Academic Visits Hong Kong University, Oct. 3--9, 1993. Given talk (1993-10-06): A survey of covering theory. Trento University (Italy), Sept. 24, 1995--Sept. 6, 1996. Given talk (1995-10-24): A sketch of covering theory. > Genova University (Italy), June 4--6, 1996. Given talk (1996-06-05): Simple ideas for famous problems. Pisa University (Italy), July 11--12, 1996. Given talk (1996-07-11): Coverings of the integers and groups. Center for Combinatorics, Nankai University, March 6--August 16, 1999. Hong Kong University of Science and Technology, Feb. 28--April 14, 2000. Chinese University of Hong Kong, April 7, 2000. Given talk (2000-04-07): Various number-theoretic quotients and related congruences. Hong Kong University, April 10, 2000. Given talk (2000-04-10): Recent progress on covers of the integers and their applications. City University of Hong Kong, April 14, 2000. Given talk (2000-04-14): On Hilbert's tenth problem and related topics. Chinese University of Hong Kong, July 23--August 22, 2000. Institute of Mathematics, Academia Sinica (Taiwan), May 1--June 30, 2002. Given talk (2002-05-16): Equalities and inequalities related to covers of $\Bbb Z$ or groups. National Sun Yat-sen Univ. (Taiwan), May 27--29, 2002. Given talk (2002-05-28): On zero-sum problems. National Taiwan Normal Univ. (Taiwan), June 12, 2002. Given talk (2002-06-12): On the sum $\sum_{k\equiv r (mod m)}\binom{n}{k}$ and related results. National Taiwan Univ., June 24, 2002. Given talk (2002-06-24): On the structure of periodic arithmetical maps. National Taiwan Univ., Nov. 4--12, 2002. Given talk (2002-11-06): On the sum $\sum_{k\equiv r (mod m)}\binom{n}{k}$ and related results. Institute of Mathematics, Academia Sinica (Taiwan), Nov. 11, 2002. Given talk (2002-11-11): Snevily's conjecture on abelian groups and an algebraic method in combinatorics. Kyushu University (Fukuoka, Japan), Nov. 16--22, 2003. Given talk (2003-11-21): How to unify covering systems, restricted sumsets and zero-sum problems. Northwest University (Xi'an, China), Feb. 12--16, 2004. Given talk (2004-02-13): Recent progress on zero-sum problems and Snevily's conjecture. ICTP (International Centre for Theoretical Physics) (Trieste, Italy), May 24--June 12, 2004. Graz University (Graz, Austria), June 13--19, 2004. Given talk (2004-06-14): Covering systems and their connections to zero-sum problems. Vienna University of Technology (Vienna, Austria), June 17, 2004. Given talk (2004-06-17): On disjoint systems of residue classes or cosets of subgroups. Genova University (Genova, Italy), June 20--25, 2004. Given talk (2004-06-23): On the Erd\"os-Heilbronn conjecture and Snevily's conjecture. Firenze Univ. (Florence, Italy), June 26--28, 2004. Given talk (2004-06-28): On various combinatorial sums and related identites. Univ. Roma "Tor Vergata" (Rome, Italy), June 28--30, 2004. Given talk (2004-06-30): Two local-global theorems and a powerful formula. Institut Camille Jordan, Universit\'e Claude Bernard Lyon-I (France), Jan. 11--March 10, 2005. A typical talk (2005-01-13): Identities and congruences for Bernoulli and Euler polynomials. Univ. Saint-Etienne (France), Feb. 1, 2005. Given talk (2005-02-01): Problems and results on covering systems. Univ. Bordeaux I (France), Feb. 16--18, 2005. Given talk (2005-02-17): Some effective results related to covers of Z and zero-sum problems. Univ. California at Irvine (USA), May 13, 2005--May 6, 2006. Given talk (2005-05-25): Problems and results on covering systems. Given