160,905 research outputs found
Multi-Dimensional Inheritance
In this paper, we present an alternative approach to multiple inheritance for
typed feature structures. In our approach, a feature structure can be
associated with several types coming from different hierarchies (dimensions).
In case of multiple inheritance, a type has supertypes from different
hierarchies. We contrast this approach with approaches based on a single type
hierarchy where a feature structure has only one unique most general type, and
multiple inheritance involves computation of greatest lower bounds in the
hierarchy. The proposed approach supports current linguistic analyses in
constraint-based formalisms like HPSG, inheritance in the lexicon, and
knowledge representation for NLP systems. Finally, we show that
multi-dimensional inheritance hierarchies can be compiled into a Prolog term
representation, which allows to compute the conjunction of two types
efficiently by Prolog term unification.Comment: 9 pages, styles: a4,figfont,eepic,eps
How has the macroeconomic imbalances procedure worked in practice to improve the resilience of the euro area? March 24 2020
This paper shows how the Macroeconomic Imbalances Procedure (MIP) could be streamlined and its underlying conceptual framework clarified. Implementation of the country-specific recommendations is low; their internal consistency is sometimes missing; despite past reforms, the MIP remains largely a countryby-country approach running the risk of aggravating the deflationary bias in the euro area. We recommend to streamline the scoreboard around a few meaningful indicators, involve national macro-prudential and productivity councils, better connect the various recommendations, simplify the language and further involve the Commission into national policy discussions. This document was prepared for the Economic Governance Support Unit at the request of the ECON Committee
What lies behind the "Too-Small-To-Survive" banks
It is a common place that during financial crises, like the one started in 2007, authorities provide substantial financial support to some problem banks, whilst at the same time let several others to go bankrupt. Is this happening because some particular banks are considered important and big enough to save, whereas some others are perceived as being âToo-Small-To-Surviveâ? Is the size of banks the fundamental factor that makes authorities to treat them differently, or it is also that some banks perform poorly and are not capable of withstanding some considerable shocks whatsoever? Our study provides concrete answers to these questions thus filling part of the void in the existing literature. A short- and a long-run positive relationship between size and performance is documented regardless of the level of bank soundness (healthy vs. failed and assisted banks) under scrutiny. Importantly, we pose and lend support to the âToo-Small-To-Surviveâ hypothesis according to which the impact of bank performance on failure probability strongly depends on size. Evidence shows that authorities tend not to save banks whose size is below some specific threshold
Quantifying knowledge exchange in R&D networks: A data-driven model
We propose a model that reflects two important processes in R&D activities of
firms, the formation of R&D alliances and the exchange of knowledge as a result
of these collaborations. In a data-driven approach, we analyze two large-scale
data sets extracting unique information about 7500 R&D alliances and 5200
patent portfolios of firms. This data is used to calibrate the model parameters
for network formation and knowledge exchange. We obtain probabilities for
incumbent and newcomer firms to link to other incumbents or newcomers which are
able to reproduce the topology of the empirical R&D network. The position of
firms in a knowledge space is obtained from their patents using two different
classification schemes, IPC in 8 dimensions and ISI-OST-INPI in 35 dimensions.
Our dynamics of knowledge exchange assumes that collaborating firms approach
each other in knowledge space at a rate for an alliance duration .
Both parameters are obtained in two different ways, by comparing knowledge
distances from simulations and empirics and by analyzing the collaboration
efficiency . This is a new measure, that takes also in
account the effort of firms to maintain concurrent alliances, and is evaluated
via extensive computer simulations. We find that R&D alliances have a duration
of around two years and that the subsequent knowledge exchange occurs at a very
low rate. Hence, a firm's position in the knowledge space is rather a
determinant than a consequence of its R&D alliances. From our data-driven
approach we also find model configurations that can be both realistic and
optimized with respect to the collaboration efficiency .
Effective policies, as suggested by our model, would incentivize shorter R&D
alliances and higher knowledge exchange rates.Comment: 35 pages, 10 figure
Sustainability in Software Engineering
The intersection between software engineering re- search and the problems related to sustainability and green IT has been the subject of increasing attention. In spite of that, we observe that sustainability is still not clearly defined, or understood, in the field of software engineering. This lack of clarity leads to confusion about e.g. what is relevant to measure or the research implications over time or space.
