** 2018 **

Oct. 8-12, 2018, Invited speaker, Discretization in Geometry and Dynamics, Döllnsee-Schorfheide, North of Berlin, Germany.

** 2017 **

Oct. 9-13, Geometric analysis, organized by Centre Henri Lebesgue, University of Brest and University of Nantes, at Station Biologique de Roscoff, France

Oct. 7, Workshop on Topology: Identifying Order in Complex Systems. University of Pennsylvania, Pennsylvania.

Sept. 14-15, ATD workshop, American University, DC.

July 10-19, Computational Topology and Geometry, FoCM'17, Barcelona, Spain.

June 12-16, Geometry and Shape Analysis in Biological Sciences, National University of Singapore, Singapore.

March 13-17, Curvatures of graphs, simplicial complexes and metric spaces, Sanya International Mathematics Forum, Sanya, China.

** 2016 **

Dec. 12-17, 2016, Quantum invariants and low-dimensional topology, The international Mathematical Research Institute MATRIX, Victoria, Australia

Sept 24-25, Eastern AMS Sectional meeting, Bowdoin College in Brunswick, Maine.

August 15-19, 2016, "Program on Geometry, Topology and Dynamics of Moduli Spaces", National University of Singapore, Singapore.

August 13-14, 2016, “Workshop on Discrete Analysis”, Shanghai Center of Mathematical Sciences, Fudan University, Shanghai, China.

July 24-30, 2016, "On the Grothendieck-Teichmüller theory and mapping class groups", Chern Institute of Mathematics, Tianjin, China

June 27-July 1, 2016, Geometric Analysis, Metric Geometry and Topology at Institut Fourier, Grenoble, France.

June 20-June 24, 2016, give a lecture series titled "An introduction to discrete conformal geometry of polyhedral surfaces" in the summer school Geometric analysis, Metric geometry and Topology, Institut Fourier, Grenoble, France. Videos: Lecture 1 , Lecture 2 , Lecture 3 , Lecture 4 , Lecture 5

May 3-19, 2016, University of Sydney, Australia

March 19-20, AMS regional meeting at Stony Brook

Jan. 11-16, “Teichmüller theory and low-dimensional topology” , Sanya International Mathematics Forum, Sanya, China

** 2015 **

Oct. 5-9, 2015, "Geometric Structures on 3-Manifolds", IAS, Princeton, NJ. My talk Rigidity of the hexagonal triangulation of the plane and its applications.

August 10-14, 2015, organizer, Invariants in low dimensional geometry, Gazi University, Ankara, Turkey.

August 2-8, 2015, visiting and giving a talk at CENTRE FOR QUANTUM GEOMETRY OF MODULI SPACES, Aarhus, Denmark.

July 6-10, 2015, Scientific committee, Classical and quantum hyperbolic geometry and topology, Université Paris-Sud (Orsay), France.

April 21-22, 2015, Identities in New York , CUNY graduate center. New York.

April 16, 2015, topology seminar, Princeton Univ.

April 14, 2015, colloquium speaker, Purdue University

March 26, 2015, topology seminar, Stony Brook

March 1-7, 2015, Oberwolfach workshop on discrete differential geometry, Germany

Jan. 15, 2015, topology seminar, Caltech

Jan. 13, 2015, Microft Station Q seminar, Santa Barbara

** 2014 **

Dec. 15-19, Sanya International Mathematics Forum, Sanya, China

August 22-26, Knots and Low Dimensional Manifolds , Busan, Korea.

August 4-8, geometry and physics of Higgs bundles, National University of Singapore, Singapore

July 27-Aug. 1, Mathematical Foundation of Modern Data Sciences, Dalian, China

June 30-July 5, co-organizer, Geometry, Quantum Topology and Asymptotics, University of Geneva, Switzerland

Mar 15-22, University of Sydney and University of Melbourn, Australia

Mar 10-12, ATD workshop, Boulder, Colorado.

Feb. 9-15, Oberwolfach workshop on Teichmuller theory and mapping class groups, Germany

** 2013 **

Nov. 5-8, "Geometry of Moduli Spaces of Low Dimensional Manifolds", RIMS, Kyoto University, Japan

Oct. 23, colloquium talk, Lehigh University

Oct. 12, special session of AMS meeting, Philadelphia

Sept. 11-15, BMS/SFB Summer School: Discrete Differential Geometry, Berlin, Germany

August 12-16, Geometric Topology in New York, Columbia University

July 14-19, ICCM 2013, Taiwan

May 8-June 14, visiting and giving a lecture series at Mathematical Sciences Center (MSC) , Tsinghua University, Beijing China

April 26-28, Workshop on Minimal Surfaces, 3-Manifold Topology and Related Topics, MIT

April 18, colloquium talk, SUNY, Stony Brook

April 7-12, Banff workshop, Canada

March 16-24, University of Pisa, Italy

** 2012 **

August 3-6, invited speaker, "International conference on complex geometry, singularities and related fields", Beijing, China.

July 21-29, invited speaker, "International conference on group actions and applications in geometry, topology and analysis", Kunming, China.

July 19-21, invited speaker, The 3-D Geometry/Imaging Conference, Kunming, China.

July 8-14, invited speaker, Oberwolfach workshop on Discrete Differential Geometry, Germany

June 25-29, invited speaker, Mapping Class Groups and Quantum Topology, IRMA, University of Strassboug, France

April 29-May 5, invited speaker, Oberwolfach workshop on Triangulations, Germany

March 26-April 25, invited lecturer, Mathematical Science Center, Tsinghua University, Beijing, China

April 13, colloquium talk, School of Math, Peking University, Beijing China

March 22, Topology seminar, SUNY Stony Brook

** 2011 **

March 13-14, invited speaker, geometry and topology workshop, Princeton University.

