , Monash University, Melbourne, Australia.Variants of Hadwiger’s conjecture April 7, 2016: Colloquium, Department of Mathematics, Yonsei University, Seoul.4색정리를 포함하는 Hadwiger의 추측의 변형에 관하여 March 24, 2016: Colloquium, Department of Mathematics, Ewha Womans University, Seoul.4색정리를 포함하는 Hadwiger의 추측의 변형에 관하여 February 19, 2016: 2016 International Workshop on Graph Theory and Combinatorics , Ewha Womans University, Seoul.Variants of Hadwiger’s conjecture January 19, 2016: “Distributed algorithms and graphs” Seminar , Laboratoire d’Informatique Algorithmique: Fondements et Applications (LIAFA), Université Paris Diderot, Paris, France.Variants of Hadwiger’s conjecture 2015 December 15, 2015: Séminaires , Laboratoire d’Informatique, de Modélisation et d’Optimisation des Systèmes, ISIMA (Institut Supérieur d’Informatique, de Modélisation et de leurs Applications), Université Blaise Pascal, Aubiere, France.Variants of Hadwiger’s conjecture December 7, 2015: Graph Theory in the Andes , Los Andes, Chile.Improper coloring and the odd Hadwiger’s conjecture November 1, 2015: 2015 International Workshop on Mathematical Sciences in Dalian , Dalian University of Technology, Dalian, ChinaConstructive algorithm for path-width of matroids October 27, 2015: Colloquium, Department of Mathematics, Choongnam National University, Daejeon.4색정리를 포함하는 Hadwiger의 추측의 변형에 관하여 October 13, 2015: GROW 2015 :the 7th workshop on Graph Classes, Optimization, and Width Parameters (October 11-15) , Aussois, France.Constructive algorithm for path-width of matroids August 26, 2015: 1st Korean Workshop on Graph Theory , KAIST.Counting cliques in graphs with a forbidden subdivision August 10, 2015: Extremal Combinatorics, Probabilistic Combinatorics, and their applications, The 8th International Congress on Industrial and Applied Mathematics (ICIAM 2015) , Beijing, China.Counting cliques in graphs with forbidden subdivision July 13, 2015: 2015 Combinatorics Workshop , NIMS, Daejeon.Strongly even-cycle decomposable graphs June 17, 2015: Algorithmic Graph Theory on the Adriatic Coast (16-19 June 2015) , Faculty of Mathematics, Natural Sciences and Information Technologies, University of Primorska, Koper, Slovenia.Constructive algorithm for rank-width of graphs and path-width/branch-width of matroids May 14, 2015: Colloquium, Department of Mathematical Sciences , Seoul National University, Seoul.4색정리를 포함하는 Hadwiger의 추측의 변형에 관하여 March 13, 2015: 7th KIAS Combinatorics Workshop , KIAS, Seoul.Partitioning H-minor-free graphs into three subgraphs with no large components January 29, February 5, 12, 2015:KAIST 명강 4기 , Seoul.잘 짝지우기 (January 29) 잘 칠하기 (February 5) 잘 다니기 (February 12) January 19, 2015: International Workshop on Graph Decomposition , CIRM, Luminy, France.Constructive algorithm for path-width and branch-width of matroids and rank-width of graphs 2014 November 27, 2014: Colloquium, Department of Mathematics, Duksung Women’s University , Seoul.From the Four Color Theorem to Hadwiger’s Conjecture November 14, 2014: Colloquium, Department of Mathematics, Korea University , Seoul.Ramsey-type theorem for graphs without splits July 21, 2014: 2014 International Workshop on Structure in Graphs and Matroids , Princeton University, Princeton, NJ, USA.Constructive algorithm for path-width and branch-width of matroids July 5, 2014: 수학골든벨 KAIST 프로그램, KAIST, Daejeon.Road to become a mathematician (수학자의 길에 관한 이야기) July 5, 2014: Institute of Science Education for the Gifted (과학영재교육원), Choongnam National University , Daejeon. June 27, 2014: KMRS Seminar, Department of Mathematical Sciences, KAIST, Daejeon.An algorithm for path-width and