Documents OpenAIRE (Open Access Infrastructure for Research in Europe)
http://hdl.handle.net/10230/8581
2019-01-22T04:33:32ZRetractions onto series-parallel posets
http://hdl.handle.net/10230/36343
Retractions onto series-parallel posets
Dalmau, Víctor; Krokhin, Andrei; Larose, Benoit
The poset retraction problem for a poset P is whether a given poset Q containing P as a subposet admits a retraction onto P, that is, whether there is a homomorphism from Q onto P which fixes every element of P. We study this problem for finite series-parallel posets . We present equivalent combinatorial, algebraic, and topological charaterisations of posets for which the problem is tractable, and, for such a poset P , we describe posets admitting a retraction onto P.
2008-01-01T00:00:00ZMajority constraints have bounded pathwidth duality
http://hdl.handle.net/10230/36342
Majority constraints have bounded pathwidth duality
Dalmau, Víctor; Krokhin, Andrei
We study certain constraint satisfaction problems which are the problems of deciding whether there exists a homomorphism from a given relational structure to a fixed structure with a majority polymorphism. We show that such a problem is equivalent to deciding whether the given structure admits a homomorphism from an obstruction belonging to a certain class of structures of bounded pathwidth. This implies that the constraint satisfaction problem for any fixed structure with a majority polymorphism is in NL.
2008-01-01T00:00:00ZOn the overlap between bilingual language control and domain-general executive control
http://hdl.handle.net/10230/36246
On the overlap between bilingual language control and domain-general executive control
Branzi, Francesca Martina, 1984-; Calabria, Marco; Boscarino, Maria Lucrezia; Costa, Albert
We explored the overlap between bilingual language control (bLC) and domain-general executive control (EC) by focusing on inhibitory control processes. We tested 62 bilinguals in linguistic and non-linguistic switching tasks for two types of costs, such as the n − 1 shift cost and the n − 2 repetition cost. In order to explore the involvement of inhibitory control in bLC and EC, we assessed the pattern of switch costs in the two tasks and then we correlated them between tasks. Results showed reduced n − 2 repetition costs as compared to n − 1 shift costs in the linguistic task only, suggesting that small amount of inhibition were deployed when switching between languages. Importantly, neither the n − 1 shift costs nor the n − 2 repetition costs were correlated between tasks. These results, supported by additional evidence from the ex-Gaussian analysis, suggest that inhibitory control is differently involved in bLC and in EC.
2016-01-01T00:00:00ZCompeting engines of growth: innovation and standardization
http://hdl.handle.net/10230/36244
Competing engines of growth: innovation and standardization
Acemoglu, Daron; Gancia, Gino; Zilibotti, Fabrizio
We study a dynamic general equilibrium model where innovation takes the form of the introduction of new goods whose production requires skilled workers. Innovation is followed by a costly process of standardization, where by these new goods are adapted to be produced using unskilled labor. Our framework highlights a number of novel results. First, standardization is both an engine of growth and a potential barrier to it. As a result, growth is an inverse U-shaped function of the standardization rate (and of competition). Second, we characterize the growth and welfare maximizing speed of standardization. We show how optimal protection of intellectual property rights affecting the cost of standardization vary with the skill-endowment, the elasticity of substitution between goods and other parameters. Third, we show that, depending on how competition between innovating and standardizing firms is modelled and on parameter values, a new type of multiplicity of equilibria may arise. Finally, we study the implications of our model for the skill premium and we illustrate novel reasons for linking North–South trade to intellectual property rights protection.
2010-01-01T00:00:00Z