May 25-26, invited speaker, "Knots and Applications", Centro di Ricerca Matematica Ennio De Giorgi, Pisa, Italy. My talk "a dilogarithm identity on moduli spaces of curves".

June 14-July 16, a series of 20-hour-lectures on Riemann surfaces and Teichmuller theory, Mathematical Science Center, Tsinghua University, Beijing, China,

July 8, seminar speaker at the dept of Math, The Capital Normal University, Beijing, China.

July 14, seminar speaker at the Mathematics Institute of the Chinese Acadmey of Science, Beijing, China.

July 18-22, invited speaker, "Geometry & Topology Down Under" (Hyamfest), The University of Melbourne, Australia, My talk "variational principles and rigidity on triangulated surfaces".

Oct. 6, Topology seminar at Princeton University

Oct. 21, Topolog seminar at Columbia University

Nov. 15, Topology seminar at Temple University

Dec. 13, Geometry seminar at UC San Diego

** 2010 **

Jan. 8, topology seminar, Caltech, Los Angeles

Jan. 12, topology seminar, UC Santa Barbara

April 15, Topology seminar, City University of New York, Graudate Center

May 17-21, invited speaker, Barrett Memorial Lectures, University of Tennessee, Knoxville my lecture.

June 4-6, speaker and co-organizer, "Topology and geometry in dimension three"- celebrating Jaco's 70-th birthday, University of Oklahoma, Stillwater

July 7-16, invited speaker, workshop on geometric topology, Changchun, China.

July 16, invited lecture at the Center of Mathematical Science, Qinghua University, Beijing

July 19, invited lecture at the Beijing International Center for Mathematical Research, Beijing

July 20, invited lecture at the capital Normal University, Beijing

July 19-30, invited speaker, Topology, Geometry and Dynamics of character varieties, National University of Singapore

August 11-12, invited speaker, Sullivan Seminar, State University of New York, NY

Sept. 2-4, invited speaker, Encounters between mathematicians and theoretical physicists, University of Strassboug, France

Dec. 17-20, invited speaker, International Congress of Chinese Mathematicians, Qinghua University, China.

** 2009 **

Jan. 5-6, invited speaker, AMS meeting at Washington DC.

Jan. 10-17, invited speaker, Oberwolfach workshop on discrete differential geometry

Feb. 11-15, colloquium talk at Arizona State

April 14, seminar talk at University of Maryland

June 15-19, invited speaker, "Interactions Between Hyperbolic Geometry, Quantum Topology and Number Theory ", Columbia University, New York

July 7-14, invited speaker, "Workshop on low-dimensional manifolds", East China Normal University, Shanghai, China

** 2008 **

March 13, 2008, invited speaker, topology seminar, Princeton University

April 25, 2008, colloquium speaker, Okalahoma State University.

May 13, 2008, invited speaker, bay area topology seminar, Univ. of California, Davis.

June 4, 2008, invited speaker, Mini-Symposia, IEEE International Conference on Shape Modeling and Applications , State University of New York, Stony Brook.

June 16-28, 2008, invited speaker, International workshop and conference on surface mapping class groups and related topics. Meghalaya, India.

June 30-July 11, 2008, Invited speaker, Transformation groups and orbifolds. Hangzhou, China

July 14-20, 2008, Invited speaker, Geometry of Teichmuller spaces and moduli spaces of curves. Hangzhou, China.

Sept. 11-13, 2008, invited speaker, Ricci flow in mathematics and physics , University of Strasbourg, France. my talk

Jan. 8, 2007, AMS special session invited speaker. My talk " the cosine law and volume" . New Orleans, LA.

March. 15, 2007, colloquium speaker, Boston College, "rigidity of polyhedral surfaces" .

April 12-14, 2007, invited speaker, ASPECTS OF TEICHMUELLER THEORY, University of Michigan.

April 28-29, 2007, invited speaker, "Pacific Northwest Geometry Seminar" Univ. of Utah.

May 20-26, 2007, invited speaker, "BRAIDS AND THEIR RAMIFICATIONS" Cortona, Italy.

May 30-June 3, 2007, invited speaker, "A second time around the volume conjecture" Louisiana State University. .

June 18-22, 2007, speaker and co-organizer, "Geometric topology" Beijing, China .

June 25-30, 2007, speaker and co-organizer, Geometric topology and geometric analysis , CMS, Zhejiang University, Hangzhou, China.

July 16-20, 2007, invited speaker, "Discrete Differential Geometry" Berlin, Germany.

July 27-31, 2007, speaker and co-organizer, International Conference on Topology and Physics - In Memory of Xiao-Song Lin, Tianjin, China.

Oct. 20-21, invited speaker, "workshop on geometric evolution equations", UC San Diego.

Dec. 17-22, 2007, invited plenary speaker, "The fourth International Congress of Chinese Mathematicians", Hangzhou, China.

** 2006 **

March 6-10, 2006, invited speaker, Oberwolfach workshop Discrete differential geometry. My talk "some applications of the cosine law" .

March 16-19, 2006, invited speaker (two lectures), Geometric Group Theory on the Gulf Coast.

May 17-21, 2006, invited speaker, Georgia Topology Conference .

Oct. 27-29, 2006, invited speaker, Texas Geometry and Topology Conference . My talk "volume and angle structures on 3-manifolds".