Parsing with CYK over Distributed Representations

Syntactic parsing is a key task in natural language processing. This task has been dominated by symbolic, grammar-based parsers. Neural networks, with their distributed representations, are challenging these methods. In this article we show that existing symbolic parsing algorithms can cross the border and be entirely formulated over distributed representations. To this end we introduce a version of the traditional Cocke-Younger-Kasami (CYK) algorithm, called D-CYK, which is entirely defined over distributed representations. Our D-CYK uses matrix multiplication on real number matrices of size independent of the length of the input string. These operations are compatible with traditional neural networks. Experiments show that our D-CYK approximates the original CYK algorithm. By showing that CYK can be entirely performed on distributed representations, we open the way to the definition of recurrent layers of CYK-informed neural networks.Comment: The algorithm has been greatly improved. Experiments have been redesigne

Trade Integration, Firm Selection and the Costs of Non-Europe

In models with heterogeneous firms trade integration has a positive impact on aggregate productivity through the selection of the best firms as import competition drives the least productive ones out of the market. To quantify the impact of firm selection on productivity, we calibrate and simulate a multi-country multi-sector model with monopolistic competition and variable markups using firm-level data and aggregate trade figures on a panel of 11 EU countries. We find that EU trade has a sizeable impact on aggregate productivity. In 2000 the introduction of prohibitive trade barriers would have caused an average productivity loss of roughly 13 per cent, whereas a reduction of intra-EU trade costs by 5 per cent would have generated a productivity gain of roughly 2 per cent. Productivity losses and gains, however, vary a lot across countries and sectors depending on market accessibility and trade costs. We provide evidence that our results are robust to alternative distance and productivity measures.European integration, firm-level data, firm selection, gains from trade, total factor productivity

Productivity and Firm Selection: Quantifying the “New” Gains from Trade

We discuss how standard computable equilibrium models of trade policy can be enriched with selection effects without missing other important channels of adjustment. This is achieved by estimating and simulating a partial equilibrium model that accounts for a number of real world effects of trade liberalisation: richer availability of product varieties; tougher competition and weaker market power of firms; better exploitation of economies of scale; and, of course, efficiency gains via the selection of the most efficient firms. The model is estimated on E.U. data and simulated in counterfactual scenarios that capture several dimensions of European integration. Simulations suggest that the gains from trade are much larger in the presence of selection effects. Even in a relatively integrated economy as the E.U., dismantling residual trade barriers would deliver relevant welfare gains stemming from lower production costs, smaller markups, lower prices, larger firm scale and richer product variety. We believe our analysis provides enough ground to support the inclusion of firm heterogeneity and selection effects in the standard toolkit of trade policy evaluation.European Integration, Firm-level Data, Firm Selection, Gains from Trade, Total Factor Productivity

Productivity and firm selection: intra- vs international trade

Recent theoretical models predict gains from international trade coming from intra-industry reallocations, due to a firm selection effect. In this paper we answer two related questions. First, what is the magnitude of this selection effect, and how does it compare to that of intra-national trade? Second, would the removal of 'behind-the-border' trade frictions between integrated EU countries lead to large productivity gains? To answer these questions, we extend and calibrate the Melitz and Ottaviano (2007) model on productivity and trade data for European economies in 2000, and simulate counterfactual trade liberalization scenarios. We consider 11 EU countries and a total of 31 economies, including 21 French regions. Our first result is that, in the French case, international trade has a sizeable impact on aggregate productivity, but smaller than that of intra-national trade. Second, substantial productivity gains (around 20%) can be expected from 'behind-the-border' integration. In both experiments, we predict the corresponding variations in average prices, markups, quantities and profits. We show that the model fits sales and exports data reasonably well, and we perform a number of robustness checks. We also suggest some explanations for the substantial cross-economy and cross-industry variations in our estimates of productivity gains, highlighting the importance of accessibility and competitiveness.European integration, intra-national trade, firm-level data, firm selection, gains from trade, total factor productivity

Localisation of Dirac eigenmodes and confinement in gauge theories: the Roberge-Weiss transition

Ample numerical evidence from lattice calculations shows a strong connection between the confining properties of gauge theories at finite temperature and the localisation properties of the low-lying Dirac eigenmodes. In this contribution we discuss recent progress on this topic, focussing on results for QCD at imaginary chemical potential ${\mu}_I/T = \pi$ at temperatures above the Roberge-Weiss transition temperature. These confirm the general picture of low modes turning from delocalised to localised at the deconfinement transition, in a previously unexplored setup with a genuine, physical transition in the presence of dynamical fermions. This further supports the use of Dirac eigenmodes as a tool to investigate the mechanisms behind confinement and the deconfinement transition.Comment: 8 pages, 4 figures; contribution to the proceedings of the XVth Quark Confinement and Hadron Spectrum conference (ConfXV), 1-6 August 2022, University of Stavanger, Stavanger (Norway