presentations
Finite-variable Goldblatt-Thomason Theorems
Oct. 20th Talks by Haiting Wang and Qianli Zeng
Center for Logic, Language and Cognition, Peking University · Teaching Building No. 2, Room 411 · 20 October 2026
Abstract
We characterize the frame definability of modal theories in which each formula contains at most n propositional variables. We introduce algebraic n-localizations and show that definability is characterized by closure under generated subframes, disjoint unions, and surjective bounded images, together with reflection of n-localizations. This provides a uniform algebraic framework for known results and new applications, including optimal variable bounds for bounded out-degree, common-successor confluence, density, width, and weak connectedness. We also address the global modality and relative definability over finite transitive frame classes.
The Barcan Formula in First-Order Intuitionistic Modal Logics S5
Ookayama Logic Seminar Summer Intensive Seminar, 24–25 September 2026 (大岡山ロジックセミナー夏期集中セミナー)
Institute of Science Tokyo (東京科学大学), online · 25 September 2026
Joint presentation with Dr. Youan Su.
Joint work with Dr. Youan Su and Dr. Huaqing Cheng.
Goldblatt-Thomason Theorems of Bundled Fragments
Colloquium Logicum 2026
Institute of Mathematics, University of Würzburg · 22 September 2026
When Necessity Can Be Defined in Terms of Noncontingency
Salzburg Conference for Young Analytic Philosophy (SOPhiA 2026)
University of Salzburg · 3 September 2026
Abstract
On when necessity can be defined in terms of noncontingency.
A Jónsson-Tarski-Goldblatt Representation and Frame Definability for Noncontingency Logic
Scandinavian Logic Society Symposium (SLSS 2026)
Technical University of Denmark (DTU) · 22 August 2026
The Elimination of Direct Self-Reference
The 16th National Conference on Modern Logic
Shandong University · 29 October 2022
Joint work with Prof. Ming Hsiung.
The Elimination of Direct Self-Reference
Annual Conference of Philosophy of Mathematics in China
Sun Yat-sen University · 3 September 2022
Joint presentation with Prof. Ming Hsiung.