talk (2005-11-10): On some conjectures of Erdos-Heilbronn, Lev and Snevily. Given talk (2006-01-19): A survey of zero-sum problems on abelian groups. Univ. Wisconsin at Madison (USA), April 3--8, 2006. Given talk (2006-04-04): Some curious results on Bernoulli and Euler polynomials Given talk (2006-04-06): Recent progress on congruences involving binomial coefficients. Univ. Illinois at Urbana-Champaign (USA), April 12--14, 2006. Given talk (2006-04-13): Covering systems and periodic arithmetical functions. Massachusetts Institute of Technology (MIT, USA), April 20--22, 2006. Given talk (2006-04-21): Combinatorial aspects of covers of groups by cosets or subgroups. Zhejiang Univ., May 24--28, 2006. Given talk (2006-05-26): Some congruences motivated by algebraic topology. ECNU Workshop on q-Series (East-China Normal Univ., June 21, 2006). Given talk (2006-06-21): Some congruences concerning q-Euler numbers, q-Salie numbers and q-Carlitz numbers. Internat. Workshop on Finite Fields and their Appl. (Chenxing Math. Center, July 3--7, 2006). Given talk (2006-07-07): p-adic orders of some sums involving binomial coefficients. The Fourth China-Japan Conf. on Number Theory (Shandong Univ., Weihai, Aug. 30--Sept. 3, 2006). Given talk (2006-08-30): Curious identities and congruences involving Bernoulli polynomials. Beijing Normal University, Jan. 25, 2007. Given talk (2007-01-25): Problems and results on restricted sumsets. The Institute of Mathematics, Chinese Academy of Sciences (Beijing), Jan. 22--30, 2007. Given talk (2007-01-30): Combinatorial aspects of Szemeredi's theorem. Zhejiang University, April 5--8, 2007. Given talk (2007-04-06): Additive combinatorics and Latin transversals. The Fourth Cross-Strait Conf. on Graph Theory and Combin. (National Taiwan Univ., Taipei, June 24--27, 2007). Given talk (2007-06-24): An additive theorem and restricted sumsets. National Cheng Kung University (Tainan), June 28--29, 2007. Given talk (2007-06-28): Sums of squares and triangular numbers, and Rado numbers for linear equations. The 19th Annual Int. Conf. on Formal Power Series and Algebraic Combin. (Nankai Univ., Tianjin, July 2--6, 2007). Given talk (2007-07-04): An additive theorem related to Latin transversals. The 2007 Annual. Conference of the Chinese Math. Soc. (Beijing, Nov. 1--4, 2007). Invited talk (2007-11-3): Some famous problems and related results in combinatorial number theory. The 4th Int. Congress of the Chinese Mathematicians (Zhejiang Univ., Hangzhou, Dec. 17--22, 2007). Invited talk (2007-12-21): Groups in combinatorial number theory. Tongji Univ., Shanghai, Jan. 18--21, 2007. Given talk (2008-01-18): Various extensions of some basic results in combinatorial number theory. The 6th Shanghai Conference on Combinatorics (Shanghai Jiao Tong Univ., May 24--28, 2008). Plenary talk (2008-05-28): Recent problems and results involving binomial coefficients. Suzhou Univ., Suzhou, June 18--20, 2008. Given talk (2008-06-19): An extremal problem on covers of abelian groups. Nankai Univ., Tianjin, June 23--25, 2008. Given talk (2008-06-24): An extremal problem on covers of abelian groups. The Institute of Mathematics, Chinese Academy of Sciences (Beijing), June 26--30, 2008. Given talk (2007-06-29): Study covers of groups via characters and number theory. The 5th China-Japan Conf. on Number Theory (Kinki Univ., Osaka, Japan), August 27--Sept.1, 2008. Given talk (2008-08-28): On representations of integers involving triangular numbers. Dalian University of