Algebra|Coalgebra Seminar

[News & Future Meetings]  [Previous Meetings]   [Contact]  

This page concerns the Algebra|Coalgebra Seminar at the Institute for Logic, Language & Computation (ILLC) of the University of Amsterdam. The purpose of the seminar is to disseminate results and insights about and around algebraic and coalgebraic methods in logic.

News & Future meetings

    Speaker: Graham Leigh (University of Gothenburg)

    Title: Cyclic proofs for circular reasoning

    Coordinates: Wednesday, 27 March 2019, from 16:00 to 17:00 in room F1.15, Science Park 107, Amsterdam.


    Modal logic is an efficient and effective language for state-based reasoning. Its versatility is witnessed in its robustness when extended by non-local modalities: common knowledge, temporal modalities, computationally motivated `path quantifiers' and dynamic modalities, and even provability. These are all examples of modalities expressing infinitary properties of state systems: reachability or closure under fixpoint semantics. Logics built over these fixpoint modalities have natural semantics but provide a clear challenge to the development of sound and complete proof systems. In this talk, I will overview the proof theory of these expressive modal logics with a focus on re-interpreting the notion of proof in view of semantic considerations.


    Speaker: Sebastian Enqvist (Stockholm University)

    Title: Flat fixpoint logics with converse modalities

    Coordinates: Wednesday, 3 April 2019, from 14:00 to 15:00 in room F1.15, Science Park 107, Amsterdam.

Previous Meetings

  • Title: Trajectory domains: analyzing the behavior of transition systems
    Speaker: Levin Hornischer (ILLC)
    Date: Wednesday, 13 March, 2019.

  • Title: Coalgebra Learning via Duality
    Speaker: Clemens Kupke (University of Strathclyde)
    Date: Wednesday, 27 February, 2019.

  • Title: Modal logics of polygons and beyondy
    Speaker: David Gabelaia (Tbilisi State University, A. Razmadze Mathematical Institute)
    Date: Wednesday, 30 January, 2019.

  • Title: Logical aspects of algebra-valued models of set theory
    Speaker: Robert Paßmann (ILLC)
    Date: Wednesday, 19 December, 2018.

  • Title: Automata that Transform Infinite Words
    Speaker: Jörg Endrullis (Vrije Universiteit Amsterdam)
    Date: Wednesday, 5 December, 2018.

  • Title: Beth definability and the Stone-Weierstrass Theorem
    Speaker: Luca Reggio (Czech Academy of Sciences)
    Date: Wednesday, 28 November, 2018.

  • Title: What is the size of a formula? Basic size matters in the modal mu-calculus
    Speaker: Yde Venema (ILLC)
    Date: Wednesday, 21 November, 2018.

  • Title: Etale groupoid convolution algebras
    Speaker: Benjamin Steinberg (CUNY)
    Date: Wednesday, 7 November, 2018.

  • Title: Difference hierarchies and duality
    Speaker: Célia Borlido (Laboratoire J.A. Dieudonné)
    Date: Wednesday, 31 October, 2018.

  • Title: Point-free geometries - foundations and systems
    Speaker: Rafał Gruszczyński (Nicolaus Copernicus University)
    Date: Wednesday, 10 October, 2018.

  • Title: Hyper-MacNeille completions of Heyting algebras
    Speaker: Frederik M. Lauridsen (ILLC)
    Date: Wednesday, 26 September, 2018.

  • Title: A perspective on non-commutative frame theory
    Speaker: Ganna Kudryavtseva (University of Ljubljana)
    Date: Wednesday, 12 September, 2018.

  • Title: How to extend de Vries duality to completely regular spaces
    Speaker: Guram Bezhanishvili (New Mexico State University)
    Date: Wednesday, 20 June, 2018.

  • Title: Fine-Grained Computational Complexity
    Speaker: Jouke Witteveen (ILLC)
    Date: Wednesday, 6 June, 2018.

