30,996 research outputs found
Spontaneous Analogy by Piggybacking on a Perceptual System
Most computational models of analogy assume they are given a delineated
source domain and often a specified target domain. These systems do not address
how analogs can be isolated from large domains and spontaneously retrieved from
long-term memory, a process we call spontaneous analogy. We present a system
that represents relational structures as feature bags. Using this
representation, our system leverages perceptual algorithms to automatically
create an ontology of relational structures and to efficiently retrieve analogs
for new relational structures from long-term memory. We provide a demonstration
of our approach that takes a set of unsegmented stories, constructs an ontology
of analogical schemas (corresponding to plot devices), and uses this ontology
to efficiently find analogs within new stories, yielding significant
time-savings over linear analog retrieval at a small accuracy cost.Comment: Proceedings of the 35th Meeting of the Cognitive Science Society,
201
Decoherence and determinism in a one-dimensional cloud-chamber model
The hypothesis by Sparenberg et al. (2013) that the particular linear tracks
appearing in the measurement of a spherically-emitting radioactive source in a
cloud chamber are determined by the (random) positions of atoms or molecules
inside the chamber is further explored in the framework of a recently
established one-dimensional model by Carlone et al. (2015). In this model,
meshes of localized spins 1/2 play the role of the cloud-chamber atoms and the
spherical wave is replaced by a linear superposition of two wave packets moving
from the origin to the left and to the right, evolving deterministically
according to the Schr\"odinger equation. We first revisit these results using a
time-dependent approach, where the wave packets impinge on a symmetric
two-sided detector. We discuss the evolution of the wave function in the
configuration space and stress the interest of a non-symmetric detector in a
quantum-measurement perspective. Next we use a time-independent approach to
study the scattering of a plane wave on a single-sided detector. Preliminary
results are obtained, analytically for the single-spin case and numerically for
up to 8 spins. They show that the spin-excitation probabilities are sometimes
very sensitive to the parameters of the model, which corroborates the idea that
the measurement result could be determined by the atom positions. The possible
origin of decoherence and entropy increase in future models is finally
discussed.Comment: Published version in Foundations of Physics. Text modified according
to referees' comment
Effective-range function methods for charged particle collisions
Different versions of the effective-range function method for charged
particle collisions are studied and compared. In addition, a novel derivation
of the standard effective-range function is presented from the analysis of
Coulomb wave functions in the complex plane of the energy. The recently
proposed effective-range function denoted as [Phys. Rev. C 96,
034601 (2017)] and an earlier variant [Hamilton et al., Nucl. Phys. B 60, 443
(1973)] are related to the standard function. The potential interest of
for the study of low-energy cross sections and weakly bound
states is discussed in the framework of the proton-proton collision.
The resonant state of the proton-proton collision is successfully computed from
the extrapolation of instead of the standard function. It is
shown that interpolating can lead to useful extrapolation to
negative energies, provided scattering data are known below one nuclear Rydberg
energy (12.5 keV for the proton-proton system). This property is due to the
connection between and the effective-range function by Hamilton
et al. that is discussed in detail. Nevertheless, such extrapolations to
negative energies should be used with caution because is not
analytic at zero energy. The expected analytic properties of the main functions
are verified in the complex energy plane by graphical color-based
representations.Comment: 17 pages, 11 figures, 46 references; typos fixe
Does Contributing Sequentially Increase the Level of Cooperation in Public Goods Games ? An Experimental Investigation
We run a series of experiments in which subjects have to choose their level of contribution to a pure public good. Our design differs from the standard public good game with respect to the decision procedure. Instead of deciding simultaneously in each round, subjects are randomly ordered in a sequence which differs from round to round. We compare sessions in which subjects can observe the exact contributions from earlier decisions ("Sequential treatment with Information") to sessions in which subjects decide sequentially but cannot observe earlier contributions ("Sequential treatment without information"). Furthermore, we investigate the effect of group size on aggregate contributions. Our result indicate that contributing sequentially increases the level of contribution to the public good when subjects are informed about the contribution levels of lower ranked subjects. Moreover, we observe that earlier players in the sequence try to influence positively the contributions of subsequent decision makers in the sequence, by making a large contribution. Such behaviour is motivated by the belief that subsequent players will reciprocate by also making a large contribution.
Reasoning about Independence in Probabilistic Models of Relational Data
We extend the theory of d-separation to cases in which data instances are not
independent and identically distributed. We show that applying the rules of
d-separation directly to the structure of probabilistic models of relational
data inaccurately infers conditional independence. We introduce relational
d-separation, a theory for deriving conditional independence facts from
relational models. We provide a new representation, the abstract ground graph,
that enables a sound, complete, and computationally efficient method for
answering d-separation queries about relational models, and we present
empirical results that demonstrate effectiveness.Comment: 61 pages, substantial revisions to formalisms, theory, and related
wor
Discrete conservation properties for shallow water flows using mixed mimetic spectral elements
A mixed mimetic spectral element method is applied to solve the rotating
shallow water equations. The mixed method uses the recently developed spectral
element histopolation functions, which exactly satisfy the fundamental theorem
of calculus with respect to the standard Lagrange basis functions in one
dimension. These are used to construct tensor product solution spaces which
satisfy the generalized Stokes theorem, as well as the annihilation of the
gradient operator by the curl and the curl by the divergence. This allows for
the exact conservation of first order moments (mass, vorticity), as well as
quadratic moments (energy, potential enstrophy), subject to the truncation
error of the time stepping scheme. The continuity equation is solved in the
strong form, such that mass conservation holds point wise, while the momentum
equation is solved in the weak form such that vorticity is globally conserved.
While mass, vorticity and energy conservation hold for any quadrature rule,
potential enstrophy conservation is dependent on exact spatial integration. The
method possesses a weak form statement of geostrophic balance due to the
compatible nature of the solution spaces and arbitrarily high order spatial
error convergence
Does work pay in France ? Monetary incentives and the guaranteed minimum income
Most welfare programs generate high marginal tax rates on labor income. This paper uses a representative sample of individuals on France's main welfare program (the Revenu Minimum d'Insertion, or RMI) to estimate monetary gains to employment for welfare recipients. This is based on the distribution of potential monthly earnings faced by each individual, as inferred from the distribution of observed wages and working time. Taking account of the welfare earnings top-up program (intéressement), we find that gains are almost always positive, but that their amount is very low, especially for single mothers. Intéressement is found to have a small impact, because of its provisional nature. Gains are positively related to the probability that a welfare recipient in 1996 will be observed in employment in 1998. Using a simple structural model, we interpret this as a labor supply effect.Welfare, labor earnings, transfers, tax-system.
On the amplitudes for the CP-conserving rare decay modes
The amplitudes for the rare decay modes and
are studied with the aim of obtaining predictions for
them, such as to enable the possibility to search for violations of
lepton-flavour universality in the kaon sector. The issue is first addressed
from the perspective of the low-energy expansion, and a two-loop representation
of the corresponding form factors is constructed, leaving as unknown quantities
their values and slopes at vanishing momentum transfer. In a second step a
phenomenological determination of the latter is proposed. It consists of the
contribution of the resonant two-pion state in the wave, and of the leading
short-distance contribution determined by the operator-product expansion. The
interpolation between the two energy regimes is described by an infinite tower
of zero-width resonances matching the QCD short-distance behaviour. Finally,
perspectives for future improvements in the theoretical understanding of these
amplitudes are discussed.Comment: 49 pages, 11 figures, matches the published versio
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