239 research outputs found
Tops-Only Domains
In this paper we consider the standard voting model with a finite set of alternatives A and n voters and address the following question : what are the characteristics of domains D that induce the property that every strategy-proof social choice function f : Dn -> A satisfying unanimity, has the tops-only property? We first impose a minimal richness condition which ensures that for every alternative a, there exists an admissible ordering where a is maximal. We identify conditions on D that are sufficient for strategy-proofness and unanimity to imply tops onlyness in the general case of n voters and in the special case, n = 2. We provide an algorithm for constructing tops-only domains from connected graphs with elements of A as nodes. We provide several applications of our results. Finally, we relax the minimal richness assumption and partially extend our results.Voting, social choice, tops-only domain
Flaw Selection Strategies for Partial-Order Planning
Several recent studies have compared the relative efficiency of alternative
flaw selection strategies for partial-order causal link (POCL) planning. We
review this literature, and present new experimental results that generalize
the earlier work and explain some of the discrepancies in it. In particular, we
describe the Least-Cost Flaw Repair (LCFR) strategy developed and analyzed by
Joslin and Pollack (1994), and compare it with other strategies, including
Gerevini and Schubert's (1996) ZLIFO strategy. LCFR and ZLIFO make very
different, and apparently conflicting claims about the most effective way to
reduce search-space size in POCL planning. We resolve this conflict, arguing
that much of the benefit that Gerevini and Schubert ascribe to the LIFO
component of their ZLIFO strategy is better attributed to other causes. We show
that for many problems, a strategy that combines least-cost flaw selection with
the delay of separable threats will be effective in reducing search-space size,
and will do so without excessive computational overhead. Although such a
strategy thus provides a good default, we also show that certain domain
characteristics may reduce its effectiveness.Comment: See http://www.jair.org/ for an online appendix and other files
accompanying this articl
Modules for Experiments in Stellar Astrophysics (MESA)
Stellar physics and evolution calculations enable a broad range of research
in astrophysics. Modules for Experiments in Stellar Astrophysics (MESA) is a
suite of open source libraries for a wide range of applications in
computational stellar astrophysics. A newly designed 1-D stellar evolution
module, MESA star, combines many of the numerical and physics modules for
simulations of a wide range of stellar evolution scenarios ranging from
very-low mass to massive stars, including advanced evolutionary phases. MESA
star solves the fully coupled structure and composition equations
simultaneously. It uses adaptive mesh refinement and sophisticated timestep
controls, and supports shared memory parallelism based on OpenMP. Independently
usable modules provide equation of state, opacity, nuclear reaction rates, and
atmosphere boundary conditions. Each module is constructed as a separate
Fortran 95 library with its own public interface. Examples include comparisons
to other codes and show evolutionary tracks of very low mass stars, brown
dwarfs, and gas giant planets; the complete evolution of a 1 Msun star from the
pre-main sequence to a cooling white dwarf; the Solar sound speed profile; the
evolution of intermediate mass stars through the thermal pulses on the He-shell
burning AGB phase; the interior structure of slowly pulsating B Stars and Beta
Cepheids; evolutionary tracks of massive stars from the pre-main sequence to
the onset of core collapse; stars undergoing Roche lobe overflow; and accretion
onto a neutron star. Instructions for downloading and installing MESA can be
found on the project web site (http://mesa.sourceforge.net/).Comment: 110 pages, 39 figures; submitted to ApJS; visit the MESA website at
http://mesa.sourceforge.ne
Beyond the simple Proximity Force Approximation: geometrical effects on the non-retarded Casimir interaction
We study the geometrical corrections to the simple Proximity Force
Approximation for the non-retarded Casimir force. We present analytical results
for the force between objects of various shapes and substrates, and between
pairs of objects. We compare the results to those from more exact numerical
calculations. We treat spheres, spheroids, cylinders, cubes, cones, and wings;
the analytical PFA results together with the geometrical correction factors are
summarized in a table.Comment: 18 pages, 19 figures, 1 tabl
Beyond the simple Proximity Force Approximation: geometrical effects on the non-retarded Casimir interaction
We study the geometrical corrections to the simple Proximity Force
Approximation for the non-retarded Casimir force. We present analytical results
for the force between objects of various shapes and substrates, and between
pairs of objects. We compare the results to those from more exact numerical
calculations. We treat spheres, spheroids, cylinders, cubes, cones, and wings;
the analytical PFA results together with the geometrical correction factors are
summarized in a table.Comment: 18 pages, 19 figures, 1 tabl
A hybrid algorithm for Bayesian network structure learning with application to multi-label learning
We present a novel hybrid algorithm for Bayesian network structure learning,
called H2PC. It first reconstructs the skeleton of a Bayesian network and then
performs a Bayesian-scoring greedy hill-climbing search to orient the edges.