  • Title: W Types with Reductions
    Speaker: Andrew Swan (ILLC)
    Date: Wednesday, 23 May, 2018.

  • Title: A simple propositional calculus for compact Hausdorff spaces
    Speaker: Nick Bezhanishvili (ILLC)
    Date: Wednesday, 9 May, 2018.

  • Title: Uniform interpolation via an open mapping theorem for Esakia spaces
    Speaker: Sam van Gool (ILLC)
    Date: Wednesday, 25 April, 2018.

  • Title: Classical equivalents of intuitionistic implication
    Speakers: Esther Boerboom and Noor Heerkens (ILLC)
    Date: Wednesday, 11 April, 2018.

  • Title: Long-Term Values in Markov Decision Processes, (Co)Algebraically
    Speaker: Frank Feys (TU Delft)
    Date: Wednesday, 28 March, 2018.

  • Title: MacNeille transferability
    Speaker: Frederik M. Lauridsen (ILLC)
    Date: Wednesday, 21 March, 2018.

  • Title: Path categories
    Speaker: Benno van den Berg (ILLC)
    Date: Wednesday, 7 March, 2018.

  • Title: Duality in Logic and Computer Science
    Speakers: Thijs Benjamins, Chase Ford, Kristoffer Kalavainen, Kyah Smaal, and Tatevik Yolyan (ILLC)
    Date: Wednesday, 31 January, 2018.

  • Title: Stone-Priestley duality for MTL triples
    Speaker: Wesley Fussner (University of Denver)
    Date: Wednesday, 13 December, 2017.

  • Title: Choice-free Stone duality
    Speaker: Nick Bezhanishvili (ILLC)
    Date: Wednesday, 17 April, 2017.

  • Title: Ordering Free Groups
    Speaker: George Metcalfe (Universität Bern)
    Date: Wednesday, 26 April, 2017.

  • Title: Modal logics of the real line
    Speaker: Andrey Kudinov (HSE Moscow)
    Date: Wednesday, 14 December, 2016.

  • Title: Nominal Sets in Constructive Set Theorys
    Speaker: Andrew Swan (ILLC)
    Date: Wednesday, 9 November, 2016.

  • Title: Some model theory for the modal μ-calculus
    Speaker: Yde Venema (ILLC)
    Date: Wednesday, 26 October, 2016.

  • Title: On generalized Van-Benthem-type characterizations
    Speaker: Grigory Olkhovikov (Ruhr-Universitaet Bochum, Institut fuer Philosophie II)
    Date: Wednesday, 28 September, 2016.

  • Title: Bitopology and four-valued logic
    Speaker: Tomáš Jakl (Charles University, Prague and University of Birmingham)
    Date: Wednesday, 4 May, 2016.

  • Title: MV-algebras and the Pierce-Birkhoff conjecture
    Speaker: Serafina Lapenta (University of Salerno)
    Date: Wednesday, 20 April, 2016.

  • Title: Studying profinite semigroups via logic
    Speaker: Sam van Gool (CUNY City College and ILLC)
    Date: Wednesday, 30 March, 2016.

  • Title: Investigations on Gödel’s incompleteness properties for guarded fragment and other decidable versions of FOL
    Speaker: Mohamed Khaled (Central European University, Budapest)
    Date: Wednesday, 16 March, 2016.

  • Title: Subminimal Logics of Negation
    Speaker: Almudena Colacito (ILLC)
    Date: Wednesday, 9 March, 2016.

  • Title: Weak Subintuitionistic Logic
    Speaker: Fatemeh Shirmohammadzadeh Maleki (Shahid Beheshti University, Tehran and ILLC)
    Date: Wednesday, 24 February, 2016.

  • Title: Monadic second order logic as the model companion of temporal logic
    Speaker: Silvio Ghilardi (University of Milan)
    Date: Wednesday, 27 January, 2016.

  • Title: Duality for Non-monotonic Consequence Relations and Antimatroids
    Speakers: Joahnnes Marti and Riccardo Pinosio (ILLC)
    Date: Wednesday, 2 December, 2015.

