My work is currently supported by the** National Science Foundation** under Grant No. DMS-2153945; and in the past by the** National Science Foundation** under Grant No. DMS-1854903, and the **National Security Agency** under Grant No. H98230-09-1-0055.

My current research interests mainly focus on Hadwiger’s conjecture and its related problems; Ramsey related problems (including size of co-critical graphs and Gallai-Ramsey numbers of graphs); Erdos-Lovasz Tihany conjecture; Star edge-colorings; and Turan numbers and anti-Ramsey numbers of graphs when host graphs are planar graphs.

**Preprints **

**Multicolor bipartite Ramsey number of double stars**, (with undergraduate student Gregory DeCamillis), submitted. arXiv:2312.03670**The minimum degree of (Ks,Kt)-co-critical graphs**(with undergraduate students Ivan Casas-Rocha and Benjamin Snyder), submitted. arXiv:2311.04800**Minimizing the edges in (C4,star)-co-critical graphs**(with Gang Chen and Chenchen Ren), submitted. arXiv:2308.00674**Multicolor Ramsey number for double stars**(with undergraduate student Jake Ruotolo), submitted. arXiv:2211.03642**Every graph with no K8-4e minor is 7-colorable**(with PhD student Michael Lafferty), submitted. arXiv:2208.07338**Every graph with no K9-6e minor is 8-colorable**(with PhD student Michael Lafferty), submitted. arXiv:2209.05259**An improved lower bound for the Planar Turan number of cycles**(with Yongxin Lan), submitted. arXiv:2209.01312**Planar Turan numbers of cubic graphs and disjoint union of cycles**(with Yongxin Lan and Yongtang Shi), submitted. arXiv:2202.09216**Improved upper bounds for Gallai-Ramsey numbers of odd cycles**(with PhD students Christian Bosse, Jingmei Zhang), preprint 2018. arXiv:1808.09963**Multicolor Gallai-Ramsey numbers of C9 and C11**(with PhD student Christian Bosse), preprint 2018, arXiv:1802.06503.

