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Relation lifting, with an application to the many-valued cover modality

Marta Bilkova ; Alexander Kurz ; Daniela Petrisan ; Jiri Velebil.

We introduce basic notions and results about relation liftings on categories enriched in a commutative quantale. We derive two necessary and sufficient conditions for a 2-functor T to admit a functorial relation lifting: one is the existence of a distributive law of T over the "powerset monad" on&nbsp;[&hellip;]

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Nominal Coalgebraic Data Types with Applications to Lambda Calculus

Alexander Kurz ; Daniela Luan Petrişan ; Paula Severi ; Fer-Jan de Vries.

We investigate final coalgebras in nominal sets. This allows us to define types of infinite data with binding for which all constructions automatically respect alpha equivalence. We give applications to the infinitary lambda calculus.

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Completeness for the coalgebraic cover modality

Clemens Kupke ; Alexander Kurz ; Yde Venema.

We study the finitary version of the coalgebraic logic introduced by L. Moss. The syntax of this logic, which is introduced uniformly with respect to a coalgebraic type functor, required to preserve weak pullbacks, extends that of classical propositional logic with a so-called coalgebraic cover&nbsp;[&hellip;]

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Epistemic Updates on Algebras

Alexander A Kurz ; Alessandra A Palmigiano.

We develop the mathematical theory of epistemic updates with the tools of duality theory. We focus on the Logic of Epistemic Actions and Knowledge (EAK), introduced by Baltag-Moss- Solecki, without the common knowledge operator. We dually characterize the product update construction of EAK as a&nbsp;[&hellip;]

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Strongly Complete Logics for Coalgebras

Alexander Kurz ; Jiri Rosicky.

Coalgebras for a functor model different types of transition systems in a uniform way. This paper focuses on a uniform account of finitary logics for set-based coalgebras. In particular, a general construction of a logic from an arbitrary set-functor is given and proven to be strongly complete under&nbsp;[&hellip;]

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Extending set functors to generalised metric spaces

Adriana Balan ; Alexander Kurz ; Jiří Velebil.

For a commutative quantale $\mathcal{V}$, the category $\mathcal{V}-cat$ can be perceived as a category of generalised metric spaces and non-expanding maps. We show that any type constructor $T$ (formalised as an endofunctor on sets) can be extended in a canonical way to a type constructor&nbsp;[&hellip;]

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