  • Title: Some open problems concerning MSO for coalgebras
    Speaker: Sebastian Enqvist (ILLC)
    Date: Wednesday, 18 November, 2015.

  • Title: Derivative and counting operators on topological spaces
    Speaker: Alberto Gatto (Imperial College London)
    Date: Wednesday, 18 November, 2015.

  • Title: Coalgebraic many-valued logics
    Speaker: Marta Bílková (Charles University in Prague)
    Date: Wednesday, 4 November, 2015.

  • Title: The Wellfounded Parts of Final Coalgebras are Initial Algebras
    Speaker: Larry Moss (Indiana University Logic Program and Math department)
    Date: Wednesday, 8 July, 2015.

  • Title: Stable canonical rules: bounded proofs, dichotomy property and admissible bases
    Speaker: Silvio Ghilardi (University of Milan)
    Date: Wednesday, 27 May, 2015.

  • Title: Stone duality above dimension zero
    Speaker: Vincenzo Marra (University of Milan)
    Date: Wednesday, 27 April, 2015.

  • Title: Modal logic of topology
    Speaker: Nick Bezhanishvili (ILLC) and Jan van Mill (KdVI)
    Date: Wednesday, 15 April, 2015.

  • Title: Global caching for the alternation-free coalgebraic mu-calculus
    Speaker: Daniel Hausmann (Friedrich-Alexander University of Erlangen and Nurnberg)
    Date: Wednesday, 1 April, 2015.

  • Title: Dependency as question entailment
    Speaker: Ivano Ciardelli (ILLC, University of Amsterdam)
    Date: Wednesday, 18 March, 2015.

  • Title: Up-to techniques for bisimulations with silent moves
    Speaker: Daniela Petrişan (Raboud University, Nijmegen)
    Date: Wednesday, 4 March, 2015.

  • Title: Strong Completeness for Iteration-free Coalgebraic Dynamic Logics.
    Speaker: Helle Hansen (TU Delft)
    Date: Wednesday, 18 February, 2015.

  • Title: Residuated Basic Algebras
    Speaker: Minghui Ma (Southwest University)
    Date: Wednesday, 4 February, 2015.

  • Title: Non-self-referential realizable frangments of modal and intuitionistic logics
    Speaker: Junhua Yu (Tsinghua University)
    Date: Wednesday, 21 January, 2015.

  • Title: Modal Logics for Presheaf Categories
    Speaker: Giovanni Cina (ILLC, University of Amsterdam)
    Date: Wednesday, 3 December, 2014.

  • Title: Completeness and Incompleteness in Nominal Kleene Algebra
    Speaker: Dexter Kozen (Cornell University)
    Date: Wednesday, 26 November, 2014.

  • Title: Polyhedra: from geometry to logic
    Speaker: Andrea Pedrini (University of Milan)
    Date: Wednesday, 5 November, 2014.

  • Title: Exact Unification Type and Admissible rules
    Speaker: Leonardo Cabrer (University of Florence, Italy)
    Date: Wednesday, 29 October, 2014.

  • Title: PDL has Craig Interpolation since 1981
    Speaker: Malvin Gattinger (ILLC, University of Amsterdam)
    Date: Wednesday, 1 October, 2014.

  • Title: Changing a Semantics: Opportunism, or Courage?
    Speaker: Johan van Benthem (ILLC, University of Amsterdam)
    Date: Wednesday, 17 September, 2014.

  • Title: Axiomatizations of intermediate logics via the pseudo-complemented lattice reduct of Heyting algebras
    Speaker: Julia Ilin (ILLC, University of Amsterdam)
    Date: Wednesday, 11 June, 2014.

  • Title: Duality and canonicity for Boolean algebra with a relation
    Speaker: Sumit Sourabh (ILLC, University of Amsterdam)
    Date: Wednesday, 11 June, 2014.

  • Title: Adding the Supremum to Interpretability Logic
    Speaker: Paula Henk (ILLC, University of Amsterdam)
    Date: Wednesday, 28 May, 2014.

