670 research outputs found
Constructions in R[x_1, ..., x_n]. Applications to K-Theory
A classical result in K-Theory about polynomial rings like the Quillen-Suslin
theorem admits an algorithmic approach when the ring of coefficients has some
computational properties, associated with Gröbner bases. There are several
algorithms when we work in \K[\x], \K a field. In this paper we compute a
free basis of a finitely generated projective module over R[\x], a
principal ideal domain with additional properties, test the freeness for
projective modules over D[\x], with a Dedekind domain like
\Zset[\sqrt{-5}] and for the one variable case compute a free basis if there
exists any.DGICYT PB97-0723, Junta de Andalucía FQM-21
La transición de la vela al vapor en la flota mercante española: cambio técnico y estrategia empresarial
Editada en la Universidad Carlos IIIEn España los pocos trabajos que analizan la transición de la vela al vapor
en la flota mercante española lo hacen en términos de fracaso y decadencia. Sin
embargo, esa impresión no concuerda bien con las magnitudes cuantitativas
internacionales disponibles que sitúan a la flota mercante española como una
de las primeras en cuanto al grado de difusión del buque de vapor en las tres
últimas décadas del siglo XIX. El objetivo de este artículo es analizar el proceso
de cambio técnico, institucional y organizativo de la marina mercante española
durante la segunda mitad del siglo XIX y la estrategia empresarial de los
navieros españoles ante el mismo.The few works which talk about the transition from sail to steam in the
Spanish merchant marine, analyze it in terms of decadence and failure. But
these imptessions do not pair with an analysis of the Spanish fleet from an
International perspective: it was among the pionneers, together with Great
Britain, to complete the technological modernization of its ships. The objective
of this paper is to describe and explain the process of technical diffusion, the
changes in the institutional framework, and the business strategy of Spanish
shipowners in this context.Publicad
Bases for Projective modules in An(k)
Let be the Weyl algebra, with a field of characteristic zero.
It is known that every projective finitely generated left module is free
or isomorphic to a left ideal. Let be a left submodule of a free
module. In this paper we give an algorithm to compute the projective
dimension of . If is projective and \rk(M) \ge 2 we give a
procedure to find a basis.Ministerio de Ciencia y Tecnología (Spain) BFM2001-3164, FQM-813Junta de Andalucía FQM-81
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