A Chart-Parsing Algorithm for Efficient Semantic Analysis

In some contexts, well-formed natural language cannot be expected as input to information or communication systems. In these contexts, the use of grammar-independent input (sequences of uninflected semantic units like e.g. language-independent icons) can be an answer to the users' needs. A semantic analysis can be performed, based on lexical semantic knowledge: it is equivalent to a dependency analysis with no syntactic or morphological clues. However, this requires that an intelligent system should be able to interpret this input with reasonable accuracy and in reasonable time. Here we propose a method allowing a purely semantic-based analysis of sequences of semantic units. It uses an algorithm inspired by the idea of ``chart parsing'' known in Natural Language Processing, which stores intermediate parsing results in order to bring the calculation time down. In comparison with using declarative logic programming - where the calculation time, left to a prolog engine, is hyperexponential -, this method brings the calculation time down to a polynomial time, where the order depends on the valency of the predicates.Comment: 7 pages, 1 figure, LaTeX 2e using COLACL and EPSF packages. Proceedings of the 19th International Conference on Computational Linguistics (COLING 2002), Taipei, Republic of China (Taiwan), 24 Aug. - 1 Sept. 200

A Layered Grammar Model: Using Tree-Adjoining Grammars to Build a Common Syntactic Kernel for Related Dialects

This article describes the design of a common syntactic description for the core grammar of a group of related dialects. The common description does not rely on an abstract sub-linguistic structure like a metagrammar: it consists in a single FS-LTAG where the actual specific language is included as one of the attributes in the set of attribute types defined for the features. When the lang attribute is instantiated, the selected subset of the grammar is equivalent to the grammar of one dialect. When it is not, we have a model of a hybrid multidialectal linguistic system. This principle is used for a group of creole languages of the West-Atlantic area, namely the French-based Creoles of Haiti, Guadeloupe, Martinique and French Guiana.Comment: 8 pages, 3 figures, 2 tables. LaTeX 2e using the coling08 style (and standard packages like epsf, amssymb, multirow, url...). Proceedings of the 9th International Workshop on Tree Adjoining Grammars and Related Formalisms. Tuebingen, Baden-Wurttemberg, Germany, 6-8 June 200

Le statut du signe iconique entre iconicité et intertextualité

21 pages, 7 figures (parmi lesquelles en vrac un chat, un glyphe aztèque, du vent latéral, un carrefour giratoire, un diable, et un paysan en sabots). Composé avec Microsoft Word.International audienceThe term iconic sign is used to describe a category of semiotic objects which are perceived, and understood, as resembling the object they refer to. However, the intuitive notion of resemblance alone leads soon to a contradictory theory, so a valid theoretical model cannot be founded on it. Moreover, the purported transparency and universality of iconic signs soon meet their limits in practice, and there are many examples of icons failing in their communication purpose. We will examine under which angles various schools of thought and theories contribute to the understanding of the iconic signs (peircean semiotics, structural semiotics, pragmatics), and how their insights may complete one another.On regroupe sous le terme de signe iconique la catégorie d'objets sémiotiques qui sont perçus comme ressemblant à l'objet auxquel ils renvoient. Cependant, la notion intuitive de ressemblance ne suffit pas à fonder un véritable modèle théorique et débouche vite sur des contradictions. En outre, les limites de la transparence et de l'universalité prétendues de l'iconicité sont vite atteintes en pratique, et l'on voit trop souvent des icônes échouer dans leur vocation communicative. Nous examinerons sous quels angles les apports de différentes écoles théoriques (sémiotique peircéenne, sémiotique structurale, pragmatique) éclairent la pratique du signe iconique et comment ces apports se complètent

On the concept of sloped motion for free-floating wave energy converters

A free-floating wave energy converter (WEC) concept whose power take-off (PTO) system reacts against water inertia is investigated herein. The main focus is the impact of inclining the PTO direction on the system performance. The study is based on a numerical model whose formulation is first derived in detail. Hydrodynamics coefficients are obtained using the linear boundary element method package WAMIT. Verification of the model is provided prior to its use for a PTO parametric study and a multi-objective optimization based on a multi-linear regression method. It is found that inclining the direction of the PTO at around 50. to the vertical is highly beneficial for the WEC performance in that it provides a high capture width ratio over a broad region of the wave period range

On the concept of sloped motion for free-floating wave energy converters

A free-floating wave energy converter (WEC) concept whose power take-off (PTO) system reacts against water inertia is investigated herein. The main focus is the impact of inclining the PTO direction on the system performance. The study is based on a numerical model whose formulation is first derived in detail. Hydrodynamics coefficients are obtained using the linear boundary element method package WAMIT. Verification of the model is provided prior to its use for a PTO parametric study and a multi-objective optimization based on a multi-linear regression method. It is found that inclining the direction of the PTO at around 50. to the vertical is highly beneficial for the WEC performance in that it provides a high capture width ratio over a broad region of the wave period range

Evaluation of Epidemic Intelligence Systems Integrated in the Early Alerting and Reporting Project for the Detection of A/H5N1 Influenza Events

Web-based expert systems dedicated to epidemic intelligence were developed to detect health threats. The Early Alerting and Reporting (EAR) project, launched under the Global Health Initiative, aimed at assessing the feasibility and opportunity of pooling seven of those expert systems. A qualitative survey was carried out with EAR participants to document epidemic intelligence strategies and to assess perceptions regarding the performance of participating systems. Timeliness and sensitivity were rated with high scores illustrating the overall perceived value of all systems while weaknesses were underlined especially in terms of representativeness, completeness and flexibility. These findings were corroborated by the quantitative analysis performed on signals potentially related to influenza A/H5N1 events which occurred in March 2010. For the six systems for which this information was available; the detection rate ranged from 31% to 38%, and increased to 72% when considering the virtual combined system. The positive predictive values (PPV) ranged from 3% to 24% and the F1-score ranged from 6% to 27%. These low scores point out false positive signals related to varying abilities of the systems to efficiently sort-out information and reduce background noise. For the seven systems sensitivity ranged from 38% to 72%. An average difference of 23% was observed between the sensitivities calculated for human cases and epizootics, underlining the difficulties to develop an efficient algorithm or a single pathology. The sensitivity increased to 93% when the virtual combined system was considered, clearly illustrating the systems’ complementarities. The average delay between the detection of the A/H5N1 events by the systems and their official reporting by WHO or OIE was 10.2 days (CI95%, 6.7; 13.8). This work illustrates the diversity in implemented epidemic intelligence activities, differences in systems designs and the potential added values and opportunities for synergy: between systems, between users and between systems and users.JRC.G.2-Global security and crisis managemen