The democratisation of party leadership selection: the Portuguese experience

In recent years, members of established political parties have received increased powers to select candidates and leaders. Several explanations have been advanced to account for this trend, focusing on the evolution of the political system, the characteristics of party systems or intra-party dynamics. The aim of this article is to examine the introduction of democratising reforms for leadership selection in Portuguese parties. Despite the high degree of centralisation and the low levels of internal participation, all governing parties have expanded members’ rights during the last decade. The main findings suggest that party leaders have decided to change methods for leadership selection mainly for instrumental purposes in order to consolidate their internal power or gain electoral benefits. Moreover, this organisational transformation has had reduced effects on the internal party functioning. Regardless of these similarities, the data show that there are important differences between parties with regard to levels of participation and internal competition

Inductive Logic Programming in Databases: from Datalog to DL+log

In this paper we address an issue that has been brought to the attention of the database community with the advent of the Semantic Web, i.e. the issue of how ontologies (and semantics conveyed by them) can help solving typical database problems, through a better understanding of KR aspects related to databases. In particular, we investigate this issue from the ILP perspective by considering two database problems, (i) the definition of views and (ii) the definition of constraints, for a database whose schema is represented also by means of an ontology. Both can be reformulated as ILP problems and can benefit from the expressive and deductive power of the KR framework DL+log. We illustrate the application scenarios by means of examples. Keywords: Inductive Logic Programming, Relational Databases, Ontologies, Description Logics, Hybrid Knowledge Representation and Reasoning Systems. Note: To appear in Theory and Practice of Logic Programming (TPLP).Comment: 30 pages, 3 figures, 2 tables

Price Dispersion in the Housing Market: The Role of Bargaining and Search Costs

This paper develops a matching model à la Pissarides (2000) in order to explain a basic fact of housing markets: price dispersion. The variance in house prices is basically due to both the ex-ante heterogeneity of the parties (i.e., bargaining power, tastes, asymmetric information) and the search costs of buyers and sellers. In fact, sellers and buyers spend time and money before concluding the deal. Furthermore, the house price is substantially determined by bargaining between the parties. These factors affect the selling price and lead to price dispersion. This simple theoretical model is able to take these distinctive features of the housing markets into account.

The unemployment volatility puzzle: the role of the underground economy

Relying on the non-negligible role played by the underground economy in the labour market fluctuations, this paper extends the standard matching model à la Mortensen-Pissarides by introducing an underground sector along with an endogenous sector choice for both entrepreneurs and workers. These modifications improve the quantitative properties of the standard matching model, thus providing a possible explanation for the unemployment volatility puzzle.unemployment and vacancies volatility; productivity and job destruction shocks; underground economy; shadow economy; hidden economy; matching models.