  • Title: Duality for Logic of Quantum Actions
    Speaker: Shengyang Zhong (ILLC, University of Amsterdam)
    Date: Wednesday, 28 May, 2014.

  • Title: Many-valued modal logic over residuated lattices via duality (joint work with Andrew Craig - University of Johannesburg)
    Speaker: Umberto Rivieccio (Delft University of Technology)
    Date: Wednesday, 14 May, 2014.

  • Title: Using Admissible Rules to Characterise Logics
    Speaker: Jeroen Goudsmit (Utrecht University)
    Date: Wednesday, 30 April, 2014.

  • Title: Uniform Interpolation for Coalgebraic Fixpoint Logic
    Speaker: Fatemeh Seifan (ILLC, University of Amsterdam)
    Date: Wednesday, 30 April, 2014.

  • Title: Free algebras for Gödel-Löb provability logic
    Speaker: Sam van Gool (LIAFA, Université Paris-Diderot & Radboud Universiteit Nijmegen)
    Date: Wednesday, 16 April, 2014.

  • Title: Canonical rules for modal logic
    Speaker: Nick Bezhanishvili (ILLC, University of Amsterdam)
    Date: Thursday, 20 March, 2014.

  • Title: From free algebras to proof bounds.
    Speaker: Silvio Ghilardi (University of Milano)
    Date: Thursday, 20 February, 2014.

  • Title: Cut-elimination in circular proofs.
    Speaker: Jérôme Fortier (UQAM / AMU)
    Date: Thursday, 20 February, 2014.

  • Title: Open maps, small maps and final coalgebras.
    Speaker: Benno van den Berg (ILLC, University of Amsterdam)
    Date: Thursday, 6 February, 2014.

  • Title: A coalgebraic view of characteristic formulas in equational modal fixed point logics.
    Speaker: Sebastian Enqvist (ILLC, University of Amsterdam)
    Date: Wednesday, 22 January, 2014.

  • Title: Coalgebriac Announcement Logics
    Speaker: Facundo Carreiro (ILLC, University of Amsterdam)
    Date: Wednesday, 4 December, 2013.

  • Title: An algebraic approach to cut-elimination for substructural logics.
    Speaker: Sumit Sourabh (ILLC, University of Amsterdam)
    Date: Wednesday, 20 November, 2013.

  • Title: Terminal Sequences and Their Coalgebras.
    Speaker: Johannes Marti (ILLC, University of Amsterdam)
    Date: Wednesday, 31 October, 2013.

  • Title: Two isomorphism criteria for directed colimits.
    Speaker: Luca Spada (ILLC, Amsterdam and University of Salerno)
    Date: Wednesday, 9 October, 2013.

  • Title: A non-commutative Priestly duality
    Speaker: Sam van Gool (Radbound University, Nijmegen)
    Date: Wednesday February 13, 2013

  • Title: Bilattices with modal operators
    Speaker: Speaker: Umberto Rivieccio (University of Birmingham)
    Date: Wednesday May 30, 2012

  • Title: Topological- and Neighborhood-Sheaf Semantics for First-Order Modal Logic
    Speaker: Kohei Kishida (ILLC, Amsterdam)
    Date: Wednesday May 23, 2012

    A|C seminar in 2009/2010
    A|C seminar in 2008/2009
    A|C seminar in 2007/2008
    A|C seminar in 2006/2007

  • Contact

    The seminar is currently organized by Bahareh Afshari, Nick Bezhanishvili, and Frederik Lauridsen. If you're interested in giving a talk at the seminar or have any questions regarding the seminar please contact Frederik at f.m.lauridsen[at]

    If you want to subscribe to the A|C seminar mailing list please send an email to Frederik at f.m.lauridsen[at] with the subject "A|C seminar". In case you no longer wish to subscribe to the mailing list send an email to Frederik with the subject "A|C seminar unsubscribe".

    [Privacy Policy]