Initiated by the center’s students and researchers in 2019, the Tsinghua Logic Salon has quickly grown into a lively platform for try-outs and exchanges of new ideas. Researchers in various fields of logic are invited to present their latest research, as well as the challenges that they see. Every participant is encouraged to engage in discussions and exchange of perspectives. Each session lasts for 1.5 hours in total, with 30 minutes of discussion included.
Organizing Committee (since September 2023): Junhua Yu, Chenwei Shi, Wei Wang, Jialiang Yan, Penghao Du.
■ Schedule for 2024-2025 academic year (Spring)
| Date | Speaker |
|---|---|
| 2025 Feb 20 | Kazuyuki Tanaka |
| 2025 Feb 27 | Benedikt Loewe |
| 2025 Mar 20 | Youan Su |
| 2025 Mar 27 | Jieting Luo |
| 2025 Apr 24 | Huaqing Cheng |
| 2025 May 08 | Wei Zhu |
| 2025 May 10 | Xueyin Zhang |
| 2025 May 22 | Eleonora Cresto |
| 2025 May 29 | Daniyar Shamkanov |
■ Current Events
2025 Mar 20 16:00-17:30 Youan Su (苏有安 Liaoning University) Craig’s Interpolation in Intuitionistic Epistemic Logic IEL with Distributed Knowledge
This talk will focus on the Craig interpolation theorem, including its meaning, history, and applications. We will present a standard proof-theoretic approach known as Mahara’s method to demonstrate the proof of this theorem. The foundational system under consideration is a first-order intuitionistic epistemic logic IEL with distributed knowledge. We will demonstrate the Craig interpolation theorem in the system that does not include function symbols. The contents discussed are based on a collaborative work with Katsuhiko Sano and Ryo Murai.
2025 Feb 27 18:00-19:30 Benedikt Löwe (University of Hamburg and University of Cambridge) Modal logics of model constructions
This is a survey talk about modal logics of model constructions with a particular emphasis on modal logics of forcing. We shall discuss what we can learn from them, how we determine such a modal logic, and what the most relevant open questions are.
About the speaker: Professor Benedikt Löwe is a mathematician, logician, and philosopher based at the Universities of Hamburg and Cambridge. For decades he has been working in mathematical logic (especially set theory) and philosophy of mathematics. His personal webpage is https://www.math.uni-hamburg.de/home/loewe/index.html
2025 Feb 20 Kazuyuki Tanaka (Beijing Institute of Mathematical Sciences and Applications, 北京雁栖湖应用数学研究院) On collapsing phenomena of the alternation hierarchy of modal μ-calculus
Modal μ-calculus, introduced by D. Kozen, is a propositional modal logic extended with greatest and least fixpoint operators. In general, the μ-calculus is much more expressive than modal logic. The alternation hierarchy of μ-formulas is generated by calibrating the entanglement of the fixed-point operators in a μ-formula.
Alberucci and Facchini [1] demonstrated that the alternation hierarchy of the modal μ-calculus collapses to the alternation-free fragment over transitive frames (for K4) and further to modal logic over equivalence relations (for S5). We extend their results to a broader range of frames, and then characterize such collapsing phenomena in terms of special μ-equations.
Furthermore, we apply our findings to epistemic logics, investigating how the alternation hierarchy behaves in systems such as S4.2, S4.3, S4.3.2, and S4.4. From this perspective, we analyze degrees of ignorance in these logics, providing insights into their epistemic structures.
This research is conducted in collaboration with Dr. Leonard Pacheco (Institute of Science, Tokyo), and an earlier version of this work was presented in [2].
[1] L. Alberucci and A. Facchini. The modal μ-calculus hierarchy over restricted classes of transition systems. J. Symbolic Logic 74 (4) 1367 – 1400, 2009.
[2] L. Pacheco and K. Tanaka. The Alternation Hierarchy of the μ-calculus over Weakly Transitive Frames. WoLLIC 2022, LNCS 13468, 207-220, 2022.
田中一之教授博士毕业于美国加州大学伯克利分校，曾就职于东京工业大学和东北大学，并指导15位博士生和50名硕士生，2022年正式入职BIMSA。他是数理逻辑和计算理论领域的国际知名学者，在反推数学和二阶算术领域开创了新的研究方法，如WKLo的田中嵌入定理和守恒结果的田中公式，取得了一系列奠基性的成果，并将这一研究方向引入日本，将日本的数理逻辑研究推向了世界水平。田中一之教授还致力于模态mu演算，认知逻辑，随机博弈树等交叉领域的研究。
■Past Events
Click HERE to check the past events.