branch-width of matroids June 16, 2014: Minisymposium “Graph Structure – Part I of II”, SIAM Conference on Discrete Mathematics, Minneapolis, MN, USA.Unavoidable vertex-minors in large prime graphs April 18, 2014: Colloquium, Department of Mathematics, POSTECH, Pohang.Ramsey-type theorem for graphs without splits March 13, 2014: Colloquium, Department of Mathematics, Sogang University, Seoul.Ramsey-type theorem for graphs without splits March 8, 2014: 3rd KIAS Combinatorics Workshop , KIAS, Seoul.Unifying duality theorems for width parameters January 28, 2014: Working Group Seminar , University of Hamburg, Hamburg, Germany (with Reinhard Diestel ).Unifying duality theorems for width parameters in finite graphs January 14, 2014: Working Group Seminar , University of Hamburg, Hamburg, Germany.Hyperbolic surface subgroups of one-ended doubles of free groups 2013 December 16, 2013: Monday Lecture, Institut für Mathematik, Technische Universität Berlin , Berlin, Germany.Vertex-minors and split decompositions of graphs November 14, 2013: Institutskolloquium , Institut für Informatik , University of Rostock, Rostock, Germany. October 1, 2013: DIMAP Seminar , Center for Discrete Mathematics and its Applications, University of Warwick, UK. July 1, 2013: Special Session on Combinatorics and Graph Theory, the Asian Mathematical Conference AMC2013 (June 30-July 4) , Busan, Korea.Excluded vertex-minors for graphs of linear rank-width at most k June 24, 2013: Special Session on Combinatorics and Discrete Mathematics , 2nd Pacific Rim Mathematical Association Congress (June 24-28) , Shanghai, China. June 5, 2013: Working Group Seminar , University of Hamburg, Hamburg, Germany (with O-joung Kwon ).Unavoidable vertex-minors for large prime graphs April 19, 2013: Research Seminar , University of Hamburg, Hamburg, Germany.Width-parameters and tree-decompositions of graphs and matroids April 14, 2013: Vortrag im Seminar Diskrete Mathematik und Optimierung, Institut für Optimierung und Diskrete Mathematik , Technische Universität Graz, Graz, Austria.Even cycle decompositions of graphs with no odd K4 minor March 20, 2013: Dagstuhl workshop “Bidimensional Structures: Algorithms, Combinatorics and Logic” (March 17-22) , Schloss Dagstuhl, Dagstuhl, Germany.Forbidden vertex-minors for graphs of linear rank-width at most k February 21, 2013: Working Group Seminar , University of Hamburg, Hamburg, GermanyVertex-minors and pivot-minors, concepts and overview January 30, 2013: グラフ・ネットワークにおける理論と最適化グループセミナー (Graph Network Theory and Optimization Group Seminar) , National Institute of Informatics, Tokyo, Japan.Well-quasi-ordering conjecture for pivot-minors January 22, 2013: KAIST 글로벌 사이언스 리더 캠프 (2012학년도 부산광역시 과학영재교육원 겨울집중수업), KAIST 영재교육센터. 2012 December 7, 2012: KAIST 일반전형 창의인성면접자 합격생 워크샵 및 멘토링 프로그램, KAIST. November 15, 2012: 자연과학강좌, Chungbuk National University , Cheongju.4색 정리 이야기 (Story on Four Color Theorem) October 27, 2012: 2012 International Conference on Graph Theory, Combinatorics and Applications (October 27-30), Zhejiang Normal University , Jinhua, China.Even cycle decomposition of graphs with no odd K4 minor October 18, 2012: Discrete Convexity and Optimization (October 15-18), RIMS Workshop , Kyoto, Japan.Even cycle decomposition of graphs with no odd K4 minor October 5, 2012: Invited talk, 2012 KMS Fall Meeting (October 5-6) , Daejeon.Even cycle decomposition of graphs with no odd K4 minor August 20, 2012: Invited session on structural graph theory and methods , 21st International Symposium on Mathematical Programming (August 19-24), Berlin, Germany. July 24, 2012: 젊은 지성과의 만남, 영스타클럽(Korean Science and