To promote interdisciplinary interaction between different faculty members and students on the campus, a weekly meeting has been organized by our postdoc Yinlin Guan since September 2020, called Tsing Ch’a Sessions (清茶会). Its slogan “know thyself and let others know you better.”
■Schedule for 2022-2023 academic year (Spring)
| Date | Speaker |
|---|---|
| 2023 Feb 23 | Feng Jiang 江峰 |
| 2023 Mar 02 | Rui Fan 樊睿 |
| 2023 Mar 09 | Lizhu Zhang 张力竹 |
| 2023 Mar 16 | Zhenkun Hu 胡振坤 |
| 2023 Mar 23 | Qingyu He 何清瑜 |
| 2023 Mar 30 | Qian Chen 陈谦 |
| 2023 Apr 06 | Fengxiang Cheng 成凤祥 |
| 2023 Apr 13 | Mingliang Chu 储明亮 |
| 2023 Apr 20 | Xuan Li 李旋 |
| 2023 May 13 | Kaibo Yao 姚博凯 |
| 2023 May 18 | Xiaoxiao Fu 付小轩 |
| 2023 May 25 | Dazhu Li 李大柱 |
| 2023 Jun 01 | Penghai Du 杜鹏昊 |
■Current Sessions
2023 June 1 14:00-15:30 Penghai Du 杜鹏昊 (Tsinghua University): Logic of Link Variations
In this talk, we investigate dynamic modal operators containing cutting, adding and rotating, which have the ability to modify the accessibility relation of a model at both local and global levels. To begin with, we will provide motivation behind this research by exploring the connections between graph games, knowledge graphs, and social networks. We will then introduce the language and semantics used in the logic of global/local link variations, and proceed to show the axiomatization of these logics in its hybrid version, including details about its completeness proof. Furthermore, we will present our research findings on model checking and undecidability results for these logics. Finally, we will conclude by summarizing the key insights gained from our research, and suggest questions for further exploration. This is joint work with Qian Chen.
2023 Apr 20 14:00-15:30 Xiaoxuan Fu 付小轩 (China University of Political Science and Law): Modal Logic with Counting: Dynamic and Axiomatic Aspects
Numerical comparisons in natural language combine logical and arithmetical features. There have been many attempts to combine them with the language of first-order logic. However, the resulting logic is quite complex, so it is better to look into some small languages such as modal logic with counting ML(#) (see van Benthem & Icard 2021). In this talk, I will introduce the dynamic and axiomatic aspects of ML(#) by presenting several kinds of model updates that can use reduction axioms and showing that certain PDL constructions cannot be defined in the basic ML(#). I will also discuss the axiomatization of ML(#) with respect to different frame classes, including image-finite frames and arbitrary frames.
2023 Apr 20 14:00-15:30 Xuan Li 李旋 (Tsinghua University): 量化模态逻辑研究中个体的跨世界同一问题
量化模态逻辑中有从言（de dicto）和从物（de re）两种量化模态公式，而对于其中从物模态公式的语义探讨中涉及到了个体的跨世界同一问题，包括同一个体如何存在于不同的世界之中，个体与性质的关系等等。
克里普克和大卫·刘易斯各自给出了不同的语义理论，但是都使得个体的跨世界同一问题以不同的形式呈现出来。艾伦·海森（Allen Hazen）和曼弗雷德·卡普弗（Manfred Kupffer）基于对应物理论，给出了一种新的语义刻画。基于这一刻画，我们探讨克里普克和刘易斯理论中产生的问题。
2023 Apr 13 14:00-15:30 Mingliang Chu 储明亮 (Tsinghua University): 自然逻辑视域下奥卡姆指代模式中的上升规则
我们将以一种全新的视角来解析奥卡姆指代模式中的上升规则。指代模式是奥卡姆人称指代理论中关于普通命题（common propositions）和分立命题（discrete suppositions）之间推理关系的子理论，包括上升（ascent）和下降（descent）两个规则。指代模式的给出是用于判定三种类型的人称指代：确定指代（determinate supposition）、周延模糊指代（distributed and confused supposition）和仅仅模糊指代（merely personal supposition）。从上世纪五六十年代起，学界涌现出一批学者，如，博纳（P. Boehner，1952）、尼尔夫妇（Kneale, William & Martha, 1962）、马修斯（G.B. Matthews, 1964，1973）、斯科特（T. K. Scott, 1966）等，尝试用现代逻辑已有成果来重新诠释指代模式，例如，将指代模式视作为词项主义逻辑的量化理论（the quantification theory of terminist logic）。然而，这些看法主要是围绕指代模式中的下降规则给出的，至于指代模式中的另一部分：上升规则，则鲜有人问津。这里，我们将借助自然逻辑单调推理的思想来重新解读指代模式中的上升规则。
2023 Apr 06 14:00-15:30 Fengxiang Cheng 成凤祥 (Tsinghua University): A fresh perspective on norms in deontic logic
Deontic logic concerns notions such as “duty”, “permission”, and so on according to norms. Existing works primarily focus on establishing a proper logic for these notions. Nevertheless, a proper understanding of norms is seldom pursued. “What is a norm?” “How are agents’ duties and permissions derived from norms?” We believe that to come to grips with the meaning of the keyword “ought” in deontic logic, a proper understanding of these questions is unavoidable. In this talk, we confront these questions by proposing a way of understanding norms. We also make a first attempt to formalize our understanding and discuss several related issues.