Technology, Dalian, Nov. 29--Dec. 3, 2008. Given talk (2008-12-01): An extremal problem on covers of abelian groups. Anhui Normal University, Wuhu, April 22--25, 2009. Given talk (2009-04-23): Some new conjectures involving primes. Ynacheng Normal College, Yancheng, Jiangsu Province, June 14--17, 2009. Given talk (2009-06-16): Some new conjectures involving primes. The Fifth Cross-Strait Conf. on Graph Theory and Combin. (Nankai Univ., Tianjin, July 28--August 1, 2009). Plenary (one-hour) talk (2009-07-31): Probelms and results in additive combinatorics. International Conference on Number Theory and Representations (Shandong Univ., Weihai, August 2--August 7, 2009). Given talk (2009-08-03): Polygonal numbers, primes and ternary quadratic forms. Harish-Chandra Research Institute (Jhusi, Allahabad, India), Jan. 16--Feb. 16, 2010. Six talks were given, here are the last three: (Feb. 4, 2010) On the DKSS technique and the DKSS conjecture. (Feb. 6, 2010) Some sophisticated applications of the Combinatorial Nullstellensatz. (Feb. 8, 2010) Conjectures and results on super congruences. Capital Normal University, Beijing, April 8--10, 2010. Given talk (2010-04-09): Conjectures for super congruences and series for π and other constants. The Second International Workshop on Number Theory, Combinatorics and their Interactions (Luoyang Normal Univ., Luoyang, May 1--3, 2010). Given talk (2010-05-02): Conjectures for super congruences and series for π and other constants. Pacific Rim Conference on Mathematics (Stanford University (USA), June 28--July 2, 2010). Invited talk (2010-07-02): Super congruences involving binomial coefficients and new series for some famous constants. The National Center for Theoretical Sciences (Hsinchu, Taiwan; August 1--August 8, 2010). Given talk (2010-08-02): Problems and results in additive combinatorics. Given talk (2010-08-04): Arithmetic properties of combinatorial quantities. The National Chiao Tung University (Hsinchu, Taiwan; August 5, 2010). Given talk (2010-08-05): On divisibilitity concerning binomial coefficients. The 5th National Conference on Number Theory (Zhaoqing, Guangdong, China; December 25-28, 2010). Given talk (2010-12-27): Correspondence between series and congruences. Shanghai Jiaotong University (March 14-18, 2011). Given talk (2011-03-15): p-adic congruences on combinatorial sums involving binomial coefficients, Given talk (2011-03-17): p-adic congruences on combinatorial sums involving binomial coefficients (II). Zhejiang University (Hangzhou, China; March 24-26, 2011) Given talks (2011-03-25): (1) On weighted extension of the Erdos-Heilbronn conjecture, (2) Dense subsets of the ring of p-adic integers and combinatorial congruences. Hsinghua University (Beijing, China; April 13-14, 2011). Given talk (2011-04-14): Number theory behind series for 1/π. Institute of Mathematics, Chinese Academy of Sciences (Beijing, China; April 15, 2010) Given talk (2011-04-15): On the DKSS conjecture for finite abelian groups. Capital Normal University (Beijing, China; April 15, 2011) Given talk (2011-04-15): Determining x2 mod p2 with 4p=x2+dy2. Workshop in Combinatorics (Peking University, China; May 7-8, 2011) Given talk (2011-05-7): On the DKSS conjecture for finite abelian groups. Chern Institute of Mathematics, Nankai University (Tianjin, China; May 9-15, 2011) Given talk (2011-05-11): Number theory behind series for 1/π. Shandong University (Jinan, China; May 24-26, 2010) Given talk (2010-05-25): On the DKSS conjecture for