Technology Young Stars Club) 포럼 (July 24-25, 2012), KAIST August 3, 2012: Third workshop on graphs and matroids (July 29-August 4), Maastricht, The NetherlandsEven cycle decomposition of graphs with no odd K4 minor June 19, 2012: SIAM Conference on Discrete Mathematics (June 18-21), Dalhousie University, Halifax, Nova Scotia, Canada.Rank-Width and Well-Quasi-Ordering of Skew-Symmetric Or Symmetric Matrices June 1-7, 2012: Mini-school on Widths-Minors-Matroids , Department of Informatics, University of Bergen, Bergen, Norway.June 1: Relation of rank-width with clique-width June 4: Rank-width and vertex-minors; their relations to binary matroid minors June 5: Branch-width of symmetric submodular functions and their recognition algorithms June 6: Excluded pivot-minors for rank-width June 7: Isotropic systems and vertex-minors; how to write C2MS logic formula for testing vertex-minors May 9, 2012: Graph Theory @ Georgia Tech, Conference Honoring the 50th Birthday of Robin Thomas (May 7-11), Georgia Tech, Atlanta, USA.Graphs of small rank-width is a pivot-minor of graphs of small tree-width April 12, 2012: Colloquium, Department of Mathematics, Chonbuk National University, Jeonju, Korea.Survey on vertex-minors and pivot-minors 2011 December 14, 2011: The Second Bertinoro Workshop on Algorithms and Graphs , Bertinoro, Italy.Rank-width and well-quasi-ordering of skew-symmetric or symmetric matrices November 8, 2011: Robin Thomas Fest , Charles University, Prague, Czech.Rank-width and well-quasi-ordering of skew-symmetric or symmetric matrices October 18, 2011: Seminar, Department of Computer Science and Engineering, Seoul National University, Seoul.Vertex-minors, Monadic Second-Order Logic, and a Conjecture by Seese September 2, 2011: European Conference on Combinatorics, Graph Theory, and Applications (Eurocomb), Budapest, Hungary.Rank-width and well-quasi-ordering of skew-symmetric or symmetric matrices August 18, 2011: Combinatorics Workshop2011 조합론 학술대회 , Kangwon National University, Chuncheon.Computing Rank-width Exactly August 4, 2011: 2011 초등 수학과학 영재교사 직무연수, 충남대학교 과학영재교육원, Choongnam National University, Daejeon.4색 정리 이야기 (Story on Four Color Theorem) June 28, 2011: Noon Lecture, Department of Applied Mathematics (KAM) , Charles University, Prague.Vertex-minors and pivot-minors of graphs June 10, 2011: Special Department Seminar, Department of Mathematics, Yeungnam University, Kyoungsan.A survey on vertex-minors and pivot-minors April 29, 2011: Special Session on Graph Theory , Korean Mathematical Society Spring Meeting, Korea University, Seoul.Rank-width and Well-quasi-ordering of Skew-symmetric or Symmetric Matrices April 19, 2011: 자연과학대학 대중강연 (Public Lecture of College of Natural Science), KAIST.4색정리 이야기 (Story on Four Color Theorem) April 11, 2011: 유학준비생을 위한 강연, KAIST. February 16, 2011: Graph Algorithm and Combinatorial Optimization , NII Shonan Meeting, Shonan Village Center, Japan.Rank-width and Well-quasi-ordering of Skew-symmetric or Symmetric Matrices 2010 December 3, 2010: Public Lecture, 금요일에 과학터치 , 대전교육과학연구원, Daejeon.Mathematics of Matchings짝지우기의 수학 November 17, 2010: Kyoto Prize Satellite Workshop in Tokyo in honor of Professor László Lovász , Tokyo Institute of Technology, Tokyo.Hyperbolic surface subgroups of doubles of free groups September 9, 2010: New trends on structural graph theory , Banff Workshop, Banff, Canada.Hyperbolic surface subgroups of doubles of free groups August 25, 2010: 대구과학고 아카데미 강연, Daegu Science High School, Daegu. August 23, 2010: Robot Vision 연구회 세미나, Samsung 생산기술연구소, Suwon.