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 (from September 2023): Junhua Yu, Chenwei Shi, Wei Wang, Jialiang Yan, Penghao Du.
■Schedule for 2023-2024 academic year
| Date | Speaker |
|---|---|
| 2024 SEP 04 | Thomas Studer |
| 2024 SEP 12 | Yuan Xu |
| 2024 SEP 28 | Xuefeng Wen |
| 2024 OCT 24 | Natasha Dobrinen |
| 2024 OCT 31 | Johan van Benthem |
| 2024 NOV 05 | Lev Beklemishev |
| 2024 NOV 07 | Hans van Ditmarsch |
| 2024 DEC 05 | Xiaolu Yang |
■Current Events
2024 Dec 05 15:15-16:45 Xiaolu Yang (杨小璐, Tsinghua University) Early Linguistic Knowledge: Evidence from Experimental Studies of Language Perception and Comprehension in Mandarin-learning Toddlers
Early language acquisition research provides a unique perspective to understanding how children acquire language. One question concerns when children display specific abstract linguistic knowledge early in development. The other is how children break into a particular language (i.e. their mother tongue), assuming the availability of innate linguistic knowledge like Universal Grammar. In this talk, I will report some young children’s perception and comprehension findings that attempt to provide answers to these important questions from a perspective of L1 acquisition of Mandarin Chinese. I will focus on Mandarin-learning toddlers’ syntactic categorization, distinction of differing verb types and processing of function words, trying to show their early sensitivity to very subtle syntactic and semantic aspects of linguistic forms and structures.
2024 Nov 07 16:00-17:30 Hans van Ditmarsch (University of Toulouse) Distributed Knowledge Revisited
We review the history and some recent work on what is known since the 1990s as distributed knowledge. Such epistemic group notions are currently getting more and more attention both from the modal logical community and from distributed computing, in various settings with communicating processes or agents. The typical intuition is that if a knows p, and b knows that p implies q, then together they know that q: they have distributed knowledge of q. In order to get to know q they need to share their knowledge. We will discuss: (i) the complete axiomatization, (ii) why not everything that is distributed knowledge can become common knowledge, (iii) the notion of collective bisimulation, (iv) distributed knowledge for infinitely many agents, (v) the novel update called resolving distributed knowledge and some variations (and its incomparable update expressivity to action models), (vi) distributed knowledge that is stronger than the sum of individual knowledge (where the relation for the group of agents is strictly contained in their intersection), (vii) common distributed knowledge and its topological interpretations, (viii) dynamic distributed knowledge, a version of the semantics ensuring that what is distributed knowledge becomes common knowledge, and the axiomatization, expressivity and bisimulation characterization of this logic.
2024 Nov 05 19:00-20:30 Lev Beklemishev (Russian Academy of Sciences) Periodic frames
Polymodal provability logic GLP is incomplete w.r.t. Kripke frames. It is known to be complete w.r.t. topological semantics, where the diamond modalities correspond to topological derivative operations. However, the topologies needed for the completeness proof are highly non-constructive. The question of completeness of GLP w.r.t. natural scattered topologies on ordinals is dependent on large cardinal axioms of set theory and is still open. So far, we are lacking a useable class of models for which GLP is complete.
In this paper (joint work with Yunsong Wang) we define a natural class of countable general topological frames on ordinals for which GLP is sound and complete. The associated topologies have been introduced by Thomas Icard in 2011. In addition, we specify a suitable algebra of subsets of an ordinal closed under the boolean and topological derivative operations. These algebras are based on the notion of a periodic set of ordinals generalizing that of an ultimately periodic omega-word.
2024 Oct 31 16:00-17:30 Johan van Benthem (Stanford&Tsinghua&University of Amsterdam) Connecting Different Logics: Translation and Tracking
Many members of the crowd of modern logical systems look very different qua syntax and semantics, but how much unity is there when we look ‘under the hood’ of their engines? I start with some significant examples of translation and other forms of reduction between logical systems, some obvious, some quite surprising. As a special interest item, I will discuss ‘tracking’ of dynamic updates in different logics, taking the case of logics for analyzing games as a running example.
Reference:
- J. van Benthem, ‘Implicit and Explicit Stances in Logic’, Journal of Philosophical Logic, 2018, https://pure.uva.nl/ws/files/85565602/Benthem2019Article_ImplicitAndExplicitStancesInLo.pdf
- J. van Benthem, ‘Tracking Information’, in K. Bimbó, ed., Michael Dunn on Information–Based Logics, Springer, Dordrecht, 363–389.
- J. van Benthem, ‘Game levels, Game logics, Translations, Tracking, and More’, working paper, ILLC, University of Amsterdam.
2024 Oct 24 16:00-17:30 Natasha Dobrinen (University of Notre Dame) Big Ramsey degrees and logic
The Infinite Ramsey Theorem states that given positive integers m and r, given a coloring of all m-element subsets of the natural numbers into r colors, there is an infinite set of natural numbers such that all of its m-element subsets have the same color. Following Sierpinski’s work in the 1930’s on colorings of finite linear orders as subsets of the rationals, the area of big Ramsey degrees seeks to understand when and to what extent the Infinite Ramsey Theorem extends to infinite structures. This talk will introduce big Ramsey degrees, demonstrate known characterizations, and discuss methods from set theory and computability applied in their study.
2024 Sep 28 (SAT) 16:00-17:30 Xuefeng Wen (文学锋, Sun Yat-Sen University ) Conditionals, Modals, and Validity in Contexts
We provide a semantics for a language containing indicatives and epistemic modals, which are elusive in formal semantics. The main idea is to evaluate a formula at a world in a context. An indicative is true at a world in a context if its consequent is true at the world in the new context updated by its antecedent in the old context. An epistemic necessity is true at a world in a context if it is true at all worlds in the context. Armed with the semantics, we define a ternary notion of validity, by which an inference is not valid per se, but valid under a set of assumptions, which are used to specify the context. The ternary notion of validity is meant to give a unified solution to several puzzles concerning indicatives and epistemic modals.
2024 Sep 12 16:00-17:30 徐源 (北京理工大学) 人工智能前沿技术及其社会应用
当前，人工智能技术的飞速发展深刻的影响着社会变革，在赋能千行百业的同时，也为社会科学领域带来了前所未有的机遇。尤其是以大模型为代表的生成式人工智能展现出了强大的能力，这些技术不仅在社会科学的理论研究中开辟了新领域，还为解决复杂社会问题提供了新的工具。本次报告，将从人工智能、哲学、传播学等跨学科视角来探讨人工智能前沿技术、行业最新的典型应用，以及其中带来的安全和伦理问题，旨在引起大家的讨论，启发对于人工智能前沿技术向前的想象力和向后的反思力。
2024 Sep 04 16:00-17:00 Thomas Studer (University of Bern) Non-wellfounded and cyclic proofs
Non-wellfounded and cyclic proofs provide a formal counterpart to proofs by infinite descent. So, proofs of this kind are helpful for logics dealing with inductive (and coinductive) definitions. This includes systems of arithmetic (induction over the natural numbers) and modal logics with fixed points (common knowledge and temporal operators). In this talk, I will introduce non-wellfounded and cyclic proofs and study their proof-theoretic properties.
■Past Events
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