Confirmed speakers

Ahti-Veikko Juhani  Pietarinen (Hong Kong Baptist University)

Linear Philosophy of Mathematics

In the philosophy of mathematics, we should distinguish notions of proof and truth that are attuned to actual mathematical practice, including how proofs use and reuse information. Neither purely classical nor purely constructive accounts fully capture this resource sensitivity. Linear logic (and, more broadly, “linear” mathematics) offers a refinement of constructive viewpoints that relates classical and constructive fragments via categorical semantics (★‑autonomous categories) and makes resource‑sensitive reasoning explicit. A key practical question is the permissibility of duplication: in the absence of exponentials, propositions behave as consumable resources, whereas the exponential modalities (!, ?) reintroduce comonadic structure that supports controlled weakening and contraction. Categorially, this corresponds to the availability of comonoid (and monoid) structure and of diagonals A → A ⊠ A only when licensed by exponentials. Seen in this light, familiar diagonal constructions and paradoxes are mediated by modalities that govern duplication and discard. The Chu construction further links these themes by a Socratic pairing of proofs and refutations within a single ★‑autonomous setting, bringing the polarity of verification and falsification into focus and connecting to dialogical validation. I close by noting anticipations in Peirce’s writings (1901–1910) of both dialogical conceptions of truth and a non‑apriorist stance toward structural proof rules, particularly the regulation of duplication (iteration) and discard (deiteration) via dialogic empowerment.

Emiliano Lorini (IRIT, CNRS, Toulouse University)

An Epistemic Theory of Deductive Arguments

The main objective of this work is to show how a notion of deductive argument and, consequently, a formal theory of deductive arguments, can be entirely reconstructed within an epistemic logic framework by adopting a concrete semantics based on belief bases, as an alternative to the standard abstract semantics grounded in multirelational structures (also known as Kripke models). This approach makes it possible to explicitly represent the notion of deducibility, as well as the premises and conclusion of an argument, and to naturally extend the theory of deductive argumentation to a multi-agent setting and to higher-order arguments (i.e., arguments whose premises or conclusions concern the beliefs of other agents). It also helps to clarify the relationship between the notion of deductive argument and the notion of reason as studied in formal epistemology. During the talk, I will also present several results concerning the expressiveness, axiomatization, and decidability of an epistemic language interpreted over this semantics, in which the notion of deductive argument can be formally expressed.

Thomas Ågotnes (University of Bergen & Shanxi University)

On the Logic of Anonymous Public Announcements

I formalise the notion of an anonymous public announcement in the tradition of public announcement logic. Such announcements can be seen as in-between a public announcement from “the outside" (an announcement of ϕ) and a public announcement by one of the agents (an announcement of Kaϕ): we get more information than just ϕ, but not (necessarily) about exactly who made it. Even if such an announcement is prima facie anonymous, depending on the background knowledge of the agents it might reveal the identity of the announcer: if I post something  on a message board, the information might reveal who I am even if I don’t sign my name. Furthermore, like in the Russian Cards puzzle, if we assume that the announcer’s intention was to stay anonymous, that in fact might reveal more information. In this talk I first look at the case when no assumption about intentions are made, in which case the logic with an anonymous public announcement operator is reducible to epistemic logic. I then look at the case when we assume common knowledge of the intention to stay anonymous, which is both more complex and more interesting: in several ways it boils down to the notion of a “safe" announcement (again, similarly to Russian Cards). Main results include formal expressivity results and axiomatic completeness for key logical languages. The talk is based on joint works with Rustam Galimullin, Ken Satoh and Satoshi Tojo.

Yì Nicholas Wáng (Shandong University)

Skill Assessment: A Modal Logic Approach

We introduce a weighted epistemic logic designed to reason about the interplay between an agent's beliefs and their epistemic capabilities. By employing implicit weights for belief operators alongside explicit proficiency formulas, our framework formally links belief states to underlying skills. We generalize the concept of weights to fuzzy skill sets, thereby allowing the logic to accommodate uncertainties in similarity relations and agents' skill profiles. This logic establishes a natural structural connection to classical Pawlak rough sets and fuzzy rough sets. We provide a sound and complete axiomatic system for the proposed logic. Furthermore, we introduce an extension featuring quantified updates to formalize Skill Assessment Problems (SAP) and Competency Verification Problems (CVP). In the context of rough sets, these tasks represent a variant of the attribute selection problem. Our analysis of model checking reveals a tiered complexity profile: the basic logic is efficiently solvable in P (polynomial time), while the extended logic with updates is co-NP-complete. This is joint work with Xiaolong Liang.

Confirmed Tutorial:

Logics for strategic reasoning about socially interacting rational agents, presented by 

Valentin Goranko (Stockholm University)

Click here for more detail.