2,663 research outputs found
Building and Combining Matching Algorithms
International audienceThe concept of matching is ubiquitous in declarative programming and in automated reasoning. For instance, it is a key mechanism to run rule-based programs and to simplify clauses generated by theorem provers. A matching problem can be seen as a particular conjunction of equations where each equation has a ground side. We give an overview of techniques that can be applied to build and combine matching algorithms. First, we survey mutation-based techniques as a way to build a generic matching algorithm for a large class of equational theories. Second, combination techniques are introduced to get combined matching algorithms for disjoint unions of theories. Then we show how these combination algorithms can be extended to handle non-disjoint unions of theories sharing only constructors. These extensions are possible if an appropriate notion of normal form is computable
Prolegomena to a neurocomputational architecture for human grammatical encoding and decoding
The study develops a neurocomputational architecture for grammatical processing in language production and language comprehension (grammatical encoding and decoding, respectively). It seeks to answer two questions. First, how is online syntactic structure formation of the complexity required by natural-language grammars possible in a fixed, preexisting neural network without the need for online creation of new connections or associations? Second, is it realistic to assume that the seemingly disparate instantiations of syntactic structure formation in grammatical encoding and grammatical decoding can run on the same neural infrastructure? This issue is prompted by accumulating experimental evidence for the hypothesis that the mechanisms for grammatical decoding overlap with those for grammatical encoding to a considerable extent, thus inviting the hypothesis of a single âgrammatical coder.â The paper answers both questions by providing the blueprint for a syntactic structure formation mechanism that is entirely based on prewired circuitry (except for referential processing, which relies on the rapid learning capacity of the hippocampal complex), and can subserve decoding as well as encoding tasks. The model builds on the âUnification Spaceâ model of syntactic parsing developed by Vosse & Kempen (2000, 2008, 2009). The design includes a neurocomputational mechanism for the treatment of an important class of grammatical movement phenomena
Termination of Narrowing: Automated Proofs and Modularity Properties
En 1936 Alan Turing demostro que el halting problem, esto es, el problema de decidir
si un programa termina o no, es un problema indecidible para la inmensa mayoria de
los lenguajes de programacion. A pesar de ello, la terminacion es un problema tan
relevante que en las ultimas decadas un gran numero de tecnicas han sido desarrolladas
para demostrar la terminacion de forma automatica de la maxima cantidad posible de
programas. Los sistemas de reescritura de terminos proporcionan un marco teorico
abstracto perfecto para el estudio de la terminacion de programas. En este marco, la
evaluaci on de un t ermino consiste en la aplicacion no determinista de un conjunto de
reglas de reescritura.
El estrechamiento (narrowing) de terminos es una generalizacion de la reescritura
que proporciona un mecanismo de razonamiento automatico. Por ejemplo, dado un
conjunto de reglas que denan la suma y la multiplicacion, la reescritura permite calcular
expresiones aritmeticas, mientras que el estrechamiento permite resolver ecuaciones
con variables. Esta tesis constituye el primer estudio en profundidad de las
propiedades de terminacion del estrechamiento. Las contribuciones son las siguientes.
En primer lugar, se identican clases de sistemas en las que el estrechamiento tiene
un comportamiento bueno, en el sentido de que siempre termina. Muchos metodos
de razonamiento automatico, como el analisis de la semantica de lenguajes de programaci
on mediante operadores de punto jo, se benefician de esta caracterizacion.
En segundo lugar, se introduce un metodo automatico, basado en el marco teorico
de pares de dependencia, para demostrar la terminacion del estrechamiento en un
sistema particular. Nuestro metodo es, por primera vez, aplicable a cualquier clase
de sistemas.
En tercer lugar, se propone un nuevo metodo para estudiar la terminacion del
estrechamiento desde un termino particular, permitiendo el analisis de la terminacion
de lenguajes de programacion. El nuevo metodo generaliza losIborra LĂłpez, J. (2010). Termination of Narrowing: Automated Proofs and Modularity Properties [Tesis doctoral no publicada]. Universitat PolitĂšcnica de ValĂšncia. https://doi.org/10.4995/Thesis/10251/19251Palanci
Rule-Based Unification in Combined Theories and the Finite Variant Property
International audienceWe investigate the unification problemin theories defined by rewrite systems which are both convergent andforward-closed. These theories are also known in the context ofprotocol analysis as theories with the finite variant property andadmit a variant-based unification algorithm. In this paper, wepresent a new rule-based unification algorithm which can be seen as analternative to the variant-based approach. In addition, we defineforward-closed combination to capture the union of a forward-closedconvergent rewrite system with another theory, such as theAssociativity-Commutativity, whose function symbols may occur inright-hand sides of the rewrite system. Finally, we present acombination algorithm for this particular class of non-disjoint unionsof theories
Approximate text generation from non-hierarchical representations in a declarative framework
This thesis is on Natural Language Generation. It describes a linguistic realisation
system that translates the semantic information encoded in a conceptual graph into an
English language sentence. The use of a non-hierarchically structured semantic representation (conceptual graphs) and an approximate matching between semantic structures allows us to investigate a more general version of the sentence generation problem
where one is not pre-committed to a choice of the syntactically prominent elements in
the initial semantics. We show clearly how the semantic structure is declaratively related to linguistically motivated syntactic representation â we use D-Tree Grammars
which stem from work on Tree-Adjoining Grammars. The declarative specification of
the mapping between semantics and syntax allows for different processing strategies
to be exploited. A number of generation strategies have been considered: a pure topdown strategy and a chart-based generation technique which allows partially successful
computations to be reused in other branches of the search space. Having a generator
with increased paraphrasing power as a consequence of using non-hierarchical input
and approximate matching raises the issue whether certain 'better' paraphrases can be
generated before others. We investigate preference-based processing in the context of
generation
Unification dans des mélanges non-disjoints avec des théories fermées en avant
We investigate the unification problemin theories defined by rewrite systems which are both convergent andforward-closed. These theories are also known in the context ofprotocol analysis as theories with the finite variant property andadmit a variant-based unification algorithm. In this paper, wepresent a new rule-based unification algorithm which can be seen as analternative to the variant-based approach. In addition, we defineforward-closed combination to capture the union of a forward-closedconvergent rewrite system with another theory, such as theAssociativity-Commutativity, whose function symbols may occur inright-hand sides of the rewrite system. Finally, we present acombination algorithm for this particular class of non-disjoint unionsof theories.On Ă©tudie le problĂšme dâunification dans les thĂ©ories dĂ©finies par des systĂšmes derĂ©Ă©criture qui sont Ă la fois convergents et fermĂ©s en avant. Ces thĂ©ories sont connues dans lecontexte de lâanalyse de protocoles de sĂ©curitĂ© comme les thĂ©ories ayant la propriĂ©tĂ© des variantsfinis et admettant de ce fait un algorithme dâunification Ă base de variants. Dans ce papier,on prĂ©sente un nouvel algorithme dâunification Ă base de rĂšgles qui peut ĂȘtre vu comme unealternative Ă lâapproche basĂ©e sur le calcul de variants. On Ă©tudie lâunion dâun systĂšme derĂ©Ă©criture convergent et fermĂ© en avant avec une autre thĂ©orie dont les symboles de fonctionpeuvent apparaĂźtre dans les membres droits du systĂšme de rĂ©Ă©criture. Finalement, on prĂ©senteun algorithme de combinaison pour cette classe particuliĂšre dâunions non-disjointes de thĂ©ories
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