About the freedom of free forms

p. 907-913This paper deals with the arrival of freedom at the world of structures giving birth a new generation of forms: the free forms. Its purpose is to analyze, to discuss and to comment critically this singular fact as well as their implications on the designers' task. It is more a philosophical than a technical paper. For centuries man has imagined new forms for their structures but he has not been always able to analyze and to build them. Before the arrival of the electronic calculus, the representation and analysis of structural forms could be limited to those ones belonging to the Euclidean Geometry. The computers broke those limitations and they gave wide freedom to the designers to conceive a new generation of forms; these new forms were called "free forms". Nowadays any form imagined can be represented, it can be analyzed and it can be built. Nevertheless not any imagined form can become a structural free form. Perhaps it could be a beautiful sculptural form, but not necessarily a structural one. For being a structural form, the inescapable laws of the mechanics must be satisfied. Moreover a structural free form can become an architectural free form just only when aesthetical, functional, environmental and social requirements, among others, are accomplished. Freedom has widened the horizons of creativity for the designers' task. Simultaneously new responsibilities have come altogether with this freedom. Today free form designers face permanent challenges; designers must be familiar with the menus of new and multiple tools created by the modern technology and they must be trained to make the right use of them. They must handle those wide menus in order to select the most appropriated options to generate, to model and to analyze the new free forms. At the same time they must select the most appropriated new materials and techniques to build these free forms. Finally, designer must be fully conscious of the high impact of their engineering and architectural works on the people and physical environment without forgetting their commitment to the society.Andres, OA. (2010). About the freedom of free forms. Editorial Universitat Politècnica de València. http://hdl.handle.net/10251/695

Yang-Mills Chern-Simons Corrections From the Pure Spinor Superstring

Nilpotency of the pure spinor BRST operator in a curved background implies superspace equations of motion for the background. By computing one-loop corrections to nilpotency for the heterotic sigma model, the Yang-Mills Chern-Simons corrections to the background are derived.Comment: 25 pages, harvmac tex, 15 diagrams; references adde

Integrating e-commerce standards and initiatives in a multi-layered ontology

The proliferation of different standards and joint initiatives for the classification of products and services (UNSPSC, e-cl@ss, RosettaNet, NAICS, SCTG, etc.) reveals that B2B markets have not reached a consensus on the coding systems, on the level of detail of their descriptions, on their granularity, etc. This paper shows how these standards and initiatives, which are built to cover different needs and functionalities, can be integrated in an ontology using a common multi-layered knowledge architecture. This multi-layered ontology will provide a shared understanding of the domain for applications of e-commerce, allowing the information sharing between heterogeneous systems. We will present a method for designing ontologies from these information sources by automatically transforming, integrating and enriching the existing vocabularies with the WebODE platform. As an illustration, we show an example on the computer domain, presenting the relationships between UNSPSC, e-cl@ss, RosettaNet and an electronic catalogue from an e-commerce platform

Intergenerational transmission of welfare dependency: The effects of length of exposure

It is well documented that a positive correlation exists between receiving welfare as a child and depending on welfare as an adult. However, previous studies have not been able to explore many aspects of this relationship. This paper uses a unique administrative dataset for California, which follows welfare recipients since their teenage years until early adulthood, to study the causal effects of different lengths of welfare exposure as a child (conditional on welfare receipt) on future welfare dependency as a young adult. The econometric analyses in this paper use a recently developed method from the program evaluation literature, based on the estimation of a generalized propensity score (GPS). As in the binary-treatment case the GPS permits removing the biases associated with differences in the observed characteristics of individuals. In addition, for some analyses, family-level unobserved heterogeneity is controlled for by relying on pairs of siblings exposed to different lengths of exposure. The results show that there is no causal effect of length of exposure on future welfare dependency, nor on teenage childbearing. Conditional on teenage childbearing, there are no effects of length of exposure on adult welfare dependency either, but this dependency is almost three times larger for teenage mothers than for non-mothers. All results hold when controlling for unobserved heterogeneity. The results indicate that policies like time-limits are not likely to reduce the intergenerational correlation of welfare dependency.Welfare Dependency, Continuous Treatments

Evaluating Knowledge Representation and Reasoning Capabilites of Ontology Specification Languages

The interchange of ontologies across the World Wide Web (WWW) and the cooperation among heterogeneous agents placed on it is the main reason for the development of a new set of ontology specification languages, based on new web standards such as XML or RDF. These languages (SHOE, XOL, RDF, OIL, etc) aim to represent the knowledge contained in an ontology in a simple and human-readable way, as well as allow for the interchange of ontologies across the web. In this paper, we establish a common framework to compare the expressiveness of "traditional" ontology languages (Ontolingua, OKBC, OCML, FLogic, LOOM) and "web-based" ontology languages. As a result of this study, we conclude that different needs in KR and reasoning may exist in the building of an ontology-based application, and these needs must be evaluated in order to choose the most suitable ontology language(s)

Well-posed forms of the 3+1 conformally-decomposed Einstein equations

We show that well-posed, conformally-decomposed formulations of the 3+1 Einstein equations can be obtained by densitizing the lapse and by combining the constraints with the evolution equations. We compute the characteristics structure and verify the constraint propagation of these new well-posed formulations. In these formulations, the trace of the extrinsic curvature and the determinant of the 3-metric are singled out from the rest of the dynamical variables, but are evolved as part of the well-posed evolution system. The only free functions are the lapse density and the shift vector. We find that there is a 3-parameter freedom in formulating these equations in a well-posed manner, and that part of the parameter space found consists of formulations with causal characteristics, namely, characteristics that lie only within the lightcone. In particular there is a 1-parameter family of systems whose characteristics are either normal to the slicing or lie along the lightcone of the evolving metric.Comment: 22 page

WebPicker: Knowledge Extraction from Web Resources

We show how information distributed in several web resources and represented in different restricted languages can be extracted from its original sources and transformed into a common knowledge model represented in XML using WebPicker. This information, which has been built to cover different needs and functionalities, can be later imported into WebODE, integrated, enriched and exported into different representation formats using WebODE specific modules. We show a case study in the e-commerce domain, using products and services standards from several organizations and/or joint initiatives of industrial and services companies, and a product catalogue from an e-commerce platform

Guidelines to Study Differences in Expressiveness between Ontology Specification Languages: A Case Of Study

We focus on our experiences on translating ontologies between two ontology languages, FLogic and Ontolingua, in the framework of Methontology and ODE. Rather than building "ad hoc" translators between languages or using KIF, our option consists of translating through ODE intermediate representations. So, we have built direct translators from ODE intermediate representations to Ontolingua and FLogic, and we have also built reverse translators from these two languages to ODE intermediate representations. Expressiveness of the target languages is the main feature to analyse when automatically generating ontologies from ODE intermediate representations. Therefore, we analyse the expressiveness of Ontolingua and FLogic for creating classes, instances, relations, functions and axioms, which are the essential components in ontologies. The motivation for this analysis can be found in the (KA)² initiative and can be easily extended to any other domains and languages