Time to hang up posters today: Advances in Modal Logic 2026 is happening! See https://events.illc.uva.nl/aiml2026/ for accepted papers. Early registration until 22 May. 🔷♦️💎
#logic #amsterdam #aiml #modallogic

The deadline for submission of abstracts to #IMLA (Intuitionistic Modal Logic and Applications) has been extended to 30 April. It would be great if I were to see some of you there (at least, at the banquet for that weekend's #FLoC workshops).

"Constructive and intuitionistic modal logics, and their connections with type theory and computation, remain foundationally and practically significant in computer science, logic, and related areas. These include applications in type disciplines, meta-logics for computational phenomena, and explanatory frameworks in philosophical logic. The workshop aims to explore theoretical and methodological issues at the intersection of constructive proof theory and modal semantics, as well as practical questions about which modal connectives and rules best capture computational phenomena at appropriate levels of abstraction."

**Invited speakers**
- Danel Ahman (University of Tartu, Estonia)
- Brigitte Pientka (McGill University, Montreal, Canada)
- Ranald Clouston (ANU, Canberra, Australia)
- More to be confirmed

https://sonia-marin.github.io/imla26/

#ModalLogic #IntuitionisticLogic #Logic

IMLA 26

8th Workshop on Intuitionistic Modal Logic and Applications (IMLA)
24–25 July 2026, Lisbon, Portugal
Affiliated with the Federated Logic Conference (FLoC 26)
https://sonia-marin.github.io/imla26/

Constructive and intuitionistic modal logics, and their connections with type theory and computation, remain foundationally and practically significant in computer science, logic, and related areas. These include applications in type disciplines, meta-logics for computational phenomena, and explanatory frameworks in philosophical logic. The workshop aims to explore theoretical and methodological issues at the intersection of constructive proof theory and modal semantics, as well as practical questions about which modal connectives and rules best capture computational phenomena at appropriate levels of abstraction.

**Invited speakers**
- Brigitte Pientka (McGill University, Montreal, Canada)
- Ranald Clouston (ANU, Canberra, Australia)
- More to be confirmed.

**Submissions**
We invite abstracts for contributed talks of up to *2 pages* (excluding bibliography). They may describe published work, unpublished work, or work in progress. We especially encourage submissions from students and early-career researchers.

Abstracts should be submitted via the workshop’s submission page:
https://submissions.floc26.org/imla/

(ctd)

#Logic #ModalLogic #CallForAbstracts

IMLA 26

New preprint! https://arxiv.org/abs/2601.03762 . This is our 2nd paper on the intuitionistic modal logic CK and its extensions. We look at 'duality', the relationship between Kripke semantics and universal algebra. There are various dualities in the literature, but ours has some unusual features, including our 'exploding world' which satisfies all formula, including contradictions! Dualities allow results in algebra to be ported to the modal world, as we do in the 2nd half of the paper to, for example, give a description of which classes of possible worlds can be axiomatically defined. #Logic #ModalLogic
Duality for Constructive Modal Logics: from Sahqlvist to Goldblatt-Thomason

We carry out a semantic study of the constructive modal logic CK. We provide a categorical duality linking the algebraic and birelational semantics of the logic. We then use this to prove Sahlqvist style correspondence and completeness results, as well as a Goldblatt-Thomason style theorem on definability of classes of frames.

arXiv.org
Discussing “Extended Curry-Howard Correspondence for a Basic Constructive Modal Logic” – The Updated Scholar

New preprint: Functional Causation Beyond Spacetime: A Non-Metric Framework for Temporal Structure

Can causal direction emerge from internal asymmetries rather than geometry?

📄 PDF: https://philpapers.org/rec/LENFCB
🔍 #Causality #ModalLogic #StructuralRealism #PhilosophyOfPhysics

My paper 'Semantical Analysis of Intuitionistic Modal Logics between CK and IK', with Jim de Groot and Ian Shillito, is now in its final edited preprint form: https://arxiv.org/abs/2408.00262 . I will travelling to #LICS #LICS2025 to present it in Singapore in late June. #logic #modalLogic
Semantical Analysis of Intuitionistic Modal Logics between CK and IK

The intuitionistic modal logics considered between Constructive K (CK) and Intuitionistic K (IK) differ in their treatment of the possibility (diamond) connective. It was recently rediscovered that some logics between CK and IK also disagree on their diamond-free fragments, with only some remaining conservative over the standard axiomatisation of intuitionistic modal logic with necessity (box) alone. We show that relational Kripke semantics for CK can be extended with frame conditions for all axioms in the standard axiomatisation of IK, as well as other axioms previously studied. This allows us to answer open questions about the (non-)conservativity of such logics over intuitionistic modal logic without diamond. Our results are formalised using the Coq Proof Assistant.

arXiv.org

$Trump ordered government agencies to prepare for mining the ocean floor.

Just because it is legal does not mean you should do it. Permission is not obligation.

Just say no. They have no power if you ignore them.

#JustSayNo #ModalLogic #RM3

I’m in Amsterdam, about to give a talk about proof theory for modal predicate logic at the ILLC, the home base of the modal industrial complex. I have no idea how this is going to go over, but it should be a fun ride, however it turns out.

https://consequently.org/presentation/2025/mlce-illc/

#prooftheory #modalLogic

Modal Logic and Contingent Existence — consequently.org