finite abelian groups. Conference on Number Theory and relatd Fields (Hefei and Huangshan, China; June 7-12, 2011) Given talk (2010-06-08): Conjectures and results on x2 mod p2 with 4p=x2+dy2. The National Chiao Tung University (Hsinchu, Taiwan; June 27-July 2, 2011) Given talk (2010-06-28): Combinatorial congruences via the Zeilberger algorithm. Institute of Mathematics, Academia Sinica (Taiwan), July 3-24, 2011. Given talk (2011-07-06): On arithmetic properties of Bell numbers and Delannoy numbers. Given talk (2011-07-12): Conjectures and results on generalized central trinomial coefficients and Motzkin numbers. Given talk (2011-07-14): Number theory behind series for 1/π. I-Shou University (Kaohsiung, July 18-19, 2011) Given talk (2011-07-19): On the DKSS conjecture for finite abelian groups. The National Center for Theoretical Sciences (Hsinchu, Taiwan; July 19-22, 2011). Given talk (2011-07-20): Some sophisticated congruences involving Fibonacci numbers. East-China Normal University (Shanghai; Oct. 27-29, 2011). Given talk (2011-10-29): Number Theory behind Series for Powers of π. The 2nd National Conference on Combinatorial Number Theory (Guangzhou; Nov. 24-26, 2011). Given talk (2011-11-25): p-adic Congruences Motivated by Series. Jiangsu Normal University (Xuzhou; March 22, 2012). Given talk (2012-03-22): On Functions Taking Only Prime Values. The Morningside Center of Mathematics (Beijing), April 18--22, 2012. Given talk (2012-04-21): On Functions Taking Only Prime Values and Related New Conjectures on Primes. Tsinghua University (Beijing), April 20, 2012. Given talk (2012-04-20): Some Sophisticated Congruences involving Fibonacci Numbers. Workshop on Combinatorics and Graph Theory (Changsha; June 9-11, 2011). Plenary talk (2012-06-10): Generate Primes in a Combinatorial Manner. The 5th National Conference on Combinatorics and Graph Theory (Luoyang; July 16-19, 2011). Plenary talk (2012-07-18): Primes from the Viewpoint of Combinatorics. University of Illinois at Urbana-Champaign, USA (July 23-August 30, 2012). Given talk (2012-08-28): Various New Observations about Primes. City University of New York, USA (August 23-24, 2012). Given talk (2012-08-23): p-adic Congruences Motivated by Series. Dalian University of Technology (Nov. 14-15, 2012). Given talk (2012-11-15): Refinements of Some Famous Problems on Primes. Dalian Maritime University (Nov. 16-17, 2012). Given talk (2012-11-16): Conjectures involving Arithmetical Sequences. Center for Combinatorics, Nankai University (Nov. 30--Dec. 2, 2012). Given talk (2012-12-01): The Riddle of Primes. Tsinghua University (April 12, 2013). Given talk (2013-04-12): Apery Numbers, Franel Numbers and Binary Quadratic Forms. The Morningside Center of Mathematics (Beijing), April 13--15, 2013. Given talk (2013-04-13): Sums of Consecutive Primes and Related Conjectures. Hong Kong University of Science and Technology (April 26--May 5, 2013). Given talk (2013-05-02): Apery Numbers, Franel Numbers and Binary Quadratic Forms. Hong Kong University (May 3, 2013). Given talk (2013-05-03): Some New Representation Problems involving Primes. Guangxi Normal University (June 22-26, 2013). Given talk (2013-06-24): Combinatorial Congruences via Zeilberger's Algorithm and Trees with Prime Vertices. The 5th International Symposium on Graph Theory and Combin. Algorithms (July 12-15, 2012). Given talk (2012-07-14): Combinatorial Congruences via Zeilberger's Algorithm and Trees with Prime Vertices. Zhejiang Univ. (Nov. 14-17, 