2023 Mar 23 14:00-15:30 Qian Chen 陈谦 (Tsinghua University): Generalized Separated Topological Spaces and its modal logic
2023 Mar 23 14:00-15:30 Qingyu He 何清瑜 (Tsinghua University): 公共知识与函数依赖逻辑
函数依赖逻辑（LFD）是由Baltag和van Benthem提出的一种刻画依赖性关系的逻辑。LFD和认知逻辑之间有着紧密的联系，LFD中的算子都可以在认知逻辑中找到与之对应的认知算子。例如，LFD中的本地依赖算子对应认知逻辑中的分布式知识算子。但公共知识算子在LFD中并没有明显的对应。在这次报告中，我们将尝试给出公共知识算子在LFD框架中的解释，并通过添加公共知识算子对LFD的语言进行扩充。此外，我们会讨论扩充后的语言的表达力问题。这是与石辰威和陈谦合作的工作。
2023 Mar 16 14:00-15:30 Zhenkun Hu 胡振坤 (Tsinghua University): 《荀子·天论》的文本书写模式探赜
书面文本背后的书写模式反应了人类思维的本质规律。在中国古代，文体学的诞生标志着人们开始对不同文本所反映出的不同模式划分逐渐产生自觉，刘勰、吴讷、徐师曾等理论家阐述了各自对不同文体模式的划分标准，但他们的理论停留于哲学理论阶段，并未对某种文体文章本身的内部形式结构做详细梳理。西方汉学家如瓦格纳、麦笛、耿幽静等人同样发现了中国先秦哲学文本的书写遵循着一定的模式，他们或从某一文本单元，或从文章整体来探索文本内部的形式结构和组成肌理，但他们的研究仍有很多地方需要商榷。我们的工作在古今中外成果的基础上，以《荀子·天论》作为切入点，试图对先秦“论证性”文本的典型代表《荀子》做全面的文本分析，来发现其文本内部的书写模式、组成规律以及是否具有逻辑推理。
2023 Mar 09 14:00-15:30 Lizhu Zhang 张力竹 (Tsinghua University): A study on a propositional probability logic without iterations of the probability operators
In this presentation, I will introduce an interaction between mathematical logic and probability which is a logic enriches propositional logic with a list of probability operators. As the semantics, I will introduce a class of models that combine properties of Kripke models and probabilities defined on sets of possible worlds. And the axiomatization is infinitary which contains an infinitary rule with countable many premisses and one conclusion.
2023 Mar 02 14:00-15:30 Rui Fan 樊睿 (Tsinghua University): Compare three deontic logics for rationality in games
Game Theory considers about behaviour of rational agency and their optimal strategies towards their best benefit. Deontic Logic is about the reasoning of normative concepts such as obligation and permission. They looks very different seemingly. But if we consider obligation and permission respectively providing necessary and sufficient conditions for rationality in games, then we can analyze what players ought to do in a strategic game. I will focus on three deontic logics which adopting the above perspective and discuss their relationships: Van Benthem’s “Minimal Deontic Logic”, Anglberger et al.’s “Obligation as Weakest Permission”, and Trypuz and Kulicki’s “Deontic Boolean Action Logic”. Although MDL, OWP and DBAL embody the same core principle, MDL and OWP view different philosophical commitments regarding rational obligation and permission, and DBAL can be embedded into MDL.
2023 Feb 23 14:00-15:30 Feng Jiang 江峰 (Tsinghua University): 对比两种依赖性逻辑
在逻辑学的诸多应用场景中，变量之间的依赖性是一个非常普遍的现象。许多逻辑学家提出了各种不同的逻辑系统，试图形式的刻画“依赖性”这一概念，这其中包括Hintikka和Sandu提出的独立性友好逻辑（Independence Friendly Logic）、Väänänen提出的依赖性逻辑（Dependence Logic）、Baltag和van Benthem提出的函数依赖性逻辑（LFD）。本次报告将对比依赖性逻辑DL和函数依赖性逻辑LFD。这两种逻辑是非常不同的。DL是一阶逻辑的扩张，其表达力与存在二阶逻辑（existential second-order logic）等价。LFD是一阶逻辑的一个片段同时也是一种模态逻辑，所以LFD的表达力是相对受限的。判定一个DL的闭公式是否是有效式是非常复杂的，其复杂度与完整的二阶逻辑相当，因而是不可递归公理化的。但LFD有完全的形式演绎系统并且是可判定的。DL是一种非古典逻辑，排中律不是DL的有效式，但LFD是古典的。尽管如此，DL和LFD仍然具有一些共同的特征。
■Past Sessions
Click HERE to check the past sessions.
