Generic Strategies for Chemical Space Exploration

Computational approaches to exploring "chemical universes", i.e., very large sets, potentially infinite sets of compounds that can be constructed by a prescribed collection of reaction mechanisms, in practice suffer from a combinatorial explosion. It quickly becomes impossible to test, for all pairs of compounds in a rapidly growing network, whether they can react with each other. More sophisticated and efficient strategies are therefore required to construct very large chemical reaction networks. Undirected labeled graphs and graph rewriting are natural models of chemical compounds and chemical reactions. Borrowing the idea of partial evaluation from functional programming, we introduce partial applications of rewrite rules. Binding substrate to rules increases the number of rules but drastically prunes the substrate sets to which it might match, resulting in dramatically reduced resource requirements. At the same time, exploration strategies can be guided, e.g. based on restrictions on the product molecules to avoid the explicit enumeration of very unlikely compounds. To this end we introduce here a generic framework for the specification of exploration strategies in graph-rewriting systems. Using key examples of complex chemical networks from sugar chemistry and the realm of metabolic networks we demonstrate the feasibility of a high-level strategy framework. The ideas presented here can not only be used for a strategy-based chemical space exploration that has close correspondence of experimental results, but are much more general. In particular, the framework can be used to emulate higher-level transformation models such as illustrated in a small puzzle game

A bidirectional mapping between English and CNF-based reasoners

If language is a transduction between sound and meaning, the target of semantic interpretation should be the meaning representation expected by general cognition. Automated reasoners provide the best available fully-explicit proxies for general cognition, and they commonly expect Clause Normal Form (CNF) as input. There is a well-known algorithm for converting from unrestricted predicate calculus to CNF, but it is not invertible, leaving us without a means to transduce CNF back to English. I present a solution, with possible repercussions for the overall framework of semantic interpretation