그래프이론 소개 (Introduction to Graph Theory) August 20, 2010: Invited Talk, 2010 Combinatorics Workshop , Yeungnam University, GyeongsanHyperbolic surface subgroups of one-ended doubles of free groups August 13, 2010: Invited Lecture, KAIST 수학문제연구회 영재캠프, KAIST, DaejeonMathematics of Matchings짝지우기의 수학 June 21, 2010: 40th Algebraic Combinatorics Seminar , Kyungpook National University, Daegu.Well-quasi-ordering conjecture for pivot-minors June 16, 2010: Minisymposium on Structural Graph Theory , SIAM Conference on Discrete Mathematics , Austin, Texas, USA.Perfect matchings in claw-free cubic graphs April 24, 2010: Lecture for KMS Excellent Paper Award, KMS Spring Meeting, Korean Mathematical Society, Choongnam National University, Daejeon.Vertex-minors, monadic second-order logic, and a conjecture by Seese April 24, 2010, Invited Public Lecture, Korean Women in Mathematical Society한국여성수리과학회 , Choongnam National University, Daejeon.Mathematics of Matchings짝지우기의 수학 April 17, 2010: The 3rd Annual Meeting of the Asian Association for Algorithms and Computation (AAAC2010) , POSTECH, Pohang.Computing rank-width exactly March 24, 2010: Invited Seminar, National Institute of Mathematical Sciences (NIMS) , Daejeon.Rank-width of Random Graphs February 15-19, 2010: One-Week Workshop on New Development of Discrete Algorithms , Tokyo Institute of Technology, Tokyo, Japan.(2/15) Testing branch-width at most k for fixed k or non-fixed k February 10, 2010: The First Wednesday Multidisciplinary Forum첫수융합포럼 , KAIST. January 11-13, 2010: Winter School on Algorithms and Combinatorics , Jochiwon, Korea.(1/12) Parameterized Complexity (1/13) Width Parameters of Graphs 2009 December 19, 2009: Special session on combinatorial matrix theory, Joint Meeting of the Korean Mathematical Society and the American Mathematical Society , Ewha Womans University, Seoul.Perfect matchings in claw-free cubic graphs December 17, 2009: Parameterized complexity and approximation algorithms , Dagstuhl, Germany. December 10, 2009: Bertinoro Workshop on Graphs and Algorithms , Bertinoro, Italy.Perfect matchings in claw-free cubic graphs October 20, 2009: Informatics Colloquium, Faculty of Informatics, Masaryk University , Brno, Czech Republic.Maximum number of complete subgraphs in a certain graph October 16, 2009: Fourth workshop on Graph Classes, Optimization, and Width Parameters (GROW 2009) , Bergen, Norway.Computing rank-width exactly September 17, 2009: Colloquium, Department of Mathematics, Sungkyunkwan University , Suwon, South Korea.Vertex-minors and pivot-minors of graphs June 8, 2009: 첨단과학세미나, Korea Science Academy한국과학영재학교 , Pusan, South Korea.Planar graphs and circle graphs June 4, 2009: 2009 ASARC Workshop, Muju resort, South Korea.A survey on vertex-minors and pivot-minors May 9, 2009: DIMACS Workshop on Graph Colouring and Structure , Princeton University, Princeton, New Jersey, USA. April 25, 2009: 2009 KMS Spring Meeting , Department of Mathematis, Ajou University , Suwon, South Korea.Maximum number of complete subgraphs in a certain graph February 4, 2009: KAIST Combinatorics Seminar , Department of Mathematical Sciences, KAIST , Daejeon, South Korea.Maximum number of complete subgraphs in a certain graph January 30, 2009: 2009 ASARC Workshop at Daecheon, Daecheon, South Korea.Maximum number of complete subgraphs in a certain graph January 9, 2009: Seminar, Department of informatics, University of Bergen , Bergen, Norway.Maximum number of complete subgraphs in a certain graph January 8, 2009: Department Seminar, Department of informatics, University of Bergen , Bergen, Norway.Introduction to Rank-width 2008 December 22, 2008: Kyoto RIMS Winter School on Graphs and Algorithms , RIMS, Kyoto University , Kyoto, Japan.Survey on Rank-width and Clique-width November 5, 2008: Math Club, Department of Mathematics, POSTECHSeese’s conjecture on the decidability of the monadic second-order theory November 1, 2008: 수학문제연구회 20주년 기념행사 (20th year anniversary event of KAIST Mathematical Problem Solving Group), KAIST Mathematical Problem Solving Group, KAIST.