22,456 research outputs found
The value of coskewness in evaluating mutual funds
Recent asset pricing studies demonstrate the relevance of incorporating the coskewness in Asset
Pricing Models, and illustrate how this component helps to explain the time variation of ex-ante
market risk premiums. This paper analyzes the role of coskewness in mutual funds performance
evaluation. We find evidence that adding a coskewness factor is economically and statistically
significant. We document that some managers are managing the coskewness and show, in general,
a persistent behaviour on time in their coskewness policy. One of the most striking results is that
many negative (positive) alpha funds measured relative to the CAPM risk adjustments would be
reclassified as positive (negative) alpha funds using a model with coskewness. Therefore, a ranking
of funds based on risk adjusted returns without considering coskewness would generate an
erroneous classification. Moreover, some fund characteristics, such as the turnover ratio or the
category, are related to the likelihood of managing coskewness
Constituent Parsing as Sequence Labeling
We introduce a method to reduce constituent parsing to sequence labeling. For
each word w_t, it generates a label that encodes: (1) the number of ancestors
in the tree that the words w_t and w_{t+1} have in common, and (2) the
nonterminal symbol at the lowest common ancestor. We first prove that the
proposed encoding function is injective for any tree without unary branches. In
practice, the approach is made extensible to all constituency trees by
collapsing unary branches. We then use the PTB and CTB treebanks as testbeds
and propose a set of fast baselines. We achieve 90.7% F-score on the PTB test
set, outperforming the Vinyals et al. (2015) sequence-to-sequence parser. In
addition, sacrificing some accuracy, our approach achieves the fastest
constituent parsing speeds reported to date on PTB by a wide margin.Comment: EMNLP 2018 (Long Papers). Revised version with improved results after
fixing evaluation bu
A non-projective greedy dependency parser with bidirectional LSTMs
The LyS-FASTPARSE team presents BIST-COVINGTON, a neural implementation of
the Covington (2001) algorithm for non-projective dependency parsing. The
bidirectional LSTM approach by Kipperwasser and Goldberg (2016) is used to
train a greedy parser with a dynamic oracle to mitigate error propagation. The
model participated in the CoNLL 2017 UD Shared Task. In spite of not using any
ensemble methods and using the baseline segmentation and PoS tagging, the
parser obtained good results on both macro-average LAS and UAS in the big
treebanks category (55 languages), ranking 7th out of 33 teams. In the all
treebanks category (LAS and UAS) we ranked 16th and 12th. The gap between the
all and big categories is mainly due to the poor performance on four parallel
PUD treebanks, suggesting that some `suffixed' treebanks (e.g. Spanish-AnCora)
perform poorly on cross-treebank settings, which does not occur with the
corresponding `unsuffixed' treebank (e.g. Spanish). By changing that, we obtain
the 11th best LAS among all runs (official and unofficial). The code is made
available at https://github.com/CoNLL-UD-2017/LyS-FASTPARSEComment: 12 pages, 2 figures, 5 table
Harry Potter and the Action Prediction Challenge from Natural Language
We explore the challenge of action prediction from textual descriptions of
scenes, a testbed to approximate whether text inference can be used to predict
upcoming actions. As a case of study, we consider the world of the Harry Potter
fantasy novels and inferring what spell will be cast next given a fragment of a
story. Spells act as keywords that abstract actions (e.g. 'Alohomora' to open a
door) and denote a response to the environment. This idea is used to
automatically build HPAC, a corpus containing 82,836 samples and 85 actions. We
then evaluate different baselines. Among the tested models, an LSTM-based
approach obtains the best performance for frequent actions and large scene
descriptions, but approaches such as logistic regression behave well on
infrequent actions.Comment: NAACL 2019 (short papers
Information Policies in Spain: Towards the New “Information Society”
The concept of a society based on information and knowledge is becoming the norm in every country, including Spain. The need to have well-designed information policies that allow us to come to terms with the new upsurge of
media, technology and services that has taken place in our society is discussed first. Information policies required by
these changes in society have been implemented in Spain and are described in relation to the new challenges of the
“Society of Knowledge.” Similarly, the background and past efforts made in the field of information policy in Spain are
analysed, along with the latest government projects that comprise an attempt to get this country to form part of the “Information Society” with the help of the supra-national information policy of the European Union
Do Quasi-Hyperbolic Preferences Explain Academic Procrastination? An Empirical Evaluation
Traditional neoclassical thought fails to explain questions such as problems of self-control. Behavioural
economics have explained these matters on the basis of the intertemporal preferences of individuals
and, specifically, the so-called (β, δ) model which emphasises present bias. This opens the way
to the analysis of new situations in which people can adopt incorrect indecisions that make it necessary
for the government to intervene. The literature which has developed the (β, δ) model and its implications
has generated a categorisation of people that is widely used but which lacks a systematic empirical
evaluation. It is important to value the need for this public action. In this article, we develop a
method which makes it possible to verify the main implications that this model has to explain the
procrastination of university students. Using an experimental time discount task with real monetary
incentives, we estimate the students’ β and δ parameters and we analyse their correlation with their
answers to a series of questions concerning how they plan to study for an exam. The results are ambiguous
given that they back some of the model’s conclusions but reject others, including a number of
the most basic ones, such as the relation between present biases and some of the categories of people,
these being essential to predict their behaviour
Power Management of a Plug-in Hybrid Electric Vehicle Based on Cycle Energy Estimation
2012 Workshop on Engine and Powertrain Control,Simulation and ModelingThe International Federation of Automatic ControlRueil-Malmaison, France, October 23-25, 2012Plug-in Hybrid Electric Vehicles (PHEV) are being investigated in many research and development programs motivated by the urgent need for more fuel-efficient vehicles that produce fewer harmful emissions. There are many potential advantages of hybridization such as the improvement of transient power demand, the ability of regenerative braking and the opportunities for optimization of the vehicle efficiency. The coordination among the various power sources requires a high level of control in the vehicle. In order to solve the power management problem, the controller proposed in this work is divided into two levels: the upper one calculates the power that must be supplied by the engine at each moment taking into account the estimation of the energy that must be supplied by the powertrain until the end of the journey. The lower one manages the torque/speed set points for all the devices. Besides, the operation modes are changed according to some heuristic rules. Several simulation results are presented, showing that the proposed control strategy can provide good performance with low computational load
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