2013). Given talk (2013-11-15): Determinants, Permutations and Additive Combinatorics. Xiamen Univ. (Dec. 19-22, 2013). Given talk (2013-12-20): Write n = k+m with f(k,m) Prime. Central China Normal Uni. (Jan. 2-5, 2014). Given talk (2014-01-03): Congruences for Franel Numbers. Xiamen Univ. (March 20-23, 2014). Given talk (2014-03-21): Problems on Combinatorial Properties of Primes. Tsinghua Univ. (April 18, 2014). Given talk (2014-04-18): Problems on Combinatorial Properties of Primes. The Morningside Center of Mathematics (Beijing), April 16--20, 2014. Given talk (2014-04-19): Determinants, Permutations and Additive Combinatorics. The 2nd Workshop on Combinatorics and Graph Theory (Changsha, June 1-2), 2014. Given talk (2014-06-02): Determinants, Permutations and Additive Combinatorics. The Workshop on Analytic Number Theory and Cryptology (Beijing, June 14-15), 2014. Given talk (2014-06-14): On Some Arithmetic Functions. Institute of Mathematics, Academia Sinica (Taiwan), July 15--29, 2014. Given talk (2014-07-24): Determinants, Permutations and Additive Combinatorics. Impact of Computation on Number Theory (National Center of Theoretical Science, Hsinchu, July 30--August 3), 2014. Plenary talk (2014-08-03): Determinants, Permutations and Additive Combinatorics. National Center of Theoretical Science, Hsinchu, Taiwan, July 29--August 10, 2014. Given talk (2014-08-06): Towards the Twin Prime Conjecture. Northwest University, Xi'an, October 25--28, 2014. Given talk (2014-10-26): Towards the Twin Prime Conjecture. Given talk (2014-10-27): Supercongruences Motivated by e. Center for Applied Mathematics, Tianjin Univ., Oct. 30--Nov. 2, 2014. Given talk (2014-10-31): Congruences for Franel Numbers. Center for Combinatorics, Nankai Univ., Tianjin, Nov. 3-4, 2014. Given talk (2014-11-03): Towards the Twin Prime Conjecture. Jiangsu Normal Univ., Xuzhou, Jan. 8-11, 2015. Given talk (2015-01-09): On generalized central trinomial coefficients. Capital Normal Univ., Beijing, April 19-21, 2015. Given talk (2015-04-20): On combinatorial properties of primes. Tsinghua Univ., Beijing, May 8, 2015. Given talk (2015-05-08): On universal sums involving polygonal numbers. The Morningside Center of Mathematics (Beijing), May 7--11, 2015. Given talk (2015-05-10): Consecutive primes and Legendre symbols. Dalian University of Technology, May 28--31, 2015. Given talk (2015-05-29): On generalized central trinomial coefficients. Connections in Discrete Mathematics (Simon Fraser Univ., Burnaby, Vancouver, Canada, June 15--19, 2015). Given talk (2015-06-16): On universal sums involving polygonal numbers. The 8th Cross-Strait Conf. on Graph Theory and Comb.(National Sun Yat-sen Univ., Kaohsiung, June 26--July 2, 2015). Given talk (2015-06-28): New divisibility results on certain sums of binomial coefficients. Suzhou University, January 10--12, 2017. Given talk (2017-01-11): The 1-3-5 conjecture and related topics. Jiangsu Normal University, March 11--14, 2017. Given talk (2017-03-13): Restricted sums of three or four squares. Institute of Mathematics, Chinese Academy of Sciences, April 15--18, 2017. Given talk (2017-04-18): Further results on Hilbert's tenth problem. Institute of Mathematics, Chinese Academy of Sciences, April 21--24, 2017. Given talk (2017-04-22): On three-square theorem and its applications. Hebei Normal University, May 13--16, 2017. Given talk (2017-05-15): On Hilbert's tenth problem. The 5th National Conf. on Combin. Number Theory (Huaiyin Normal College, Sept. 