This paper provides an overview of how the research so far has defined sustainability, and how this definition has been used to guide which research areas. To this end, we carried out a systematic mapping study for selecting, classifying and analyzing relevant publications. In this study, we investigate which knowledge areas and which time scope of sustainability effects are mostly targeted in scientific research. Our analysis shows research trends and discusses gaps to be filled
Assessing the potential for knowledge-based development in transition countries. Bruegel Working Paper 2010/01, May 2010
This Working Paper by Bruegel Senior Fellow Reinhilde Veugelers examines the potential for a knowledge-based growth path in transition countries of central and eastern Europe, the Caucasus and Central Asia. The paper looks closely at how total-factor productivity, a residual growth factor commonly interpreted as reflecting technological progress, drives growth rates in these economies which exhibit a much lower GDP per capita compared to the EU15 or the United States. By analysing the prerequisites for knowledge-based growth, the author explains why transition countries are at a systemic disadvantage relative to the EU15, US and Japan and have limited potential for knowledge-based growth
Willman 1 - a probable dwarf galaxy with an irregular kinematic distribution
We investigate the kinematic properties and stellar population of the
Galactic satellite Willman 1 (Wil 1) by combining Keck/DEIMOS spectroscopy with
KPNO mosaic camera imaging. Wil 1 is an ultra-low luminosity Milky Way
companion. This object lies in a region of size-luminosity space (M_V ~ -2 mag,
d ~ 38 kpc, r_half ~ 20 pc) also occupied by the Galactic satellites Bo\"otes
II and Segue 1 and 2, but no other known old stellar system. We use kinematic
and color-magnitude criteria to identify 45 stars as possible members of Wil 1.
With a systemic velocity of v_helio = -12.8 +/- 1.0 km/s, Wil 1 stars have
velocities similar to those of foreground Milky Way stars. Informed by
Monte-Carlo simulations, we identify 5 of the 45 candidate member stars as
likely foreground contaminants. We confirm a significant spread in the
abundances of the likely Wil 1 red giant branch members ([Fe/H] = -1.73 +/-
0.12 and -2.65 +/- 0.12, [Ca/Fe] = -0.4 +/- 0.18 and +0.13 +/- 0.28). This
spread supports the scenario that Wil 1 is an ultra-low luminosity dwarf galaxy
rather than a star cluster. Wil 1's innermost stars move with radial velocities
offset by 8 km/s from its outer stars and have a velocity dispersion consistent
with 0 km/s, suggesting that Wil 1 may not be in dynamical equilibrium. The
combination of the foreground contamination and unusual kinematic distribution
make it difficult to robustly determine the dark matter mass of Wil 1. As a
result, X-ray or gamma-ray observations of Wil 1 that attempt to constrain
models of particle dark matter using an equilibrium mass model are strongly
affected by the systematics in the observations presented here. We conclude
that, despite the unusual features in the Wil 1 kinematic distribution,
evidence indicates that this object is, or at least once was, a dwarf galaxy.Comment: AJ accepted version. The primary improvements are a detailed
investigation of the membership probability (Section 3.4 and new Figures 6, 7
and 8) and the revised spectroscopic [Fe/H] and [Ca/Fe] measurements of the
two brightest member stars. Conclusions are unchanged from the submitted
versio
Resolving systemic financial crisis : policies and institutions
The authors analyze the role of institutions in resolving systemic banking crises for a broad sample of countries. Banking crises are fiscally costly, especially when policies like substantial liquidity support, explicit government guarantees on financial institutionsâ liabilities, and forbearance from prudential regulations are used. Higher fiscal outlays do not, however, accelerate the recovery from a crisis. Better institutionsâless corruption, improved law and order, legal system, and bureaucracyâdo. The authors find these results to be relatively robust to estimation techniques, including controlling for the effects of a poor institutional environment on the likelihood of financial crisis and the size of fiscal costs. Their results suggest that countries should use strict policies to resolve a crisis and use the crisis as an opportunity to implement medium-term structural reforms, which will also help avoid future systemic crises.Payment Systems&Infrastructure,Labor Policies,Fiscal&Monetary Policy,Financial Crisis Management&Restructuring,Banks&Banking Reform,Financial Crisis Management&Restructuring,Governance Indicators,National Governance,Banks&Banking Reform,Economic Conditions and Volatility
A New 95 GHz Methanol Maser Catalog: I. Data
The Purple Mountain Observatory 13.7 m radio telescope has been used to
search for 95 GHz (8--7A) class I methanol masers towards 1020
Bolocam Galactic Plane Survey (BGPS) sources, leading to 213 detections. We
have compared the line width of the methanol and HCO thermal emission in
all of the methanol detections and on that basis we find 205 of the 213
detections are very likely to be masers. This corresponds to an overall
detection rate of 95 GHz methanol masers towards our BGPS sample of 20%. Of the
205 detected masers 144 (70%) are new discoveries. Combining our results with
those of previous 95 GHz methanol masers searches, a total of four hundred and
eighty-one 95 GHz methanol masers are now known, we have compiled a catalog
listing the locations and properties of all known 95 GHz methanol masers.Comment: 18 pages, 7 figures, 8 tables, accepted for publication in ApJ
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