5,340 research outputs found

    The Economics of Cultural Formation of Preferences

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    This paper introduces a generalized representation of the formation of continuous preferences (which can reflect different intensities). The preference intensity that a child adopts is formed as the collective outcome of all role models for preference intensities - which are derived from the socioeconomic actions of adults - that it socially learns from. We then show how the adopted preference intensities induce preferences over socioeconomic choices. Finally, this cultural formation of preferences process is endogenized as resulting out of optimal parental socialization decisions. This framework thus endogenously determines the intergenerational evolution of preference intensities and the induced preferences.Socialization, Preference Evolution, Endogenous Preferences, Cultural transmission

    Cultural Formation of Preferences and Assimilation of Cultural Groups

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    Based on the cultural formation of continuous preferences framework of Pichler (IMW Working Paper No. 431, 2010), this paper analyzes the evolution of preferences and behavior in a two cultural groups setting. We show that the qualitative dynamic properties depend crucially on what parents perceive as the optimal preferences for their children to adopt. Under inter– generationally fixed optimal preferences, the preferences of the cultural groups will always stay distinct. If the optimal preferences coincide with those derived from the representative group behavior, then a multitude of convergence path types can realize. These contain both an inter–generational assimilation process toward the same preference point, as well as inter–generational dissimilation.Continuous Preferences, Assimilation, Cultural Groups, Endogenous Preferences, Preference Evolution, Socialization

    Provenance Circuits for Trees and Treelike Instances (Extended Version)

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    Query evaluation in monadic second-order logic (MSO) is tractable on trees and treelike instances, even though it is hard for arbitrary instances. This tractability result has been extended to several tasks related to query evaluation, such as counting query results [3] or performing query evaluation on probabilistic trees [10]. These are two examples of the more general problem of computing augmented query output, that is referred to as provenance. This article presents a provenance framework for trees and treelike instances, by describing a linear-time construction of a circuit provenance representation for MSO queries. We show how this provenance can be connected to the usual definitions of semiring provenance on relational instances [20], even though we compute it in an unusual way, using tree automata; we do so via intrinsic definitions of provenance for general semirings, independent of the operational details of query evaluation. We show applications of this provenance to capture existing counting and probabilistic results on trees and treelike instances, and give novel consequences for probability evaluation.Comment: 48 pages. Presented at ICALP'1

    Tensor networks for Lattice Gauge Theories and Atomic Quantum Simulation

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    We show that gauge invariant quantum link models, Abelian and non-Abelian, can be exactly described in terms of tensor networks states. Quantum link models represent an ideal bridge between high-energy to cold atom physics, as they can be used in cold-atoms in optical lattices to study lattice gauge theories. In this framework, we characterize the phase diagram of a (1+1)-d quantum link version of the Schwinger model in an external classical background electric field: the quantum phase transition from a charge and parity ordered phase with non-zero electric flux to a disordered one with a net zero electric flux configuration is described by the Ising universality class.Comment: 9 pages, 9 figures. Published versio

    Transition from a Tomonaga-Luttinger liquid to a Fermi liquid in potassium intercalated bundles of single wall carbon nanotubes

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    We report on the first direct observation of a transition from a Tomonaga-Luttinger liquid to a Fermi liquid behavior in potassium intercalated mats of single wall carbon nanotubes (SWCNT). Using high resolution photoemission spectroscopy an analysis of the spectral shape near the Fermi level reveals a Tomonaga-Luttinger liquid power law scaling in the density of states for the pristine sample and for low dopant concentration. As soon as the doping is high enough to fill bands of the semiconducting tubes a distinct transition to a bundle of only metallic SWCNT with a scaling behavior of a normal Fermi liquid occurs. This can be explained by a strong screening of the Coulomb interaction between charge carriers and/or an increased hopping matrix element between the tubes.Comment: 5 pages, 4 figure

    Thermal vs. Entanglement Entropy: A Measurement Protocol for Fermionic Atoms with a Quantum Gas Microscope

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    We show how to measure the order-two Renyi entropy of many-body states of spinful fermionic atoms in an optical lattice in equilibrium and non-equilibrium situations. The proposed scheme relies on the possibility to produce and couple two copies of the state under investigation, and to measure the occupation number in a site- and spin-resolved manner, e.g. with a quantum gas microscope. Such a protocol opens the possibility to measure entanglement and test a number of theoretical predictions, such as area laws and their corrections. As an illustration we discuss the interplay between thermal and entanglement entropy for a one dimensional Fermi-Hubbard model at finite temperature, and its possible measurement in an experiment using the present scheme

    The tractability frontier of well-designed SPARQL queries

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    We study the complexity of query evaluation of SPARQL queries. We focus on the fundamental fragment of well-designed SPARQL restricted to the AND, OPTIONAL and UNION operators. Our main result is a structural characterisation of the classes of well-designed queries that can be evaluated in polynomial time. In particular, we introduce a new notion of width called domination width, which relies on the well-known notion of treewidth. We show that, under some complexity theoretic assumptions, the classes of well-designed queries that can be evaluated in polynomial time are precisely those of bounded domination width

    Incidence of the Tomonaga-Luttinger liquid state on the NMR spin lattice relaxation in Carbon Nanotubes

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    We report 13C nuclear magnetic resonance measurements on single wall carbon nanotube (SWCNT) bundles. The temperature dependence of the nuclear spin-lattice relaxation rate, 1/T1, exhibits a power-law variation, as expected for a Tomonage-Luttinger liquid (TLL). The observed exponent is smaller than that expected for the two band TLL model. A departure from the power law is observed only at low T, where thermal and electronic Zeeman energy merge. Extrapolation to zero magnetic field indicates gapless spin excitations. The wide T range on which power-law behavior is observed suggests that SWCNT is so far the best realization of a one-dimensional quantum metal.Comment: 5 pages, 4 figure
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