Europe and China’s Belt and Road Initiative: Growing Concerns, More Strategy. Egmont Security Policy Brief No. 118 November 2019

Geopolitical shifts are engendering a transformation of the globalized economic order that has flourished in the post-Cold War period. This trend runs deep and raises structural challenges, - such as the rivalry between different economic models, the competition for technological leadership as well as control over physical and digital connectivity. As the European Union (EU) now accounts for a lower share of world trade, investment, currency holdings, defence expenditure, and development assistance, this shift has also produced growing concerns about the EU’s relative decline and its future economic security 1

A Backward Algorithm for the Multiprocessor Online Feasibility of Sporadic Tasks

The online feasibility problem (for a set of sporadic tasks) asks whether there is a scheduler that always prevents deadline misses (if any), whatever the sequence of job releases, which is a priori} unknown to the scheduler. In the multiprocessor setting, this problem is notoriously difficult. The only exact test for this problem has been proposed by Bonifaci and Marchetti-Spaccamela: it consists in modelling all the possible behaviours of the scheduler and of the tasks as a graph; and to interpret this graph as a game between the tasks and the scheduler, which are seen as antagonistic players. Then, computing a correct scheduler is equivalent to finding a winning strategy for the `scheduler player', whose objective in the game is to avoid deadline misses. In practice, however this approach is limited by the intractable size of the graph. In this work, we consider the classical attractor algorithm to solve such games, and introduce antichain techniques to optimise its performance in practice and overcome the huge size of the game graph. These techniques are inspired from results from the formal methods community, and exploit the specific structure of the feasibility problem. We demonstrate empirically that our approach allows to dramatically improve the performance of the game solving algorithm.Comment: Long version of a conference paper accepted to ACSD 201

Especialització i reinterpretació en les expressions idiomàtiques

It can be shown that the semantic specialization of idioms is a matter of degree, and that semantic interpretation is not just a question of bottom-up compositionality or literal-to-figurative transfer: the reinterpretation processes that can be observed in idioms point to the existence of top-down and figurative-to-literal interpretati

Dynamics and Coalitions in Sequential Games

We consider N-player non-zero sum games played on finite trees (i.e., sequential games), in which the players have the right to repeatedly update their respective strategies (for instance, to improve the outcome wrt to the current strategy profile). This generates a dynamics in the game which may eventually stabilise to a Nash Equilibrium (as with Kukushkin's lazy improvement), and we argue that it is interesting to study the conditions that guarantee such a dynamics to terminate. We build on the works of Le Roux and Pauly who have studied extensively one such dynamics, namely the Lazy Improvement Dynamics. We extend these works by first defining a turn-based dynamics, proving that it terminates on subgame perfect equilibria, and showing that several variants do not terminate. Second, we define a variant of Kukushkin's lazy improvement where the players may now form coalitions to change strategies. We show how properties of the players' preferences on the outcomes affect the termination of this dynamics, and we thereby characterise classes of games where it always terminates (in particular two-player games).Comment: In Proceedings GandALF 2017, arXiv:1709.0176

The EU and China: Modest signs of convergence? Egmont Security Policy Brief No. 101

Against a background in which the United States is increasingly drawing into question its commitments to free trade and the global commons, the challenge for the EU and China is to deal with a global governance system that is evolving from a multilateral system centred around the US into a more diffuse system resting on the three strong trading poles: China, the EU and the US