I am a postdoc at the ILLC in Amsterdam working with Yde Venema on proof systems for modal fixpoint logics.

Before, I did postdocs with Carsten Lutz in the Theory of Artificial Intelligence group at the University of Bremen and with Clemens Kupke in the MSP group at the University of Strathclyde in Glasgow.

I completed my dissertation under the supervision Martin Stokhof and Frank Veltman also at the ILLC. My PhD thesis is on representation theorems for possible world models of belief and meaning with respect to linguistic behavior.

On fixpoint logic:

- A Focus System for the Alternation-Free mu-Calculus
(preprint),

with Y. Venema, accepted to TABLEAUX 2021. - Focus-Style Proof Systems and Interpolation for the
Alternation-Free mu-Calculus (arXiv),

with Y. Venema. - On the Size of Disjunctive Formulas in the
mu-Calculus (arXiv),

with C. Kupke and Y. Venema, at GandALF 2021. - Size Matters in the Modal mu-Calculus (arXiv),

with C. Kupke and Y. Venema. - Completeness for Game Logic (preprint),

with S. Enqvist, H. H. Hansen, C. Kupke and Y. Venema, at LICS 2019. - Parity Games and Automata for Game Logic (preprint,
doi),

with H. H. Hansen, C. Kupke and Y. Venema, at DALI 2017.

This extended version includes all the proofs.

On coalgebraic modal logic, partially based on my MSc thesis:

- Uniform Interpolation for Coalgebraic Fixpoint Logic
(preprint,
doi),

with F. Seifan and Y. Venema, at CALCO 2015. - Lax Extensions of Coalgebra Functors and Their Logic
(preprint,
doi),

with Y. Venema, in the*Journal of Computer and System Sciences*, 2015.

This paper is an extended version of the earlier: - Lax Extensions of Coalgebra Functors (preprint,
doi),

with Y. Venema, at CMCS 2012.

On description logic:

- A Journey into Ontology Approximation: From Non-Horn to
Horn (arXiv,
doi),

with A. Haga, C. Lutz and F. Wolter, at IJCAI 2020. - Query Expressibility and Verification in Ontology-Based
Data Access (arXiv, publisher,
erratum),

with C. Lutz and L. Sabellek, at KR 2018.

On nonmonotonic and conditional logic:

- Conditional Logic is Complete for Convexity in the Plane
(arXiv, doi)

in*The Review of Symbolic Logic*, 2021. - A Discrete Duality Between Nonmonotonic Consequence
Relations and Convex Geometries (preprint,
doi),

with R. Pinosio, in*Order*, 2020. - A Game Semantics for System P (preprint,
doi),

with R. Pinosio, in*Studia Logica*, 2016.

This extended version of the paper contains additional proofs. - Similarity Orders from Causal Equations (preprint,
doi),

with R. Pinosio, at JELIA 2014. - Topological Semantics for Conditionals (preprint),

with R. Pinosio, at LOGICA 2013.

On epistemic game theory:

- Choice Structures in Games (draft),

with P. Galeazzi.

2021 | |

07 Sep | A focus system for the alternation-free mu-calculus, TABLEAUX 2021, online. |

2020 | |

26 Aug | Conditional logic is complete for convexity in the plane, Advances in Modal Logic 2020, online. |

01 Apr | Unification in coalgebraic modal logics, Algebra|Coalgebra Seminar, ILLC, University of Amsterdam. |

20 Feb | Unification in coalgebraic modal logics, Bern Logic Seminar, University of Bern. |

**E-mail:** johannes.marti@gmail.com

**Phone:** +31 20 525 7173

**Mailing Address:**

FNWI, ILLC

Universiteit van Amsterdam

P.O. Box 94242

1090 GE Amsterdam

**Visiting Address:**

Room F2.16

Science Park 107

1098 XG Amsterdam