15--17, 2017). Given talk (2017-09-16): On Hilbert's tenth problem. Northwest University, October 18--21, 2017. Given talk (2017-10-19): On the DKSS conjecture for finite abelian groups. Given talk (2017-10-20): On the generalized central trinomial coefficients. The 9th Cross-strait Conf. on Graph Theory and Combin., November 2--5, 2017. Plenary talk (2017-11-3): A survey of arithmetic properties of combinatorial quantities. Jiangsu University, November 23--26, 2017. Given talk (2017-11-24): On Snevily's conjecture and related topics. Shandong University, November 30--December 3, 2017. Given talk (2017-12-01): On Snevily's conjecture and related topics. The 3rd Workshop on Combinatorics and Graph Theory at Hunan University (Changsha, December 8--10, 2017). Given talk (2017-12-10): On Snevily's conjecture and related topics. The 4th Sichuan-Chongqing Workshop on Number Theory (Nanchong, December 22--24, 2017). Given talk (2017-12-23): On universal sums x(ax+b)/2+y(cy+d)/2+z(ez+f)/2. Southern Univ. of Sci. and Tech., Janunary 11--13, 2018. Given talk (2018-01-12): On covers of groups by cosets. Shenzhen Univ., January 13, 2018. Given talk (2018-01-13): On universal sums x(ax+b)/2+y(cy+d)/2+z(ez+f)/2. Xia Univ., Jaunary 14--16, 2018. Given talk (2018-01-15): On Hilbert's tenth problem. Xia Univ., Jaunary 14--16, 2018. Given talk (2018-01-15): On Hilbert's tenth problem. Institute of Systems Science, Chinese Academy of Sciences, January 28-30, 2018. Given talk (2018-01-29): Problems and results on sums of squares. Conference on Combinatorics and its Applications (Harbin, May 18-20, 2018). Given talk (2018-05-19): Determinants, permutations and additive combinatorics. Wuhan Univ., June 14-17, 2018. Given talk (2018-06-15): Problems and results on sums of squares. Saint Petersburg Dept. of Steklov Math. Institute of Russian Academy of Sciencess (July 15-30, 2018). Given talk (2018-07-19): Determinants, permutations and additive combinatorics. Given talk (2018-07-20): Problems and results on sums of squares. Summer Research Institute on q-Series (Tianjin, July 25--August 15, 2018). Given talk (2018-08-14): Historical remarks on my conjectural series. Given talk (2018-08-15): On q-analogues of some identities and congruences. 2018 Conference on Number Theory and its Applications (Yan'an, August 19-22, 2018). Given talk (2018-08-20): On some determinants involving Legendre or Jacobi symbols. Courses Taught Basic Number Theory, Combinatorial Number Theory, Algebraic Number Theory; Combinatorics, Discrete Math., Mathematical Thoughts and Methods; Advanced Algebra, Modern Algebra, College Math.; Mathematical Logic, Set Theory, Recursion Theory, Model Theory. Discrete Mathematics for CS (Univ. California at Irvine, Fall, 2005). Math. 2B: Calculus (Univ. California at Irvine, Winter, 2006). Ph.D. and Postdoctor Students Yi Wang (postdoctor, 2000.9--2002.7); Ke-Jian Wu (Ph.D., 2001.2--2004.1); Qing-Lin Lu (Ph.D., 2002.2--2005.1); Zhi-Zheng Zhang (postdoctor, 2002.9--2004.7); Hao Pan (Ph.D., 2003.9--2006.7); Hui-Qin Cao (Ph.D, 2004.9--2007.7); Song Guo (Ph.D., 2004.9--2007.7); Yong Zhang (Ph.D., 2007.9--2010.7); Wei-Ping Wang (postdoctor, 2008.9--2010.7); Shan-Shan Du (Ph.D., 2010.9--2013.7); San-Ying Shi (postdoctor, 2011.2--2013.2); Dian-Wang Hu (Ph.D., 2013.9--2017.3); Guo-Shuai Mao (Ph.D., 2016.9-2019.7); He-Xia Ni (Ph.D., 2016.9-2019.7). Hai-Liang Wu (Ph.D., 2017.9-2020.7); Li-Yuan Wang (Ph.D., 2017.9-2020.7). Chen Wang (Ph.D., 2018.9-2021.7). ¡¡¡¡¡¡Home Page