Date Monday, 28 September 2026, at 16:00 CEST (UTC+2) on Zoom
Speaker Juha Kontinen (Professor of Mathematics, University of Helsinki)
Title Aspects of Coherence in Dependence Logic
Abstract
Dependence logic extends first-order logic with dependence atoms, which express
that the value of a variable is functionally determined by other variables. Team
semantics gives dependence logic a second-order flavour, and even
quantifier-free dependence logic formulas can have an NP-complete model-checking
problem. This motivates the study of syntactic conditions under which model
checking becomes tractable.
The talk starts with a brief introduction to team semantics and dependence logic, and then focuses on coherence, a notion introduced by Jarmo Kontinen to capture when the satisfaction of a formula can be determined by satisfaction by its small subteams. We show that, for quantifier-free formulas, coherence is precisely equivalent to first-order rewritability. We also study the complexity of deciding coherence, obtaining strong undecidability results for dependence logic and a precise complexity classification for propositional dependence logic.
The talk is based on joint work with Timon Barlag, Nicolas Fröhlich, Miika
Hannula, Phokion G. Kolaitis, Arne Meier, and Jouko Väänänen:
https://arxiv.org/abs/2605.31269
The new Executive Board will oversee the activities of the Scandinavian Logic Society and work to support research, education, and collaboration in logic across the Nordic countries.
]]>15th October 2026
https://www4.uib.no/en/research/research-groups/research-group-for-logics-and-ai
More information and official application requirements can be found at the job announcement URL above.
We look forward to receiving your applications!
If you have any questions regarding the position, you can contact Rustam Galimullin at rustam.galimullin@uib.no
]]>https://su.varbi.com/en/what:job/jobID:947001/where:4/
The thesis work will be conducted within theoretical philosophy. Theoretical philosophy includes epistemology, metaphysics, philosophy of mind, logic, philosophy of language, philosophy of science, as well as the history of philosophy.
2026-10-15
See the job announcement URL above.
]]>Date Monday, 31 August 2026 at 16:00 CEST (UTC+2) on Zoom
Speaker Ian Pratt-Hartmann (Senior Lecturer, University of Manchester and Professor, Uniwersytet Opolski)
Title Variable-ordering fragments of first-order logic
Abstract
In the context of first-order logic, a ‘variable-ordering fragment’ is a subset
of formulas identified by restricting the permitted sequences of variables
appearing as arguments of atomic subformulas. Examples include W.V.O. Quine’s
‘fluted fragment’, A. Herzig’s ‘forward fragment’ and the recently identified
‘adjacent fragment’. All three of these fragments possess the finite model
property and hence are decidable for satisfiability. The largest of these, the
adjacent fragment, extends a wide range of propositional modal logics (under the
standard translation into first-order logic) as well as the two-variable
fragment. In this talk, I shall give an overview of the possible
variable-ordering fragments, and explain how bounds on complexity of
satisfiability can be derived. I shall also survey various extensions of these
logics, in particular with counting quantification.
Date Monday, 22 June 2026 at 16:00 CEST (UTC+2) on Zoom
Speaker Leon Horsten (Professor for Theoretical Philosophy, University of Konstanz)
Title Axioms for Arbitrary Object Theory
Abstract
We formulate and discuss a general axiomatic theory of arbitrary objects. This
theory is expressed in a simple first-order language without modal operators,
and it is governed by classical logic. The theory AOT intends to be a
fundamental and a fully general (and somewhat flexible) theory of arbitrary
objects. Ideally, it intends to be a suitable formal framework for all
legitimate applications of arbitrary object theory. According to the proposed
theory, arbitrary objects are organised in correlated systems, where each such
system of arbitrary objects is abstracted from a system of particular objects.
Date Monday, 25 May 2026 at 15:00 CEST (UTC+2) on Zoom
Speaker Yanjing Wang (Professor of Logic, Peking University)
Title Bundled Fragments of First-order Modal Logic
Abstract
First-order modal logic (FOML) provides a natural logical language for reasoning
about modal attitudes, while retaining the richness of quantification for
referring to predicates over domains. However, FOML is notoriously bad
computationally, as most of the useful fragments of the logic are undecidable,
over many model classes. Over the years, only a few fragments (such as the
monodic fragment) have been shown to be decidable under heavy restrictions on
the syntax. In this talk, I survey our recent work on the newly discovered
bundled fragments based on constructions bundling quantifiers and modalities
together. The idea came from our earlier work on epistemic logics of
know-how/why/what, and it led us to many expressive and decidable fragments of
FOML without restricting the number of variables or the arity of the predicates.