그래프 집합 위에서의 단항이차논리식의 결정가능성에 관한 Seese의 추론 October 16, 2008: Colloquium, Department of Mathematics, Ajou University , Suwon, Korea.Seese’s conjecture on the decidability of the monadic second-order theory September 30, 2008: Graph minors , Banff International Research Station, Banff, Canada.Tree-width and rank-width of H-minor-free graphs August 7, 2008: 2008 Combinatorics Workshop , Sungkyungkwan University, Suwon, Korea.Finding branch-decompositions and rank-decompositions. July 20, 2008: The Netherlands Workshop on Graphs and Matroids , Sittard, the Netherlands. June 24, 2008: Fudan-KAIST Joint Workshop on Applied Mathematics, School of Mathematical Sciences, Fudan University , Shanghai, China.Chain theorems for 4-prime graphs June 16, 2008: SIAM Conference on Discrete Mathematics , University of Vermont, Burlington, Vermont, USA.Chain theorems for 4-prime graphs June 12, 2008: Kyoto RIMS Workshop on Combinatorial Optimization and Discrete Algorithms , Research Institute for Mathematical Sciences (RIMS) , Kyoto University, Kyoto, Japan. April 7, 2008: Workshop on Graph Decomposition: Theoretical, Algorithmic and Logical Aspects , CIRM , Luminy, France. April 3, 2008: Combinatorics Seminar , LaBRI , Bordeaux, France.Line graphs of large rank-width March 28, 2008: Special session on Structural graph theory , AMS sectional meeting , Baton Rouge, Lousiana, USA.Chain theorems for 4-prime graphs February 21, 2008: Undergraduate Colloquium학부생 콜로퀴엄 , Department of Mathematical Sciences, KAIST. February 1, 2008: 4th Korea-Japan Workshop on Algebra and Combinatorics , POSTECH, Pohang, Korea.Well-quasi-ordering of skew-symmetric matrices of bounded rank-width 2007 December 3, 2007: Colloquium , Department of Computational and Applied Mathematics, Rice University, Houston, Texas, USA.Introduction to Rank-wdth November 27, 2007: Combinatorial Optimization Seminar , University of Waterloo, Waterloo, Ontario, Canada.Finding Branch-decompositions and Rank-decompositions November 16, 2007: Joint Combinatorics – Theory Seminar, University of Toronto, Toronto, Canada.Introduction to Rank-width October 19, 2007: The Third Workshop on Graph Classes, Optimization, and Width Parameters, Eugene, Oregon, USA. August 6-8, 2007: 2007 Combinatorics Workshop , KAIST, Daejeon, Korea.Circle graphs obstructions under pivoting (August 6) Excluding a bipartite circle graph from line graphs (August 7) Rank-width and well-quasi-ordering (August 8 ) July 25, 2007: Structure Theory and FPT Algorithms for Graphs, Digraphs and Hypergraphs , Dagstuhl workshop 07281, Germany. May 28, 2007: 1st Canadian Discrete and Algorithmic Mathematics Conference (CanaDAM 2007) , Banff, Alberta, Canada.Circle graph obstructions under pivoting May 10, 2007: Colloquium, Department of Mathematics, Yonsei University , Seoul, Korea.Survey on rank-width and clique-width May 8, 2007: Special Lecture, Department of Mathematics, POSTECH , Pohang, Korea.Survey on rank-width and clique-width May 2, 2007: Colloquium , Department of Mathematical Sciences, KAIST , Daejeon, Korea.Survey on rank-width and clique-width March 28, 2007: Oberwolfach Workshop Graph Theory , Oberwolfach, Germany.Excluded pivot-minor characterization of circle graphs January 23, 2007: Combinatorial Optimization