Craig interpolation is the property held of many logics that for any valid implication A -> B there exists a formula I using only vocabulary common to both A and B such that A -> I and I -> B are both valid. The property is named after William Craig who formulated and proved the result for classical first-order logic in 1957.

Proof-theoretic treatments of interpolation, by their nature, offer further insights into a logic, such as characterising the complexity of interpolants. I will showcase several remarkable consequences of interpolation in the context of modal logic with fixed points, ranging from characterisatisons of expressivity using fixed points to the solution of certain decidability problems.

The 13th Scandinavian Logic Society Symposium (SLSS 2026) and 6th Nordic Logic Summer School (NLSS 2026) take place this year in Copenhagen under the auspices of the Scandinavian Logic Society on the dates

• Nordic Logic Summer School: 17–20 August, 2026
• Scandinavian Logic Society Symposium: 21–23 August, 2026

The Call for Papers is reproduced below; see the conference website for further details and updates.

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13th Scandinavian Logic Symposium (SLSS 2026)

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.

Important dates:

• Abstract submission deadline: 17 May 2026
• Notification of acceptance: 9 June 2026
• Early registration deadline: 15 June 2026
• SLSS 2026: 21–23 August 2026

Confirmed Invited Speakers:

• Salvatore Florio (Oslo, Norway)
• Vera Koponen (Uppsala, Sweden)
• Magdalena Ortiz (TU Wien, Austria)
• Carsten Schürmann (ITU, Denmark)

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):

• 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 and Learning
• Logic in AI and Multi-Agent Systems
• Logic and Linguistics
• Philosophical Logic
• Philosophy of Logic, Mathematics and Computation

Submissions

Abstracts of contributed talks, in PDF format, not exceeding two A4 (11pt font) pages, should be submitted through EasyChair: https://easychair.org/conferences/?conf=sls2026 by 17 May 2026 (AoE).

Programme Committee

• Thomas Bolander, Technical University of Denmark
• Aggeliki Chalki, Reykjavik University
• Laura Crosilla, University of Florence
• Nina Gierasimczuk, Technical University of Denmark
• Juha Kontinen (co-chair), University of Helsinki
• Antti Kuusisto, Tampere University
• Peter LeFanu Lumsdaine, Stockholm University
• Graham Leigh (co-chair), University of Gothenburg
• Ana Ozaki, University of Oslo
• Niccolò Veltri, Tallinn University of Technology
• Thomas Ågotnes, University of Bergen

6th Nordic Logic Summer School (NLSS 2026)

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:

• Bahareh Afshari (University of Gothenburg, Sweden)
• Patrik Blackburn (Roskilde University, Denmark)
• Gaia Belardinelli (Stanford University, USA)
• Balder ten Cate (University of Amsterdam, The Netherlands)
• and one more TBA

Important dates:

• Early registration deadline: 1 July 2026
• NLSS 2026: 17–20 August 2026

Programme Committee:

• Ali Enayat, University of Gothenburg
• Thomas Bolander (co-chair), Technical University of Denmark
• Øystein Linnebo (co-chair), University of Oslo
• Sara Negri, University of Genoa
• Sonja Smets, University of Amsterdam

Sponsorship by the Association for Symbolic Logic

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/

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For more information about the SLSS and NLSS, contact the chair of the local organising committee Nina Gierasimczuk at nigi[at]dtu.dk