#### Registration is open for NLS, SLSS, and GandALF 2024! Early registration deadline for all: May 31.

# SLSS 2024

Reykjavik Summer of Cool Logic 2024 (SCooL 2024), Reykjavik 10-21/6 2024

## Twelfth Scandinavian Logic Symposium (SLSS 2024)

### 14–16 June 2024, Reykjavík, Iceland

The twelfth Scandinavian Logic Symposium (SLSS 2024) will be held at Reykjavik University, Iceland, during 14-16 June, 2024, under the auspices of the Scandinavian Logic Society. The previous four meetings of the SLSS were held in Bergen in Norway (2022), Gothenburg in Sweden (2018), Tampere in Finland (2014), and Roskilde in Denmark (2012).

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.

**Suggested topics**

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)

- Proof Theory
- Constructivism
- Model Theory
- Set Theory
- Computability Theory
- Algebra and Logic
- Categorical Logic
- Modal and Temporal Logics
- Dynamic Logics
- Logic and Computer Science
- Logic in AI and Multi-Agent Systems
- Logic and Linguistics
- Philosophical Logic
- Philosophy of Logic, Mathematics and Computation

### Programme Committee

**Co-chairs**

Antonios Achilleos (Reykjavik University)

Dag Westerståhl (Stockholm University, Tsinghua University)

**Members**

Gaia Belardinelli (University of Copenhagen)

Jens Classen (Roskilde University)

Salvatore Florio (University of Oslo)

Juha Kontinen (University of Helsinki)

Vera Koponen (Uppsala University)

Magdalena Ortiz (TU Wien)

Mina Young Pedersen (University of Bergen)

Esko Turunen (TU Wien)

### Invited Speakers

Fausto Barbero (University of Helsinki)

Sara Negri (University of Genoa)

Aybüke Özgün (ILLC, University of Amsterdam)

### Submissions

Abstracts of contributed talks, in PDF format, not exceeding two A4 (11pt) pages, should be submitted through EasyChair: https://easychair.org/conferences/?conf=slss2024.

Abstracts should be typeset following the format of a LaTeX class file SLS2014.cls, or in a similar format if you prefer to not use LaTeX.

### Important dates

Submission deadline: ~~7 April~~ 12 April

Notification: 30 April

Early registration deadline: 24 May

Conference: 14-16 June, 2024

### Programme

#### Invited Talk Abstracts

**Fausto Barbero (University of Helsinki)**

*Title:* Causal models and their generalizations

*Abstract:* The Structural Equation models considered in the field of causal inference describe causation in terms of functions that relate the behaviour of different magnitudes (variables). Galles and Pearl (1997) observed that the same framework supports a notion of (interventionist) counterfactual that differs from those offered by the philosophical literature, and to which many notions of causation can be reduced.

I will give an overview of the logic literature on interventionist counterfactuals, starting with the classical results in the context of standard causal models. Next, I will point to some causality-related issues that are not represented in causal models, such as the interaction of observations and interventions, and the possibility of assuming indeterministic causal laws; and make a case that appropriate generalizations of team semantics and possible-world semantics may be good candidates for extending the formalization of causal discourse.

**Sara Negri (University of Genoa)**

*Title:* Second order well-behaved

*Abstract:* Second-order logic extends the expressive power of first-order logic, allowing for the representation of properties that involve quantification over all subsets or families of subsets within a given structure, addressing a fundamental need in mathematical discourse. However, while offering significant advantages, full second-order logic faces challenges due to its impredicative nature and the absence of crucial metalogical properties, which complicates the development of proof systems. Our research tackles these challenges by introducing G3-style sequent calculi that incorporate a predicative comprehension schema, facilitating constructive cut-elimination proofs.

Expanding upon these calculi, we delve into the proof theory of mathematical theories, adapting methods from first-order calculi and establishing structural results for both classical and intuitionistic versions of the calculi. Additionally, we define extensional equality and apartness within second-order logic, demonstrating the ability to reduce mathematical concepts to pure logical terms. To illustrate, we present the theories of von Neumann–G¨odel–Bernays set theory and predicative second-order arithmetic. Moreover, we establish a variant of Herbrand’s theorem tailored for predicative second-order intuitionistic logic, demonstrating the conservativity of predicative second-order Heyting arithmetic over its first-order counterpart. Furthermore, we extend the interpolation theorem and modal embedding of intuitionistic logic to predicative second-order logic.

