一、日程表

二、学术报告题目与摘要

密码万花筒

王杰（北京大学）

摘要：本报告将讲述历史上的密码，文学艺术中的密码，密码学与信息论—经典密码体制，密码学与计算复杂度—公开密钥密码体制和量子时代等等内容。

Non-repeated cycle lengths and Sidon sequences

马杰 （中国科学技术大学）

Abstract: We prove a conjecture of Boros, Caro, Furedi and Yuster on the maximum number of edges in a 2-connected graph without repeated cycle lengths, which is a restricted version of a longstanding problem of Erdos. Our proof together with the matched lower bound construction of Boros, Caro, Füredi and Yuster show that this problem can be conceptually reduced to the seminal problem of finding the maximum Sidon sequences in number theory. Joint work with Tianchi Yang.

The Betti Number of Independence Complex of Ternary Graphs

吴河辉 （复旦大学）

Abstract: A graph is ternary if no induced cycle has length multiple of three. Recently, Chudnovsky, Scott, Seymour and Spirkl proved a conjecture of Kalai and Meshulam, which states that for any ternary graph, the difference of the number of odd independence sets and the number of even independence sets are at most 1. A stronger form of Kalai-Meshulam conjecture concerns the Betti number of the independence complex $I(G)$ of a ternary graph $G$. Let $b_i$ be the $i$-th (reduced) Betti number of $I(G)$, and let $b(G)$ be the sum of all betti numbers. It is conjectured that $b(G)\le 1$. We prove this conjecture. This is joint work with Wentao Zhang, a new graduate student of Fudan University.