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:
Junhua Yu, Chenwei Shi, Wei Wang, Han Xiao, Haoxuan Luo. (From June 2025 to Now)
Junhua Yu, Chenwei Shi, Wei Wang, Jialiang Yan, Penghao Du. (From September 2023 to June 2025)
■ Current Events
Many current hyperintensional logics with a semantics using truthmaking, ‘support’, or teams fit in a long tradition of set-lifting classical logical systems. I will add some older examples dating back to around 1980, stressing the essentially modal character of this move. Next I will discuss the mathematical framework of ‘Complex Algebra’ that lies behind set-lifting. Finally, I introduce two faithful translations of known hyperintensional logics into classical modal logics. I conclude with some discussion of the many new issues these connections raise for both kinds of logical system.
About the speaker: Johan van Benthem is a University Professor emeritus of pure and applied logic at the University of Amsterdam, Henry Waldgrave Stuart Professor of Philosophy at Stanford University, and Jin Yuelin Professor of Logic at Tsinghua University Beijing. He has worked in modal logic, temporal logic, logical semantics and syntax of natural language, as well as dynamic logics of information, computation, and agency. He was the founding director of the ‘Institute for Logic, Language and Computation’ (ILLC) at the University of Amsterdam, and the first Chair and First Honorary Member of the European Association for Language, Logic and Information (FoLLI). His published books include “The Logic of Time” (1983), “Modal Logic and Classical Logic” (1985), “Essays in Logical Semantics” (1986), “Language in Action” (1991), and “Exploring Logical Dynamics” (1996). His current main interest is the theme of intelligent interaction, at the interface of logic, computer science, cognitive science, and game theory, with new books “Modal Logic for Open Minds” (2010), “Logical Dynamics of Information and Interaction” (2011) and “Logic in Games” (2014). Published some 400 papers. Editor of Handbooks of “Logic and Language” (1997), “Modal Logic” (2006), “Spatial Logics” (2007), and “Philosophy of Information” (2008). He is a member of the Academia Europaea (1991), the Royal Dutch Academy of Arts and Sciences (1992), Institut International de Philosophie (2001), and Hollandsche Maatschappij der Wetenschappen (2002). In addition, he is also a foreign member of the American Academy of Arts and Sciences. In 1996 he received the Dutch national NWO Spinoza Premium for his total research.
A classical result of Bergstra and Tucker states that every finitely generated computable algebra admits a finite presentation after expanding the signature with finitely many auxiliary computable operations. They also prove that every computably enumerable algebra can be embedded into a finitely presented algebra by adding new operations to the extended algebra. These results led Bergstra and Tucker, and independently Goncharov, to ask in the late 1970s whether every finitely generated computably enumerable algebra admits a finite presentation by either equations or quasi-equations in an expansion without extending the domain. The equational case of this problem was fully resolved in the 1988-2014 period.
About the speaker: Bakh Khoussainov 现任电子科技大学算法与逻辑实验室主任，研究领域涵盖数理逻辑与理论计算机科学。他是新西兰皇家学会会士、欧洲科学院院士，并入选中国国家级人才计划（长江学者讲席学者）。他曾获欧洲理论计算机科学协会 Nerode 奖、洪堡奖，以及 STOC 2017 最佳论文奖。