**Aybüke Özgün (ILLC, University of Amsterdam)**

*Title:* Imagination, Mereotopology, and Topic Expansion

*Abstract:* Intentional modals have recently received topic-sensitive treatment. One application involves the logic of imagination. According to a prominent treatment by Berto (2018, 2022), the topic of the imaginative output must be contained within the topic of the imaginative input. That is, imaginative episodes can never expand what they are about. We argue that this
constraint is implausible from a psychological point of view, and it wrongly predicts the falsehood of true reports of imagination. Thus the constraint should be relaxed; but how? In this work, we explore a number of direct approaches to relaxing the controversial content-inclusion constraint. The core idea is to consider adding an expansion operator to the mereology of topics. The logic that results depends on the formal constraints placed on topic expansion, the choice of which are subject to philosophical dispute. The first semantics we explore is a topological approach using a closure operator. The second approach uses an inclusive and monotone increasing operator, and we give a sound and complete axiomatisation for its logic. The third approach uses an inclusive and additive operator, and we show that the associated logic is strictly weaker than the previous two systems.

Time permitting, I will also elaborate on further generalizations of the topic-sensitive semantics of imagination and the applications of proposed topic expansion operators to knowledge, belief, and conditionals. The main part of this talk is based on joint work with Aaron J. Cotnoir.

### Accepted Papers

### Schedule

Friday | Saturday | Sunday | |
---|---|---|---|

8:30-8:50 | Registration | ||

8:50-9:00 | Welcome - opening | ||

9:00-10:00 Invited talks: |
Aybüke Özgün. Imagination, Mereotopology, and Topic Expansion |
Fausto Barbero. Causal models and their generalizations |
Sara Negri. Second-order well-behaved |

10:00-10:30 | Coffee break | Coffee break | Coffee break |

10:30-11:00 | Alexander Gheorghiu, Tao Gu and David Pym. A Note on an Inferentialist Approach to Resource Semantics |
Micol Pasti. Theory or metatheory? At What Level Should We Be Pluralists About Logic? |
Vít Punčochář. An algebraic representation of information types |

11:00-11:30 | Tianyi Chu. A Logic of Topic-sensitive and Fragmented Hyperintensional Belief |
Pietro Vigiani. Entailment and Containment: a Ternary and Contextual approach to Information and Topic Inclusion |
Kerkko Luosto and Lauri Hella. Variants of the prenex normal form game |

11:30-12:00 | Elio La Rosa. Epsilon Modal Logics |
Giada Coleschi. Gibberish and Ungrammaticality |
Vera Koponen. Random Expansions Of Finite Structures With Bounded Degree |

12:00-13:30 | Lunch | Lunch | Lunch |

13:30-14:00 | Haitian Wang, Malvin Gattinger and Avijeet Gosh. How to represent a Kripke model? From BDDs to Mental Programs |
Bas Kortenbach, Luca Incurvati and Julian Schlöder. Multilateral Supervaluationism and Classicality |
Pawel Pawlowski and Daniel Skurt. Non-deterministic approach to modality |

14:00-14:30 | Stipe Pandžić. Inductive learning with first-order justification logic |
Pedro del Valle-Inclan. Carnap’s Problem, Definability and Compositionality |
Camillo Fiore and Bruno Da Ré. Maximally Substructural Classical Logic |

14:30-15:00 | Coffee break | Sam Sanders and Dag Normann. The Big, Bigger, and Biggest Five of Reverse Mathematics |
Camillo Fiore. Notational Variance in Substructural Logics |

15:00-15:30 | Bartosz Więckowski. Proof-theoretic considerations on the structure of reasoning with counterfactuals and knowledge |
||

15:30-16:00 | Karol Wapniarski. The (Non)emptiness Problem: Ontological Assumptions of Traditional Logic from Aristotle to Gorge Boole |
||

16:00-16:30 | Daniel Leivant. Finitism distilled |

**Room:** M103

The room is on the ground floor (1st floor) of the building. Maps of the building can be found here.

**The NLS and SLSS dinner** takes place on Thursday 13/6 at 7 pm at *La Primavera* restaurant at Harpa.
For directions, see here.