A Full Non-Monotonic Transition System for Unrestricted Non-Projective Parsing

Restricted non-monotonicity has been shown beneficial for the projective arc-eager dependency parser in previous research, as posterior decisions can repair mistakes made in previous states due to the lack of information. In this paper, we propose a novel, fully non-monotonic transition system based on the non-projective Covington algorithm. As a non-monotonic system requires exploration of erroneous actions during the training process, we develop several non-monotonic variants of the recently defined dynamic oracle for the Covington parser, based on tight approximations of the loss. Experiments on datasets from the CoNLL-X and CoNLL-XI shared tasks show that a non-monotonic dynamic oracle outperforms the monotonic version in the majority of languages.Comment: 11 pages. Accepted for publication at ACL 201

Failing and Merging as Competing Alternatives during Times of Financial Distress: Evidence from the Colombian Financial Crisis

This paper studies the determinants of individual bank failures and M&A processes in Colombia during the financial crisis of the late 1990s. Using bank-specific data we estimate competing risk hazards models and find that while profitability and capitalization are the most important determinants of the probability of failing, bank´s size, efficiency and capitalization are the main determinants of the probability of participating in an integration process. All else constant, an increase in capitalization reduces the probability of disappearing, whether due to the occurrence of bankruptcy, a merge or an acquisition. However, a marginal increase in capitalization reduces significantly more the probability of bankruptcy than the probability of integration. This study is the first to present a competing risks hazard model to identify covariates that excerpt significant influence on the probability of failing or merging for banks of an emerging economy.Survival analysis; Competing risk models; Colombia. Classification JEL: G21; G33; G33; C25

Numerical exploration of the influence of neural noise on the psychometric function

The relationship between stimulus intensity and the probability of detecting the presence of the stimulus is described by the psychometrical function. The probabilistic nature of this relationship is based on the stochastic behaviour of sensory neural channels and sensory networks involved in perceptual processing (Kiang 1968). This study tries to establish a continuum of variability across different levels of integration in the central nervous system. Once the opening and closing times of ionic channels was simulated, a threshold to the collective behaviour of voltage-gated ionic channels was imposed in order to generate the spike train of a single neuron. Afterwards, the trains of spikes of different neurons were added up, simulating the activity of a sensory nerve. By adding the activity due to the stimulus to the spontaneous neural behaviour, the psychometric function was simulated using a thresholding approach. The results can replicate the stochastic resonance phenomenon, but also open up the possibility that attentional phenomena can be mediated not only by increasing neural activity (bursting or oscillatory), but also by increasing noise at the neural level

Does the Use of Foreign Currency Derivatives Affect Colombian Firms’ Market Value?

Classic financial theory relies on the absolute perfection of capital markets, which results in one of the milestones of theoretical corporate finance: the firm’s value is invariant to the choice of capital structure. As an extension to the aforementioned proposition by Modigliani and Miller (1958), corporate risk management is also futile. Nevertheless, it is clear that capital markets do not work with absolute perfection. There exist frictions which make risk management decisions essential for the firm’s value. Moreover, derivatives’ market vast importance is a good proxy of the relevance of hedging decisions for corporate finance. There is a remarkable volume of literature which tests the effects of risk management and hedging decisions for the value of the firm, mainly for the US corporate market. However, there is little effort on this subject for markets which work even farther from absolute perfection. This document undertakes such task for the Colombian market. Focused on non-financial firms and the local’s most liquid derivatives market, we find that for a panel of eight large Colombian corporations, the growth rate of Tobin´s Q depends significantly on firm´s size and hedging. Our results suggests that, after controlling for relevant financial variables such as firm´s profitability and leverage, and other variables such as firm´s age, an increase in hedging leads to a higher growth in the firm´s value.Modigliani-Miller, risk management, hedging, firm value, emerging market, Tobin´s Q. Classification JEL: G32, G30, L25.

Multitask Pointer Network for Multi-Representational Parsing

Financiado para publicación en acceso aberto: Universidade da Coruña/CISUG[Abstract] Dependency and constituent trees are widely used by many artificial intelligence applications for representing the syntactic structure of human languages. Typically, these structures are separately produced by either dependency or constituent parsers. In this article, we propose a transition-based approach that, by training a single model, can efficiently parse any input sentence with both constituent and dependency trees, supporting both continuous/projective and discontinuous/non-projective syntactic structures. To that end, we develop a Pointer Network architecture with two separate task-specific decoders and a common encoder, and follow a multitask learning strategy to jointly train them. The resulting quadratic system, not only becomes the first parser that can jointly produce both unrestricted constituent and dependency trees from a single model, but also proves that both syntactic formalisms can benefit from each other during training, achieving state-of-the-art accuracies in several widely-used benchmarks such as the continuous English and Chinese Penn Treebanks, as well as the discontinuous German NEGRA and TIGER datasets.We acknowledge the European Research Council (ERC), which has funded this research under the European Union’s Horizon 2020 research and innovation programme (FASTPARSE, grant agreement No 714150), ERDF/MICINN-AEI (ANSWER-ASAP, TIN2017-85160-C2-1-R; SCANNER-UDC, PID2020-113230RB-C21), Xunta de Galicia, Spain (ED431C 2020/11), and Centro de Investigación de Galicia “CITIC”, funded by Xunta de Galicia, Spain and the European Union (ERDF - Galicia 2014–2020 Program), by grant ED431G 2019/01. Funding for open access charge: Universidade da Coruña / CISUGXunta de Galicia; ED431C 2020/11Xunta de Galicia; ED431G 2019/0

An efficient dynamic oracle for unrestricted non-projective parsing

We define a dynamic oracle for the Covington non-projective dependency parser. This is not only the first dynamic oracle that supports arbitrary non-projectivity, but also considerably more efficient (O(n)) than the only existing oracle with restricted non-projectivity support. Experiments show that training with the dynamic oracle significantly improves parsing accuracy over the static oracle baseline on a wide range of treebanks.Ministerio de Economía y Competitividad | Ref. FFI2014-51978-C2-1-RMinisterio de Economía y Competitividad | Ref. FFI2014-51978-C2-2-RXunta de Galicia | Ref. R2014/03