Fiscal indicators - Proceedings of the the Directorate-General for Economic and Financial Affairs Workshop held on 22 September 2006 in Brussels

Fiscal indicators are the backbone of effective fiscal policy-making, including the coordination and surveillance of budgetary policy at the EU level. The quality and success of the EU surveillance framework, in particular the timeliness and appropriateness of any policy recommendation or decision taken in the context of the Stability and Growth Pact (SGP), crucially depend on the quality of its diagnostic instruments. The right conclusions can only be drawn if the underlying analysis is comprehensive and accurate.fiscal indicators, government budget, EU fiscal surveillance, sustainability of fiscal policy, cyclically adjusted budget balance, Larch, Nogueira Martins

How reliable are the statistics for the Stability and Growth Pact?

The aim of this paper is to assess the reliability of the government deficit and debt figures reported to the European Commission by Member States. Reliability is one of the several dimensions of quality in statistics; it refers to the magnitudes of data revisions after the publication of the first outcomes. The measurement of the data reliability and inference about potential future revisions are particularly relevant for fiscal surveillance in the EU since statistical institutes take a long time - usually four years - to provide final data, while the decisions on the Stability and Growth Pact context are taken on the basis of the first estimates available shortly after the end of each year. The paper shows that there are very significant differences in reliability among Member States and indicates the margins of uncertainty in relation to the most recent years' data. It also compares the reliability of deficit and debt figures; checks that the shift from ESA79 to ESA95 did not generally harm the reliability of data and suggests that the size of deficits may have an impact on the way statistical offices revise data.reliability, quality of statistics, Stability and Growth Pact, government deficit, Gordo Mora, Nogueira Martins

The first analytical expression to estimate photometric redshifts suggested by a machine

We report the first analytical expression purely constructed by a machine to determine photometric redshifts ($z_{\rm phot}$) of galaxies. A simple and reliable functional form is derived using $41,214$ galaxies from the Sloan Digital Sky Survey Data Release 10 (SDSS-DR10) spectroscopic sample. The method automatically dropped the $u$ and $z$ bands, relying only on $g$, $r$ and $i$ for the final solution. Applying this expression to other $1,417,181$ SDSS-DR10 galaxies, with measured spectroscopic redshifts ($z_{\rm spec}$), we achieved a mean $\langle (z_{\rm phot} - z_{\rm spec})/(1+z_{\rm spec})\rangle\lesssim 0.0086$ and a scatter $\sigma_{(z_{\rm phot} - z_{\rm spec})/(1+z_{\rm spec})}\lesssim 0.045$ when averaged up to $z \lesssim 1.0$. The method was also applied to the PHAT0 dataset, confirming the competitiveness of our results when faced with other methods from the literature. This is the first use of symbolic regression in cosmology, representing a leap forward in astronomy-data-mining connection.Comment: 6 pages, 4 figures. Accepted for publication in MNRAS Letter

Classical Radiation Reaction in Particle-In-Cell Simulations

Under the presence of ultra high intensity lasers or other intense electromagnetic fields the motion of particles in the ultrarelativistic regime can be severely affected by radiation reaction. The standard particle-in-cell (PIC) algorithms do not include radiation reaction effects. Even though this is a well known mechanism, there is not yet a definite algorithm nor a standard technique to include radiation reaction in PIC codes. We have compared several models for the calculation of the radiation reaction force, with the goal of implementing an algorithm for classical radiation reaction in the Osiris framework, a state-of-the-art PIC code. The results of the different models are compared with standard analytical results, and the relevance/advantages of each model are discussed. Numerical issues relevant to PIC codes such as resolution requirements, application of radiation reaction to macro particles and computational cost are also addressed. The Landau and Lifshitz reduced model is chosen for implementation.Comment: 12 pages, 8 figure

Exploiting Resolution-based Representations for MaxSAT Solving

Most recent MaxSAT algorithms rely on a succession of calls to a SAT solver in order to find an optimal solution. In particular, several algorithms take advantage of the ability of SAT solvers to identify unsatisfiable subformulas. Usually, these MaxSAT algorithms perform better when small unsatisfiable subformulas are found early. However, this is not the case in many problem instances, since the whole formula is given to the SAT solver in each call. In this paper, we propose to partition the MaxSAT formula using a resolution-based graph representation. Partitions are then iteratively joined by using a proximity measure extracted from the graph representation of the formula. The algorithm ends when only one partition remains and the optimal solution is found. Experimental results show that this new approach further enhances a state of the art MaxSAT solver to optimally solve a larger set of industrial problem instances