Displaying similar documents to “Submersions and effective descent of étale morphisms”

Morphisms preserving the set of words coding three interval exchange

Tomáš Hejda (2012)

RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications

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Any amicable pair , of Sturmian morphisms enables a construction of a ternary morphism which preserves the set of infinite words coding 3-interval exchange. We determine the number of amicable pairs with the same incidence matrix in SL(2,ℕ) and we study incidence matrices associated with the corresponding ternary morphisms .

Some algorithms to compute the conjugates of Episturmian morphisms

Gwenael Richomme (2010)

RAIRO - Theoretical Informatics and Applications

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Episturmian morphisms generalize Sturmian morphisms. They are defined as compositions of exchange morphisms and two particular morphisms , and . Epistandard morphisms are the morphisms obtained without considering . In [14], a general study of these morphims and of conjugacy of morphisms is given. Here, given a decomposition of an Episturmian morphism over exchange morphisms and , we consider two problems: how to compute a decomposition of one conjugate of ; how to compute...

Finite presentability of strongly finite dilators

Osamu Takaki (2010)

RAIRO - Theoretical Informatics and Applications

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In this paper, we establish the following results: (i) every strongly finite dilator is finitely presentable in the category of endofunctors on the category of ordinals; (ii) a dilator is strongly finite if and only if is finitely presentable in the category of dilators.

Strong functors and interleaving fixpoints in game semantics

Pierre Clairambault (2013)

RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications

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We describe a sequent calculus with primitives for inductive and coinductive datatypes and equip it with reduction rules allowing a sound translation of Gödel’s system T. We introduce the notion of a , relying on a uniform interpretation of open formulas as strong functors. We show that any -closed category is a sound model for . We then turn to the construction of a concrete -closed category based on Hyland-Ong game semantics. The model relies on three main ingredients:...

-Bicomplete Categories and Parity Games

Luigi Santocanale (2010)

RAIRO - Theoretical Informatics and Applications

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For an arbitrary category, we consider the least class of functors containing the projections and closed under finite products, finite coproducts, parameterized initial algebras and parameterized final coalgebras, the class of functors that are definable by -terms. We call the category -bicomplete if every -term defines a functor. We provide concrete examples of such categories and explicitly characterize this class of functors for the category of sets and functions. This goal is achieved...

On the structure of (−)-integers

Wolfgang Steiner (2012)

RAIRO - Theoretical Informatics and Applications

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The (−)-integers are natural generalisations of the -integers, and thus of the integers, for negative real bases. When is the analogue of a Parry number, we describe the structure of the set of (−)-integers by a fixed point of an anti-morphism.

On the structure of (−β)-integers

Wolfgang Steiner (2012)

RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications

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The (−)-integers are natural generalisations of the -integers, and thus of the integers, for negative real bases. When is the analogue of a Parry number, we describe the structure of the set of (−)-integers by a fixed point of an anti-morphism.

Generalizing Substitution

Tarmo Uustalu (2010)

RAIRO - Theoretical Informatics and Applications

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It is well known that, given an endofunctor on a category , the initial -algebras (if existing), , the algebras of (wellfounded) -terms over different variable supplies , give rise to a monad with substitution as the extension operation (the free monad induced by the functor ). Moss [17] and Aczel, Adámek, Milius and Velebil [12] have shown that a similar monad, which even enjoys the additional special property of having iterations for all guarded substitution rules (complete...

Encoding FIX in Object Calculi

Roy L. Crole (2010)

RAIRO - Theoretical Informatics and Applications

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We show that the type theory introduced by Crole and Pitts [3] can be encoded in variants of Abadi and Cardelli's object calculi. More precisely, we show that the type theory presented with judgements of both equality and operational reduction can be translated into object calculi, and the translation proved sound. The translations we give can be seen as using object calculi as a metalanguge within which can be represented; an analogy can be drawn with Martin Löf's Theory of Arities...

Equivalences and Congruences on Infinite Conway Games

Furio Honsell, Marina Lenisa, Rekha Redamalla (2012)

RAIRO - Theoretical Informatics and Applications

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Taking the view that infinite plays are , we study and . These admit a sharp presentation, where non-terminating games are seen as a and game contructors, such as , as . We have shown, in a previous paper, that Conway’s theory of terminating games can be rephrased naturally in terms of game . Namely, various conceptually independent notions of can be defined and shown to coincide on Conway’s terminating games. These are...