Results 1  10
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14
Strongly complete logics for coalgebras
, 2006
"... Coalgebras for a functor T on a category X model many different types of transition systems in a uniform way. This paper focuses on a uniform account of finitary strongly complete specification languages for Setbased coalgebras. We show how to associate a finitary logic to any finitesets preservin ..."
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Cited by 11 (4 self)
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Coalgebras for a functor T on a category X model many different types of transition systems in a uniform way. This paper focuses on a uniform account of finitary strongly complete specification languages for Setbased coalgebras. We show how to associate a finitary logic to any finitesets preserving functor T and prove the logic to be strongly complete under a mild condition on T. The proof is based on the following result. An endofunctor on a variety has a presentation by operations and equations iff it preserves sifted colimits. 1
Notions of Lawvere theory
"... Categorical universal algebra can be developed either using Lawvere theories (singlesorted finite product theories) or using monads, and the category of Lawvere theories is equivalent to the category of finitary monads on Set. We show how this equivalence, and the basic results of ..."
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Cited by 10 (0 self)
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Categorical universal algebra can be developed either using Lawvere theories (singlesorted finite product theories) or using monads, and the category of Lawvere theories is equivalent to the category of finitary monads on Set. We show how this equivalence, and the basic results of
Functorial coalgebraic logic: The case of manysorted varieties
 Electron. Notes Theor. Comput. Sci
"... Following earlier work, a modal logic for Tcoalgebras is a functor L on a suitable variety. Syntax and proof system of the logic are given by presentations of the functor. This paper makes two contributions. First, a previous result characterizing those functors that have presentations is generaliz ..."
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Cited by 5 (4 self)
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Following earlier work, a modal logic for Tcoalgebras is a functor L on a suitable variety. Syntax and proof system of the logic are given by presentations of the functor. This paper makes two contributions. First, a previous result characterizing those functors that have presentations is generalized from endofunctors on onesorted varieties to functors between manysorted varieties. This yields an equational logic for the presheaf semantics of higherorder abstract syntax. As another application, we show how the move to functors between manysorted varieties allows to modularly combine syntax and proof systems of different logics. Second, we show how to associate to any setfunctor T a complete (finitary) logic L consisting of modal operators and Boolean connectives.
On coalgebras over algebras
 In ”Proceedings of the Tenth Workshop on Coalgebraic Methods in Computer Science (CMCS 2010)”, Electr. Notes
"... We extend Barr’s wellknown characterization of the final coalgebra of a Setendofunctor H as the completion of its initial algebra to the EilenbergMoore category Alg(M) of algebras associated to a Setmonad M, if H can be lifted to Alg(M). As further analysis, we introduce the notion of commuting ..."
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Cited by 4 (0 self)
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We extend Barr’s wellknown characterization of the final coalgebra of a Setendofunctor H as the completion of its initial algebra to the EilenbergMoore category Alg(M) of algebras associated to a Setmonad M, if H can be lifted to Alg(M). As further analysis, we introduce the notion of commuting pair of endofunctors (T,H) with respect to a monad M and show that under reasonable assumptions, the final Hcoalgebra can be obtained as the completion of the free Malgebra on the initial Talgebra.
Instances of computational effects: an algebraic perspective
"... Abstract—We investigate the connections between computational effects, algebraic theories, and monads on functor categories. We develop a syntactic framework with variable binding that allows us to describe equations between programs while taking into account the idea that there may be different ins ..."
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Abstract—We investigate the connections between computational effects, algebraic theories, and monads on functor categories. We develop a syntactic framework with variable binding that allows us to describe equations between programs while taking into account the idea that there may be different instances of a particular computational effect. We use our framework to give a general account of several notions of computation that had previously been analyzed in terms of monads on presheaf categories: the analysis of local store by Plotkin and Power; the analysis of restriction by Pitts; and the analysis of the pi calculus by Stark. I.
Note on the construction of free monoids
, 2008
"... We construct free monoids in a monoidal category (C, ⊗, I) with finite limits and countable colimits, in which tensoring on either side preserves reflexive coequalizers and colimits of countable chains. ..."
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We construct free monoids in a monoidal category (C, ⊗, I) with finite limits and countable colimits, in which tensoring on either side preserves reflexive coequalizers and colimits of countable chains.
Accessible categories and homotopy theory
, 2007
"... Accessible categories have recently turned out to be useful in homotopy theory. This text is prepared as notes for a series of lectures at ..."
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Accessible categories have recently turned out to be useful in homotopy theory. This text is prepared as notes for a series of lectures at
Freyd categories are enriched Lawvere theories
"... Abstract Lawvere theories provide a categorical formulation of the algebraic theories from universal algebra. Freyd categories are categorical models of firstorder effectful programming languages. The notion of sound limit doctrine has been used to classify accessible categories. We provide a defi ..."
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Abstract Lawvere theories provide a categorical formulation of the algebraic theories from universal algebra. Freyd categories are categorical models of firstorder effectful programming languages. The notion of sound limit doctrine has been used to classify accessible categories. We provide a definition of Lawvere theory that is enriched in a closed category that is locally presentable with respect to a sound limit doctrine. For the doctrine of finite limits, we recover Power's enriched Lawvere theories. For the empty limit doctrine, our Lawvere theories are Freyd categories, and for the doctrine of finite products, our Lawvere theories are distributive Freyd categories. In this sense, computational effects are algebraic.
An algebraic presentation of predicate logic (extended abstract)
"... Abstract. We present an algebraic theory for a fragment of predicate logic. The fragment has disjunction, existential quantification and equality. It is not an algebraic theory in the classical sense, but rather within a new framework that we call ‘parameterized algebraic theories’. We demonstrate t ..."
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Abstract. We present an algebraic theory for a fragment of predicate logic. The fragment has disjunction, existential quantification and equality. It is not an algebraic theory in the classical sense, but rather within a new framework that we call ‘parameterized algebraic theories’. We demonstrate the relevance of this algebraic presentation to computer science by identifying a programming language in which every type carries a model of the algebraic theory. The result is a simple functional logic programming language. We provide a syntaxfree representation theorem which places terms in bijection with sieves, a concept from category theory. We study presentationinvariance for general parameterized algebraic theories by providing a theory of clones. We show that parameterized algebraic theories characterize a class of enriched monads. 1