Hong LIU, Chief Investigator (CI) of the Extremal Combinatorics and Probability Group (ECOPRO) within the Center for Mathematical and Computational Sciences at the Institute for Basic Science (IBS), has been awarded the 2025 Hall Medal at Combinatorics 2026, an international conference on combinatorics held in Naples, Italy, from May 25–29.

The Hall Medal is awarded by the Institute of Combinatorics and its Applications (ICA) to mid-career researchers who have made outstanding research contributions with substantial international impact. Recipients must have earned their Ph.D. in 2007 or later, and no more than two Hall Medals are awarded each year.

Hong LIU has made significant contributions to extremal graph theory, discrete geometry, and combinatorial number theory. Among his major achievements is the resolution in 2023 of the odd-cycle variant of the longstanding Paul Erdős–András Hajnal odd-cycle conjecture. He has also produced important results on triangle densities in graphs and other fundamental problems in combinatorics.

In its award citation, the ICA recognized not only his research accomplishments but also his contributions to education and the international combinatorics community. To date, Hong LIU has published approximately 70 papers, primarily in leading international journals. He has broadened access to advanced combinatorics through publicly available lecture notes and recorded courses, and has actively fostered international collaboration through his leadership of the ECOPRO research group at IBS.

The Hall Medal citation states that, “In view of his extensive quality research with substantial international impact, we believe that Hong LIU is highly qualified to receive the prestigious Hall Medal of the ICA.”

[Photo] Hong LIU receives the 2025 Hall Medal at Combinatorics 2026 in Naples, Italy.