School of Mathematical Sciences Academic Lecture [2025] No. 082
(High-Level University Development Series Report No. 1104)
Lecture Title: co-2P3-Free Graphs with No Odd Holes
Lecturer: Associate Professor Yan Wang (Shanghai Jiao Tong University)
Lecture Time: September 4, 2025 (Thursday), 15:00–16:00
Venue: Room 501, Huixing Building
Abstract: Chudnovsky, Robertson, Seymour and Thomas proved that every (odd hole, K_4)-free graph is 4-colorable and is 3-colorable if it does not contain an antihole of length 7 as an induced subgraph. In this talk, we prove a stronger result: Every (odd hole, \bar{2P3})-free graph is (ω (G)+1)-colorable, and the equality holds if and only if G contains the join of an antihole of length 7 and a clique of size ω(G)-3. This also implies that (odd hole, \bar{2P3})-free graphs are 2-divisible and perfectly divisible, which establish a conjecture of Hoàng and McDiarmid, and a conjecture of Hoàng for such graphs. This is joint work with Shuang Sun.
Lecturer's Biography: Yan Wang, Associate Professor and Doctoral Supervisor at the School of Mathematical Sciences, Shanghai Jiao Tong University, and a recipient of the National High-Level Young Talents Program. He received his Ph.D. in 2017 from the Georgia Institute of Technology under the supervision of the renowned graph theorist Professor Xingxing Yu. He was selected for the Shanghai Overseas High-Level Talent Program and leads a Young Scientists Project under the National Key R&D Program. His main research area is graph theory. He has published more than 30 high-quality papers and, in collaboration with Professor Xingxing Yu and others, proved the nearly forty-year-old Kelmans–Seymour Conjecture.
All faculty members and students are welcome to attend!
Inviter: Huang Zejun
School of Mathematical Sciences
September 1, 2025