Developmental language disorder and universal grammar

L'étude de la Faculté des langues (FL), telle que définie par la grammaire générative, a été principalement entreprise à travers l'examen des langues adultes, l'acquisition de la langue première, l'acquisition des langues secondes et l'acquisition bilingue. Peu de travaux ont abordé la FL à partir d'une situation d'acquisition atypique, communément appelée Trouble développemental du langage (TDL). Cette thèse est consacrée à l'étude de la façon dont FL est affectée par cette condition malheureuse. Le TDL est manifesté par certains jeunes enfants et adultes et peut être la cause de limitations importantes dans le développement du langage. La production et la compréhension langagières de ce groupe d'enfants sont atypiques par rapport au comportement linguistique d'autres enfants du même âge. Leur atypicité consiste en une grammaire non-cible en ce qui concerne ce qui est autorisé et ce qui est interdit dans la/les langue(s) à laquelle/auxquelles ils sont exposés. Les symptômes les plus communs, d'un point de vue morpho-syntaxique, sont (a) l'omission de morphèmes et de mots, (b) les commissions, c'est-à-dire la présence inadéquate de certains mots ou le remplacement inapproprié de morphèmes et (c) les redoublements, c'est-à-dire, l'apparition de mots ou de morphèmes dans plus de positions que celles autorisées dans la langue cible. Ces symptômes ont été pris comme l’indication que la FL est déficiente. Le résultat de cette défaillance est une grammaire développée par les enfants ayant le TDL qui est qualitativement différente de celle développée par leurs pairs typiques. Cette thèse examinera si la compétence linguistique sous-jacente des enfants DLD est déterminée par les mêmes traits, opérations et principes qui régissent le langage naturel en général. Extraites de la littérature expérimentale sur le TDL, les données pour l’analyse incluent la compréhension et la production par les enfants du TDL et concernent les domaines nominal, temporel/verbal et propositionnel. Les propositionsiii avancées pour rendre compte de ce disorder seront évaluées. Toutes proposent explicitement ou implicitement que la grammaire universelle (GU), c'est-à-dire l'ensemble des traits et opérations phonologiques, sémantiques et syntaxiques qui sous-tendent FL, est défectueuse: certains traits peuvent être absents, ou des opérations peuvent être inactives ou fonctionner par intermittence. Contrairement à ces propositions, l'hypothèse défendue ici est que la GU n'est pas affectée chez les enfants TDL. C'est-à-dire que malgré les nombreuses différences entre le TDL et l'acquisition typique du langage, la GU se révèle être similaire à un certain niveau dans les deux situations d'acquisition. Si la GU était altérée chez les enfants TDL, on s'attendrait à ce que les enfants affectés par cette condition produisent des phrases remarquablement différentes de celles produites par des enfants typiques. Plusieurs études ont révélé que les enfants DLD et leurs pairs typiques peuvent montrer des performances linguistiques similaires en termes de quantité et de type d'erreurs. De plus, les données révèlent que les énoncés TDL ne sont pas toujours erronés; lorsque tous les éléments et les mécanismes linguistiques sont présents, ils sont correctement utilisés. Ceci est considéré comme un signe que les traits syntaxiques, bien qu'ils ne soient pas toujours réalisés morpho-phonologiquement, sont présents dans les dérivations syntaxiques des enfants TDL, et que les opérations syntaxiques Fusion et Accord sont actives, tout comme dans les grammaires typiques. Enfin, l'analyse des énoncés non-cibles par les enfants TDL met en évidence une grammaire syntaxiquement normale et même une ressemblance avec des langues auxquelles ces enfants n'ont pas été exposés. La conclusion est que, malgré la non-convergence entre le TDL et la langue cible, la GU dans cette situation d'acquisition est intacte.The study of the Faculty of Language (FL), as defined by generative grammar, has been mainly undertaken through the examination of adult language, first language acquisition, second language acquisition and bilingual acquisition. Few works have approached the FL from an atypical acquisitional situation, standardly called Developmental Language Disorder (DLD). This dissertation is devoted to the study of how FL is affected by this unfortunate condition. DLD is displayed by some young children and adults and can be the cause of significant limitations in language development. The linguistic production and comprehension by this group of children is atypical compared to the linguistic behaviour of other children of the same age. Their atypicality consists in a non-target-like grammar with regard to both what is allowed and what is disallowed in the language(s) to which they are exposed. The most common symptoms, from a morpho-syntactic point of view, are (a) omission of morphemes and words, (b) commissions, i.e., the inadequate presence of certain words or the inappropriate replacement of morphemes and (c) doublings, i.e., the appearance of words or morphemes in more positions than are allowed in the target language. These symptoms have been taken to indicate that the FL is deficient. The result of this deficiency is a grammar developed by children with DLD that is qualitatively different from that developed by their typical peers. This dissertation will consider whether or not the underlying linguistic competence of children with DLD is determined by the same features, operations and principles that regulate natural language in general. Drawn from the experimental literature on DLD, the data for analysis include comprehension and production by children with DLD and concern the nominal, the temporal/verbal and the propositional domains. The proposals that have been put forth to account for this impairment will be evaluated. All of them explicitly or implicitly propose that Universal Grammar (UG), i.e., the set of phonological, semantic and syntactic features and operations that underlie FL, is faulty: Some features can be absent, or operations can be inactive or function intermittently. Contrary to these proposals, the hypothesis defended here is that UG is not affected in DLD children. That is to say, despite the many differences between DLD and typical language acquisition, UG is revealed to be similar at a certain level in both acquisitional situations. If UG were impaired in DLD, children affected by this condition would be expected to produce sentences remarkably different from those produced by typical children. Several studies have shown that children with DLD and their typical peers can display similar linguistic performance in terms of both quantity and type of errors. Moreover, the data reveal that DLD utterances are not always erroneous; when all linguistic elements and mechanisms are present, they are correctly used. This is taken as a sign that syntactic features, while not always realized morpho-phonologically, are present in DLD syntactic derivations, and that the syntactic operations Merge and Agree are active, just as in typical grammars. Finally, the analysis of non-target utterances by children with DLD evinces a syntactically normal grammar and even a resemblance with languages to which these children have not been exposed. The conclusion is that, despite the non-convergence of DLD and the target language, UG in this acquisitional situation is intact

Abductive speech act recognition, corporate agents and the COSMA system

This chapter presents an overview of the DISCO project\u27s solutions to several problems in natural language pragmatics. Its central focus is on relating utterances to intentions through speech act recognition. Subproblems include the incorporation of linguistic cues into the speech act recognition process, precise and efficient multiagent belief attribution models (Corporate Agents), and speech act representation and processing using Corporate Agents. These ideas are being tested within the COSMA appointment scheduling system, one application of the DISCO natural language interface. Abductive speech act processing in this environment is not far from realizing its potential for fully bidirectional implementation

Toward a Cognitive Classical Linguistics. The Embodied Basis of Constructions in Greek and Latin

The volume that gathers a series of papers bringing together the study of grammatical and syntactic constructions in Greek and Latin under the perspective of theories of embodied meaning developed in cognitive linguistics