**Journal Publications**

**Breaking the degeneracy barrier for coloring graphs with no Kt minor**(with Sergey Norin and Luke Postle),**Advances in Mathematics**422 (2023), 109020.**Properties of 8-contraction-critical graphs with no K7 minor**(with Martin Rolek and Robin Thomas), European Journal of Combinatorics 110 (2023), 103711.**A note on odd colorings of 1-planar graphs**(with Dan Cranston and PhD student Michael Lafferty), Discrete Applied Mathematics 330 (2023) 112-117.**Gallai-Ramsey number of odd cycles with chords**(with Yaojun Chen, Fangfang Zhang), European Journal of Combinatorics 107 (2023), 103598.**Some remarks on even-hole-free graphs**, The Electronic Journal of Combinatorics 29 (2022), P3.30.**On the size of (Kt, path)-co-critical graphs**(with Gang Chen, Zhengke Miao, Jingmei Zhang), Graphs and Combinatorics 38 (2022), 136.**A new upper bound for the chromatic number of graphs with no odd Kt minor**(with Sergey Norin), Combinatorica 42 (2022) 137–149.**On the size of (Kt,star)-co-critical graphs**(with undergraduate student Hunter Davenport, and Ph.D student Fan Yang from Shandong University), European Journal of Combinatorics 104 (2022), 103533.**The Erdos-Lovasz Tihany Conjecture — a survey**, Advances in Mathematics (China)(数学进展）51 (2022) 259–274.**Gallai-Ramsey number of even cycles with chords**(with Yaojun Chen, Fangfang Zhang), Discrete Mathematics 345 (2022), 112738.**A survey on planar Turan and anti-Ramsey number of graphs**(with Yongxin Lan, Yontang Shi), Operations Research Transactions (运筹学学报) 25 (2021) 200–216.**On the size of special class 1 graphs and (P3;k)-co-critical graphs**(with Gang Chen, Zhengke Miao, Jingmei Zhang), Discrete Mathematics 344 (2021), 112604.**On the size of (Kt, Tk)-co-critical graphs**(with PhD student Jingmei Zhang), The Electronic Journal of Combinatorics 28(1) (2021), #P1.13.**Multicolor Gallai-Ramsey numbers of C10 and C12**(with H. Lei, Y. Shi, PhD student Jingmei Zhang), Australian Journal of Combinatorics 79 (2021) 380-400.**Antimagic orientations of graphs with given independence number**(with Donglei Yang, Fangfang Zhang), Discrete Applied Mathematics, 291 (2021) 163-170.**Antimagic orientations of graphs with large maximum degree**(with D. Yang, J. Carlson, A. Owens, K. Perry, I. Singgih, F. Zhang, X. Zhang), Discrete Mathematics 343 (2020) 112123.**A note on Gallai-Ramsey number of even wheels**(with Bing Wei, Fangfang Zhang and Qinghong Zhao), Discrete Mathematics 343 (2020) 111725.**Some remarks on interval colorings of complete tripartite and biregular****graphs**(with Puning Jing, Zhengke Miao), Discrete Applied Mathematics 277 (2020) 193-197.**Antimagic orientations of even regular graphs**(with Tong Li, Guanghui Wang, Donglei Yang, C-Q. Zhang), J. Graph Theory 90 (2019) 45-53.**Extremal H-free planar grap****hs**(with Yongxin Lan, Yongtang Shi), Electronic Journal of Combinatorics 26 (2019) #P2.**A conjecture on Gallai-Ramsey numbers of even cycles and paths**(with PhD student Jingmei Zhang ), Australasian Journal of Combinatorics 75 (2019) 296-308.**Erdos-Lovasz Tihany****Conjecture****for****graphs****with forbidden holes**, Discrete Mathematics 342 (2019) 2632-2635.**Extremal Theta-free planar graphs**(with Yongxin Lan, Yongtang Shi), Discrete Mathematics 342 (2019) 111610.**Planar anti-Ramsey numbers of paths and cycles**(with Yongxin Lan, Yongtang Shi), Discrete Mathematics 342 (2019) 3216-3224.**Planar anti-Ramsey numbers of matchings****Gallai-Ramsey numbers of C7****with multiple colors**(with undergraduate student Dylan Bruce), Discrete Mathematics 342 (2019) 1191-1194.**Star chromatic index of subcubic multigraphs**(with Hui Lei, Yongtang Shi), J. Graph Theory 88 (2018) 566-576.**Clique minors in double-critical graphs**(with PhD student Martin Rolek), J. Graph Theory 88 (2018) 347-355.**Saturation numbers of Ramsey-minimal graphs**(with PhD student Martin Rolek), Discrete Mathematics 341 (2018) 3310-3320.**Star 5-edge-colorings of subcubic multigraphs**(with Hui Lei, Yongtang Shi, Tao Wang), Discrete Mathematics 341 (2018) 950-956.**Coloring graphs with forbidden minor**s (with PhD student Martin Rolek), J. Combinatorial Theory, Ser. B 127 (2017) 14-31.**Hadwiger’s conjecture for graphs with forbidden holes**(with undergraduate student Brian Thomas), SIAM J. Discrete Mathematics 31 (2017) 1572-1580.**Double-critical graph conjecture for claw-free graphs**(with PhD student Martin Rolek), Discrete Mathematics 340 (2017) 1633-1638.**Intrinsic Evolution of Truncated Puiseux Series on a Mixed-Signal Field Programmable SoC**(with Vignesh Thangavel and Ronald DeMara), IEEE Access 4 (2016) 2863-2872.**A note on weighted rooted trees**(with PhD students Talon Ward and Alex York), Discrete Mathematics 338 (2015) 2492-2494.**On the size of graphs of class 2 whose core has maximum degree tw**o (with K. M. Koh), Graphs and Combinatorics 29 (2013) 1429-1441.**Hadwiger number and chromatic number for near regular degree sequences**(with N. Robertson), J. Graph Theory 64 (2010) 175-183.**Independence number and clique minors**(with Ken-ichi Kawarabayashi), J. Graph Theory 56 (2007) 219-226.**Some remarks on the odd Hadwiger’s conjecture**(with Ken-ichi Kawarabayashi), Combinatorica 27 (2007) 429-438.**The extremal function for K_9 minors**(with Robin Thomas), J. Combinatorial Theory, Ser. B 96 (2006) 240-252.**The extremal function for K_8- minors**, J. Combinatorial Theory, Ser. B 95 (2005) 300 -317.**The chromatic index critical graphs of even order with five major vertices**(with H. P. Yap), Graphs and Combinatorics 21 (2005) 239-246.**A further extension of Yap’s construction for \Delta-critical graphs**, Discrete Mathematics 243 (2002), 283-290.**Chromatic index critical graphs of odd order with five major vertices**, J. Combin. Math. Combin. Comput. 41 (2002) 161-186.**Alternative proofs of three theorems of Chetwynd and Hilton**(with H. P. Yap), J. Combin. Math. Combin. Comput. 36 (2001) 237-246.**An extremal problem on the potentially P_k-graphic sequences**(with J-S. Li), Discrete Mathematics 212 (2000) 223-231.**On the potentially P_k-graphic sequences**(with Jiong-Sheng Li), Discrete Mathematics 195 (1999) 255-262.**The smallest degree sum that yields potentially P_k-graphic sequences**(with J-S. Li), J. Graph Theory 29 (1998) 63-72.**The Erdös-Jacobson-Lehel conjecture on potentially P_k-graphic sequences is true**(with J-S. Li and R. Luo), Science in China, Ser. A 41 (1998) 510-520.**The Erdös-Jacobson-Lehel conjecture about potentially P_k-graphic sequences**(in Chinese) (with J-S. Li and P. Wang), J. China Univ. Sci. Tech.