Normal forms for Answer Sets Programming

Normal forms for logic programs under stable/answer set semantics are introduced. We argue that these forms can simplify the study of program properties, mainly consistency. The first normal form, called the {\em kernel} of the program, is useful for studying existence and number of answer sets. A kernel program is composed of the atoms which are undefined in the Well-founded semantics, which are those that directly affect the existence of answer sets. The body of rules is composed of negative literals only. Thus, the kernel form tends to be significantly more compact than other formulations. Also, it is possible to check consistency of kernel programs in terms of colorings of the Extended Dependency Graph program representation which we previously developed. The second normal form is called {\em 3-kernel.} A 3-kernel program is composed of the atoms which are undefined in the Well-founded semantics. Rules in 3-kernel programs have at most two conditions, and each rule either belongs to a cycle, or defines a connection between cycles. 3-kernel programs may have positive conditions. The 3-kernel normal form is very useful for the static analysis of program consistency, i.e., the syntactic characterization of existence of answer sets. This result can be obtained thanks to a novel graph-like representation of programs, called Cycle Graph which presented in the companion article \cite{Cos04b}.Comment: 15 pages, To appear in Theory and Practice of Logic Programming (TPLP

Trade performances and technology in the enlarged European Union

We analyse the role of the enlargement process of the European Union as a factor fostering international competitiveness of EU Member States. We argue that the economic integration process has partially reduced the technological gap between old and new EU Member States, and this pattern of technological innovation can partially explain the strong impulse on the export dynamics of European countries. We have built an augmented gravity model by including the role of technological innovation, proxied by the stock of knowledge at the sector level. By using a dynamic panel data estimator we find three main empirical evidences. First, the enlargement process has produced an overall larger positive impact on export flows for new members than for old ones, and more importantly that sectors with the higher technological content have received the strongest impulse. Second, the augmented gravity model allows shaping the crucial role of technological innovation in fostering export competitiveness. Third, this impact seems to be stronger for old EU member states than for new ones. The policy implication we derive is that the more the new EU members catch up technologically as a result of the integration process, the more they will benefit in terms of economic development.EU enlargement, gravity model, international trade, economic integration, technological innovation

In Memoriam : Anne Marty (1947-2018)

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La découverte de Robert Louis Vesque, écrivain algérien pied-noir inédit d'avant l'exode

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Agri-food exports and the enlarged european union

This paper explores agri-food export dynamics in New Member States (NMS) and Old Member States (OMS) of the European Union during the enlargement process. A quality-oriented survey is conducted by developing an original analytical framework which combines information from trade similarity analysis with elements from the sophistication literature. Country and sector specific features seem to emerge, revealing a more complex picture than that produced by aggregated trade analysis. While for some NMS agri-food exports, patterns converge towards OMS with regard to size, competitiveness and quality improvement process, for other NMS, a low-quality trap seems to prevail.Agri-food sector, export dynamics, EU enlargement, quality upgrading

Cooperative and non-cooperative solutions to carbon leakage

A modified version of the CGE GTAP-E model is developed for assessing the economic and carbon emissions effects related to alternative policy measures implemented with the aim of reducing carbon leakage. We explore a set of scenarios, comparing solutions where Annex I countries introduce exogenously or endogenously determined carbon border taxes in order to solve the carbon leakage problem unilaterally. Results provide evidence on the scarce effectiveness of carbon tariffs in reducing carbon leakage and enhancing economic competitiveness, while they have large negative welfare effects not only on the Non-Annex countries, but also on certain Annex I countriesCarbon Leakage, Carbon Border Tax, GTAP-E model

Lebesgue density and exceptional points

Work in the measure algebra of the Lebesgue measure on N2 : for comeagre many [A] the set of points x such that the density of x in A is not defined is \u3a30 3-complete; for some compact K the set of points x such that the density of x in K exists and it is different from 0 or 1 is \u3a00 3-complete; the set of all [K] with K compact is \u3a00 3-complete. There is a set (which can be taken to be open or closed) in \u211d such that the density of any point is either 0 or 1, or else undefined. Conversely, if a subset of \u211dn is such that the density exists at every point, then the value 1/2 is always attained on comeagre many points of the measurable frontier. On the route to these results we show that the Cantor space can be embedded in a measured Polish space in a measure-preserving fashio