I will give an almost complete picture of the (un)decidability of all the basic
bundled fragments of FOML over increasing and constant domain models. I conclude
with some future directions.
Date Monday, 27 April 2026 at 16:00 CEST (UTC+2) on Zoom
Speaker Ana Ozaki (Associate Professor, University of Oslo)
Title Model Change for Description Logic Concepts
Abstract
The field of Belief Change studies how an agent updates its beliefs in the
presence of new information. In this work, we consider the case where beliefs
are represented as description logic concepts and the new information is in the
format of pointed interpretations. We call this setting model change, and
distinguish three main kinds of changes: eviction, which consists of only
removing models; reception, which incorporates models; and revision, which
combines removal with incorporation of models in a single operation. We
introduce a formal notion of revision and argue that it does not reduce to a
simple combination of eviction and reception, contrary to intuition. We provide
positive and negative results on the compatibility of eviction and reception for
EL and ALC description logic concepts and on the compatibility of revision for
ALC concepts.
In 2026, the Scandinavian Logic Society Symposium (SLSS 2026) and Nordic Logic Summer School (NLSS 2026) organised under the auspices of the Scandinavian Logic Society will take place in Copenhagen!
The primary aim of the Symposium is to promote research in the field of logic (broadly conceived) carried out in research communities in Scandinavia. Moreover, it warmly invites the participation of logicians from all over the world. The meeting will include invited lectures and a forum for participants to present contributed talks.
Call for Abstracts: The scope of SLSS is broad, ranging over the whole areas of Mathematical and Philosophical Logic, as well as Logical Methods in Computer Science, Artificial Intelligence, Linguistics, among others. Major topics include (but are not limited to):
Submissions: Abstracts of contributed talks, in PDF format, not exceeding two A4
(11pt font) pages, should be submitted by 17 May 2026 (AoE) through EasyChair:
https://easychair.org/conferences/?conf=sls2026
Important dates:
Confirmed Invited Speakers:
Programme Committee:
We invite everyone interested in logic and its interface with philosophy, mathematics, computer science, and AI to participate in the Summer School. The intended audience for NLSS is advanced master students, PhD-students, post-docs and experienced researchers wishing to learn the state of the art in a particular subject. As usual, this year we have an exciting lineup of five lecturers on a wide spectrum of topics.
Confirmed NLSS 2026 Lecturers:
Important dates:
Programme Committee:
Both NLSS 2026 and SLSS 2026 are sponsored by the ASL. This means that any
student who wants to attend these events can apply for an ASL Student Travel
Award, to partially cover their expenses. Please note that to do so, the student
must be an ASL member and they must send their application to ASL by May 17th at
the latest. For more information and to apply for an ASL award, please follow
this link:
https://aslonline.org/student-travel-awards/
For more information about the SLSS and NLSS, contact the chair of the local organising committee Nina Gierasimczuk at nigi[at]dtu.dk
]]>Date Monday, 16 March 2026 at 16:00 CET (UTC+1) on Zoom
Speaker Yiannis Moschovakis (Professor of Mathematics Emeritus, University of Athens and UCLA)
Title Intensional semantics for formal and programming languages
Abstract
The claim is that intensions (or meanings) can be modeled usefully by algorithms
which compute truth values, proofs (in various systems), denotations and
implementations of programs (in various programming languages), etc.. I will
discuss the nature of these ‘algorithms’ and present some unpublished results by
me and others on this topic. Most of what I will say is in the book [1] which
contains many unpublished results by Lou van den Dries, Vaughn Pratt, Anush
Tserunyan and others.
[1] Yiannis Moschovakis. Abstract recursion and intrinsic complexity, Cambridge
University Press, Volume 48 in the Lecture Notes in Logic, Association for
Symbolic Logic, 2019. (See
YM’s homepage).