Monday, 18 December 2023
2024 Online Informatics Olympiad Training, Road To NOI 2024
Sunday, 17 December 2023
Sunday, 26 November 2023
Thursday, 16 November 2023
1st ECOPRO Combinatorial Week Workshop 2023
Participants
1 | Jozsef Balogh | University of Illinois Urbana-Champaign |
2 | Felix Clemen | Karlsruhe Institute of Technology |
3 | Jialin He | The Hong Kong University of Science and Technology |
4 | Yifan Jing | Oxford University |
5 | Jeck Lim | California Institute of Technology |
6 | Weichan Liu | Chinese Academy of Sciences |
7 | Haoran Luo | University of Illinois Urbana-Champaign |
8 | Sam Mattheus | University of California San Diego |
9 | Leticia Mattos | University of Illinois Urbana-Champaign |
10 | Minghui Ouyang | Peking University |
11 | Fei Peng | National University of Singapore |
12 | Eero Räty | Umeå University |
13 | Chong Shangguan | Shandong University |
14 | Shumin Sun | University of Warwick |
15 | Tuan Tran | University of Science and Technology of China |
16 | Ethan White | University of Illinois Urbana-Champaign |
17 | Michael Wigal | University of Illinois Urbana-Champaign |
18 | Menglong Zhang | Beijing Jiaotong University |
19 | Tao Zhang | Zhejiang Lab |
20 | Yuqi Zhao | Shandong University |
21 | Xiangxiang Zheng | Hamburg University |
Monday, 6 November 2023
Meta Hacker Cup 2023 Round 3 Results
To advance to the Final Round, you must have placed amongst the top 25 contestants in this round.
Monday, 30 October 2023
Meta Hacker Cup 2023 Round 2 Results
Tuesday, 10 October 2023
2023 November/December School Holidays Online Maths Olympiad Training
Monday, 9 October 2023
Tuesday, 19 September 2023
Everywhere Unbalanced Configurations by David Conlon and Jeck Lim
Everywhere unbalanced configurations, by David Conlon and Jeck Lim
Some years ago I blogged about the following question of Yaakov Kupitz
What is the smallest number C such that for every configuration of n points in the plane there is a line containing two or more points from the configuration for which the difference between the number of points on the two sides of the line is at most C?
Kupitz asked, in particular, if every point set has a line through at least two of its points which is balanced in the sense that the number of points on either side differ by at most some fixed constant c. David Conlon and Jeck Lim showed that if you allow pseudolines rather than lines, the answer is no!
Kupitz’s question extends to pseudolines where it can be formulated using the method of allowable sequence of permutations introduced by Goodman in Pollack. The best known upper bound C = O(log log n) was proved by Rom Pinchasi and Rom’s proof uses the method of allowable sequence of permutations and applies to pseudolines. Conlon and Lim’s proof shows that for pseudolines, C = Ω(log log n) .
Congratulations David and Jeck!
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Some papers by Lim Jeck on ArXiv