18,215 research outputs found
Elimination of quotients in various localisations of premodels into models
The contribution of this article is quadruple. It (1) unifies various schemes
of premodels/models including situations such as presheaves/sheaves,
sheaves/flabby sheaves, prespectra/-spectra, simplicial topological
spaces/(complete) Segal spaces, pre-localised rings/localised rings, functors
in categories/strong stacks and, to some extent, functors from a limit sketch
to a model category versus the homotopical models for the limit sketch; (2)
provides a general construction from the premodels to the models; (3) proposes
technics that allows one to assess the nature of the universal properties
associated with this construction; (4) shows that the obtained localisation
admits a particular presentation, which organises the structural and relational
information into bundles of data. This presentation is obtained via a process
called an elimination of quotients and its aim is to facilitate the handling of
the relational information appearing in the construction of higher dimensional
objects such as weak -categories, weak -groupoids and
higher moduli stacks.Comment: The text is the same as in v6; this version contains corrections to
the published MDPI paper, the main reason for this change is that the diagram
of Proposition 3.1 was meant to be a 3 dimensional diagram (while only the
front face appeared in the published paper). The wording of some sentences
and the diagram of Example 6.42 are changed accordingly. A typo in the table
of Ex. 6.42 is correcte
Where is the Cuban economy heading ?
This article is the introduction of an issue (to be published) of the U.S. review International Journal of Political Economy on the Cuban economy, and coordinated by RĂ©my Herrera. It deals with the progresses, but also with the deficiencies, of the Cuban revolution in the economic field, until the recent de-dollarization. It underlines its economic challenges at the beginning of the XXIst century, as well as its internal forces and its external opportunities facing these challenges.Development, socialism, revolution, growth, de-dollarization, social expenditure.
The Effect of Spillovers and Congestion on the Segregative Properties of Endogenous Jurisdiction Structure Formation
This paper analyzes the effect of spillovers and congestion of local public goods on the segregative properties of endogenous formation of jurisdiction. Households living in the same place form a jurisdiction and produce a local public good, that creates positive spillovers in other jurisdictions and suffers from congestion. In every jurisdiction, the production of the local public good is financed through a local tax on household's wealth. Local wealth tax rates are democratically determined in all jurisdictions. Households also consume housing in their jurisdiction. Any household is free to leave its jurisdiction for another one that would increase its utility. A necessary and sufficient condition to have every stable jurisdiction structure segregated by wealth, for a large class of congestion measure and any spillovers coefficient structure, is identified: the public good must be a gross substitute or a gross complement to the private good and the housing.Jurisdictions, Segregation, Spillovers, Congestion
The effect of spillovers and congestion on the segregative properties of endogenous jurisdictions formation*
This paper analyzes the eect of spillovers and congestion of local public services on the segregative properties of endogenous formation of jurisdictions. Households choosing to live at the same place form a jurisdiction whose aim is to produce congested local public services, that can create positive spillovers to other jurisdictions. In every jurisdiction, the production of the local public services is nanced through a local tax based on households' wealth. Local wealth tax rates are democratically determined in all jurisdictions. Households also consume housing in their jurisdiction. Any household is free to leave its jurisdiction for another one that would increase its utility. A necessary and sucient condition to have every stable jurisdictions structure segregated by wealth, for a large class of congestion measures and any spillovers coecients structure, is identied: the public services must be either a gross substitute or a gross complement to the private good and the housing.Jurisdictions; Segregation; Spillovers; Congestion JEL Classication: C78; D02; H73; R13
Magnetic and electric properties of quantum vacuum
In this report we show that vacuum is a nonlinear optical medium and we
discuss what are the optical phenomena that should exist in the framework of
the standard model of particle physics. We pay special attention to the low
energy limit. The predicted effects for photons of energy smaller than the
electron rest mass are of such a level that none has been observed
experimentally yet. Progresses in field sources and related techniques seem to
indicate that in few years vacuum nonlinear optics will be accessible to human
investigation.Comment: Reports on Progress in Physics (2013) in pres
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