$\omega$ $\aleph$ $\infty$
Mathematical Logic at Fudan

## Fudan Logic Seminar 2021

### December 23

Guangyin Ma 马广胤

Time: 19:00 - 21:00. Tencent Meeting: 636-504-103

### December 2

Xiaojun Kang 康孝军

Time: 13:30 - 15:30. Tencent Meeting: 275-498-375

### November 30

Su Gao 高速

Time: 15:30 - 17:30. Location: HGW2403

#### Borel Cardinalities

The Borel reducibility hierarchy can be viewed as a way to compare the relative sizes of definable quotients of the set of real numbers. The theory of Borel reducibility has important applications and connections to classification problems in many areas of mathematics. I will review the main results of the theory of Borel reducibility and of its applications to classification problems. I will also talk about an analog of the Church-Turing thesis for models of coding objects in mathematics.

### November 10

Ming Xiao 肖鸣

Time: 13:30 - 15:30. Location: HGW2403

#### Borel chain condition

Chain condition is a class of coarse categorization of posets. In this talk we review some of applications of such conditions in the context of measure theory and theory of forcing. Then we introduce what we call the Borel chain conditions as an analogue of chain conditions in descriptive combinatorial study of Borel posets and prove some basic properties. Slides

### October 21

Yanjing Wang 王彦晶

Time: 13:30 - 15:30. Tencent Meeting ID: 361 142 180

#### Bundled fragments of first-order modal logic and its applications

Bundled fragments are the syntactic fragments of first-order modal logic where a quantifier and a modality are “bundled” together to occur in the formulas. Originated from the research on epistemic logic of know-wh, some bundled fragments have various good properties such as decidability over various classes of models. In this talk, we survey our recent work on various bundled fragments and their decidability, axiomatizations, and applications in philosophy and AI. In particular, we will sketch how the idea of the bundles can help us to understand intuitionistic logic and other intermediate logics, as one particular application. Slides

### May 11, 18, 25

Zhaokuan Hao 郝兆宽

Time: 15:00 - 17:00. Location: HGW2403

### March 11

Liang Yu 喻良，Nanjing University

Time: 18:30 - 20:30. Location: HGX402

#### MIP* = RE 介绍

2020年 Zhengfeng Ji, Anand Natarajan, Thomas Vidick, John Wright, Henry Yuen 宣称证明了 $\textrm{MIP}^*=\textrm{RE}$。即量子纠缠的多交互式验证的最优解是不可判定的。我们将简要介绍这一结果。进一步地，他们运用这一结果给出了Connes嵌入问题的一个反例。我们还将介绍Goldbring等人通过运用连续模型论以及 $\textrm{MIP}^*=\textrm{RE}$ 对于CEP给出的一个简洁的否定解答。Slides