Tsing Ch’a Sessions 清茶会

To promote interdisciplinary interaction between different faculty members and students on the campus, a weekly meeting has been organized by our postdoc Jialiang Yan since September 2023, called Tsing Ch’a Sessions (清茶会). Its slogan “know thyself and let others know you better.”

■Schedule for 2022-2023 academic year (Autumn)

DateSpeaker
2024 FEB 29杜鹏昊 Penghao Du
2024 MAR 07江峰 Feng Jiang,樊瑞 Rui Fan
2024 MAR 14储明亮 Mingliang Chu
2024 MAR 21杨思思 Sisi Yang
2024 MAR 28王威 Wei Wang
2024 APR 11Søren Brinck Knudstorp, 杨曦 Xi Yang
2024 APR 18欧阳文飞 Wenfei Ouyang
2024 MAY 09张力竹 Lizhu Zhang
2024 MAY 16何清瑜 Qingyu He, 王逸骞 Yiqian Wang
2024 MAY 23王威 Wei Wang
2024 MAY 30江峰 Feng Jiang, 杨曦 Xi Yang
2024 JUN 06Yichen Zhao

■Current Sessions

2024 Mar 28 14:00-15.30 Wei Wang (Tsinghua University) Towards a Logical Approach to AI-Driven Recommendations

In the digital era, users encounter an endless stream of recommendations. The development of recommendation algorithms in AI has attracted extensive attention, yielding a substantial body of literature. However, the contribution of logic has been minimal. In this talk, we propose a new recommendation logic (RL) to study the reasoning behind recommendations, emphasizing their basis in users’ revealed preferences. We explore the expressivity of RL by introducing a new notion of bisimulation and translating RL into a 3-variable fragment of a two-sorted first-order logic. We show that RL-models have the tree model property and that their model-checking problem can be solved in polynomial time, for which we propose an algorithm and prove its correctness. We believe that our approach lays a foundation for AI research and has the potential to advance personalized recommendations.

This is joint work with Fenrong Liu and Sisi Yang.


2024 Mar 21 14:00-15.30 Sisi Yang (Tsinghua University) A New Semantics for Extended Argumentation Framework

The formal study of argumentation plays an important role in knowledge representation, especially in reasoning from contradictory information. Many developments build on Dung’s seminal theory of argumentation. Preference is a key concept in argumentation to represent the comparative strength of arguments, and in particular can be used to resolve conflicts between arguments. It’s essential for preferences to adapt to various scenarios rather than remaining fixed. Consequently, Modgil extended Dung’s framework to reasoning about preferences. However, this extension led to the loss of the general existences of grounded and preferred extensions. In this talk, I will begin with an introduction to Dung’s abstract argumentation framework and semantics, followed by an introduction to Modgil’s extended argumentation framework and semantics. Then I will explain the limitations of Modgil’s semantics. At last, I will present our new semantics based on the extended argumentation framework, which preserves the semantic properties of Dung’s argumentation framework.

This is a joint work with Yan Zhang. 


2024 Mar 14 14:00-15.30 Mingliang Chu (Tsinghua University) Different Interpretations of Ockham’s Ascent and Descent Rules

The differing views on individual terms prompt us to consider Ockham’s rules of ascent and descent from various perspectives. Firstly, interpreting individual terms as elements within the domain of individuals, we see the ascent and descent rules as part of the quantification theory in first-order logic. Secondly, adopting Quine’s approach, which views individual terms as a specific kind of predicate, we interpret the rules within the tradition of the Two-Classes Theory. We believe this interpretation aligns more closely with Ockham’s original intent. Moreover, from this viewpoint, the ascent and descent rules closely coincide with the pattern of monotonic reasoning that represents ‘predicate substitution‘. Finally, to ensure the surface syntactic structure remains unchanged, we draw upon Russell’s theory of descriptions, interpreting individual terms as collections of properties. We will demonstrate that, within the framework of generalized quantifiers, the ascent and descent rules constitute a form of monotonic reasoning.


2024 Mar 7 14:00-15.30 Feng Jiang (Tsinghua University) Generic Absoluteness for the Chang Model

This talk will give an introduction to Woodin’s generic absoluteness theorem for the Chang model. In particular, we will show that if there exists a Woodin cardinal which is a limit of Woodin cardinals, then every set of reals in the Chang model is Lebesgue measurable. The proof presented here follows the approach developed in Paul Larson’s book The Stationary Tower.


2024 Feb 29 14:00-15.30 Penghao Du (Tsinghua University) Modal Logics of Definable Link Variations: Characterization and Satisfiability

Link variations, including link cutting, adding and rotating, are critical updating process on graphs, which play important roles in graph reasoning. Undefinable link variations and their logics have been widely studied. In [Li, 2020], Li introduced a modal logic, LLD, designed for definable link cutting. In this talk, following LLD, I will propose the logics LLA, LLR, and LLV, which respectively address definable link adding, rotating, and combinations of dynamic operations on graphs. Van Benthem-style characterization theorems for these logics will be provided. In addition, I will show that all these logics are undecidable and present decidable fragments of them.
This is a joint work with Qian Chen.


■Past Sessions

Click HERE to check the past sessions.