Seminar, University of Waterloo, Canada.Circle graph obstructions under pivoting 2006 November 16, 2006: Graph Theory Seminar, Georgia Institute of Technology, USA.Circle graph obstructions under pivoting August 4, 2006: Tutte Seminar , University of Waterloo, Canada.Survey on rank-width and clique-width July 21, 2006: Horizon of Combinatorics , Lake Balaton, Hungary.Excluding a bipartite circle graph from line graphs July 11, 2006: Sixth Czech-Slovak International Symposium on Combinatorics, Graph Theory, Algorithms and Applications , Prague, Czech Republic.Excluding a bipartite circle graph from line graphs June 25, 2006: SIAM Conference on Discrete Mathematics , Victoria, British Columbia, Canada.Towards a Grid Theorem for Rank-width and Clique-width May 20, 2006: The XXVIIIth Ohio State-Denison Mathematics Conference , Columbus, OH, USA.Towards a Grid Theorem for Rank-width and Clique-width April 27, 2006: Graph Theory Seminar, Georgia Institute of Technology, USA.Towards a Grid Theorem for Rank-width and Clique-width February 9, 2006: Graph Theory Seminar, Georgia Institute of Technology, USA. January 23, 2006: ACM/SIAM Conference on Discrete Algorithms (SODA) , Miami, FL, USA. 2005 December 27, 2005: Combinatorics Seminar, Department of Mathematics , KAIST , Daejeon, Korea. November 24, 2005: Combinatorics and Optimization Seminar , University of Waterloo, Waterloo, Canada. October 18, 2005: Workshop on Graph Classes, Width Parameters and Optimization , Prague, Czech. October 13, 2005: Graph Theory Seminar, Georgia Institute of Technology, USA.Graphs of Bounded Rank-width II October 12, 2005: Combinatorics Seminar , Georgia Institute of Technology, USA.Rank-width and Well-quasi-ordering of Skew-symmetric Matrices October 6, 2005: Graph Theory Seminar, Georgia Institute of Technology, USA.Graphs of Bounded Rank-width September 24, 2005: The 41st Midwest Graph Theory Conference , Middle Tennessee State University, Murfreesboro, TN, USA.Approximating Rank-width and Clique-width Quickly September 13, 2005: 7th International Colloquium on Graph Theory (ICGT ’05) , Hyères, France.Rank-width and well-quasi-ordering of skew-symmetric matrices July 26, 2005: Exact Algorithms and Fixed-Parameter Tractability , Dagstuhl workshop, Germany. July 3, 2005: Princeton-Oxford Workshop, Oxford, UK. June 23, 2005: 31st International Workshop on Graph-Theoretic Concepts in Computer Science , Metz, France. June 20, 2005: Seminar on graphs and logic, University of Bordeaux 1, Bordeaux, France.Graphs of Bounded Rank-width June 16, 2005: Séminaire de Combinatoire Algébrique et Géométrique , Combinatoire et Optimisation , Université Pierre et Marie Curie (Paris 6), Paris, France January 19, 2005: Oberwolfach Workshop “Graph Theory “ , Oberwolfach , Germany 2004 December 17, 2004: Workshop “Graph and Hypergraph Decompositions – Methods and Applications in Computer Science November 19, 2004: PACM Graduate Student Seminar , Princeton UniversityRank-width and Well-quasi-ordering November 15, 2004: Discrete Mathematics and Optimization Seminar , McGill University , Montreal, Quebec, Canada October 29, 2004: Graph Theory Seminar, Georgia Institute of Technology October 1-2, 2004: two talks were given at the Satellite Workshop Logic, Graph Transformations, Finite and Infinite Structures 2nd International Conference on Graph Transformations (IGCT) in Rome, Italy. Titles are May 25, 2004: Robust and Approximative Algorithms on Particular Graph Classes March 10, 2004: Princeton Discrete Mathematics Seminar From binary matroids to graphs February 27, 2004: PACM Graduate Student Seminar From binary matroids to graphs 2003 