The algorithm is based on divide-and-conquer constraint-based subroutines to
learn the local structure around a target variable. We conduct two series of
experimental comparisons of H2PC against Max-Min Hill-Climbing (MMHC), which is
currently the most powerful state-of-the-art algorithm for Bayesian network
structure learning. First, we use eight well-known Bayesian network benchmarks
with various data sizes to assess the quality of the learned structure returned
by the algorithms. Our extensive experiments show that H2PC outperforms MMHC in
terms of goodness of fit to new data and quality of the network structure with
respect to the true dependence structure of the data. Second, we investigate
H2PC's ability to solve the multi-label learning problem. We provide
theoretical results to characterize and identify graphically the so-called
minimal label powersets that appear as irreducible factors in the joint
distribution under the faithfulness condition. The multi-label learning problem
is then decomposed into a series of multi-class classification problems, where
each multi-class variable encodes a label powerset. H2PC is shown to compare
favorably to MMHC in terms of global classification accuracy over ten
multi-label data sets covering different application domains. Overall, our
experiments support the conclusions that local structural learning with H2PC in
the form of local neighborhood induction is a theoretically well-motivated and
empirically effective learning framework that is well suited to multi-label
learning. The source code (in R) of H2PC as well as all data sets used for the
empirical tests are publicly available.Comment: arXiv admin note: text overlap with arXiv:1101.5184 by other author
Disclosure rules and declared essential patents
Many standard setting organizations (SSOs) require participants to disclose patents that might be infringed by implementing a proposed standard, and commit to license their “essential” patents on terms that are fair, reasonable and non-discriminatory (FRAND). Data from SSO intellectual property disclosures have been used in academic studies to provide a window into the standard setting process, and in legal proceedings to assess the relative contribution of different parties to a standard. We describe the disclosure process, discuss the link between SSO rules and patent-holder incentives, and analyze disclosure practices using a novel dataset constructed from the disclosure archives of thirteen major SSOs. Our empirical results suggest that subtle differences in SSO policies influence which patents are disclosed, the terms of licensing commitments, and ultimately long-run citation and litigation rates for the underlying patents. Thus, while policy debates sometimes characterize SSOs as a relatively homogeneous set of institutions, our results point in the opposite direction – towards the importance of recognizing heterogeneity in SSO policies and practices
The Dutch deposit of electronic publications (DNEP) - 1995-2000
In 1993 the Internet took off with the introduction of HTML and the first
browser (Mosaic1). Two years later, in 1995, the Koninklijke Bibliotheek
decided to start a series of experiments and projects which would lead to a
deposit system for Dutch Electronic Publications. In the same year the
Koninklijke Bibliotheek made a policy decision to include electronic material
into its deposit.
That marked the start of the Dutch Deposit for Electronic Publications
(DNEP2). Both as an operational service and at the same time as a test-bed for
research into digital archiving.
The Koninklijke Bibliotheek has a staff of 254.5 FTE3. The ICT-department
has 15 FTE (about 6%).The ICT-department is responsible for the systems
management of the operational systems, for the support of the end-users and
for research and development. Apart from the R&D done in the ICTdepartment
the Koninklijke Bibliotheek also has a department of library
research (see the website4 of the Koninklijke Bibliotheek for more information).
In the first few years a lot of experiments were done. Various hardware and
software was tested and research was done on issues such as metadata, the
number of electronic publications available, how to process them in the
library etc. At the end of 1998 the Koninklijke Bibliotheek decided that the
time was ripe to make the next step. This was the implementation of the
DNEP on a large scale and as part of the normal workflow inside the library
departments
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