DSpace Collection:
http://hdl.handle.net/2117/3919
20141221T04:20:29ZTechnical note: on the logical independence in two axiomatic characterizations of coalitional multinomial probabilistic values
http://hdl.handle.net/2117/25112
Title: Technical note: on the logical independence in two axiomatic characterizations of coalitional multinomial probabilistic values
Authors: Carreras Escobar, Francisco; Puente del Campo, María Albina20141219T16:33:39ZXiao's conjuecture for general fibred surfaces
http://hdl.handle.net/2117/24999
Title: Xiao's conjuecture for general fibred surfaces
Authors: Barja Yáñez, Miguel Ángel; González Alonso, Víctor; Naranjo del Val, Joan Carles
Abstract: We prove that the genus g, the relative irregularity q_f and the Clifford index c_f of a nonisotrivial fibration
f satisfy the inequality q_f=gc_f. This gives in particular a proof of Xiao’s conjecture for
fibrations whose general fibres have maximal Clifford index.
Description: Prerpint20141211T12:05:29ZStability and singularities of relative hypersurfaces
http://hdl.handle.net/2117/24998
Title: Stability and singularities of relative hypersurfaces
Authors: Barja Yáñez, Miguel Ángel; Stoppino, Lidia
Abstract: We study relative hypersurfaces, and prove an instability condition for the fibres. This
is the starting point for an investigation of the geometry of effective divisors on relative
projective bundles.20141211T12:01:17ZAlgebraic description of Jacobians isogeneous to certain Prym varieties with polarization (1,2)
http://hdl.handle.net/2117/24994
Title: Algebraic description of Jacobians isogeneous to certain Prym varieties with polarization (1,2)
Authors: Fedorov, Yuri; Enolski, Viktor Z.
Abstract: For a class of nonhyperelliptic genus 3 curves C which are 2fold coverings of elliptic curves E, we give an explicit algebraic description of all birationally nonequivalent genus 2 curves whose Jacobians are degree 2 isogeneous to the Prym varieties associated to such coverings. Our description is based on previous studies of Prym varieties with polarization (1,2) in connection with separation of variables in a series of classical and new algebraic integrable systems linearized on such varieties.
We also consider some special cases of the covering C > E, in particular, when the corresponding Prym varieties contain pairs of elliptic curves and the Jacobian of C is isogeneous (but not isomorphic) to the product of 3 different elliptic curves.
Our description is accompanied with explicit numerical examples20141211T08:09:29ZRigidity of Poisson Lie group actions
http://hdl.handle.net/2117/24632
Title: Rigidity of Poisson Lie group actions
Authors: Miranda Galcerán, Eva
Abstract: n this paper we prove that close infinitesimal momentum maps associated to Poisson Lie actions are equivalent under some mild assumptions. We also obtain rigidity theorems for actual momentum maps (when the acting Lie group G is endowed with an arbitrary Poisson structure) combining a rigidity result for canonical Hamiltonian actions (\cite{MMZ}) and a linearization theorem(\cite{GW}). These results have applications to quantization of symmetries since these infinitesimal momentum maps appear as the classical limit of quantum momentum maps (\cite{BEN}).20141110T12:51:24ZExtended version. Occurrence of solar flares viewed with GPS: statistics and fractal nature
http://hdl.handle.net/2117/24607
Title: Extended version. Occurrence of solar flares viewed with GPS: statistics and fractal nature
Authors: Monte Moreno, Enrique; Hernández Pajares, Manuel
Abstract: In this paper we describe the statistical properties of the EUV solar flux sudden variation. The solar flux variation is modeled as a time series characterized by the subsolar VTEC (Vertical Total Electron Content) doubledifference in time, computed with dual frequency GNSS (Global Navigation Satellite System) measurements in the daylight hemisphere. By assuming a sudden overionization pattern of solar origin, during the last solar cycle, we propose a model that explains it's characteristics, and the forecasting limitations. The two defining characteristics of this time series, is an extreme variability (i.e.\ in a solar cycle one can find events at $400 \sigma$ from the mean value) and a temporal correlation that is independent of the time scale. We give a characterization of a model that explains the empirical results, and properties such as, a) the persistence and presence of bursts of solar flares, b) their long tail peak values of the solar flux variation. We show that the solar flux variation time series can be characterized by a fractional Brownian model for the long term dependence, and a powerlaw distribution for the extreme values that appear in the time series.
Description: Extended version of the paper20141107T14:46:29ZLyubeznik numbers of local rings and linear strands of graded ideals
http://hdl.handle.net/2117/24185
Title: Lyubeznik numbers of local rings and linear strands of graded ideals
Authors: Álvarez Montaner, Josep; Yanagawa, Kohji
Abstract: n this work we intro duce a new set of invariants asso ciated to the linear
strands of a minimal free resolution of a
Z
graded ideal
I
R
=

[
x
1
;:::;x
n
]
. We
also prove that these invariants satisfy some prop erties analogous to those of Lyub eznik
numb ers of lo cal rings. In particular, they satisfy a consecutiveness prop erty that we
prove rst for Lyub eznik numb ers. For the case of squarefree monomial ideals we get
more insight on the relation b etween Lyub eznik numb ers and the linear strands of their
asso ciated Alexander dual ideals. Finally, we prove that Lyub eznik numb ers of Stanley
Reisner rings are not only an algebraic invariant but also a top ological invariant, meaning
that they dep end on the homeomorphic class of the geometric realization of the asso ciated
simplicial complex and the characteristic of the base field20140930T09:46:24ZA methodology for obtaining asymptotic estimates for the exponentially small splitting of separatrices to whiskered tori with quadratic frequencies
http://hdl.handle.net/2117/24155
Title: A methodology for obtaining asymptotic estimates for the exponentially small splitting of separatrices to whiskered tori with quadratic frequencies
Authors: Delshams Valdés, Amadeu; Gonchenko, Marina; Gutiérrez Serrés, Pere20140925T08:12:02ZContinuation of the exponentially small lower bounds for the splitting of separatrices to a whiskered torus with silver ratio
http://hdl.handle.net/2117/24138
Title: Continuation of the exponentially small lower bounds for the splitting of separatrices to a whiskered torus with silver ratio
Authors: Delshams Valdés, Amadeu; Gonchenko, Marina; Gutiérrez Serrés, Pere
Abstract: We study the exponentially small splitting of invariant manifolds of whiskered (hyperbolic) tori with two fast
frequencies in nearlyintegrable Hamiltonian systems whose hyperbolic part is given by a pendulum. We consider a torus whose frequency ratio is the silver number $\Omega=\sqrt21$. We show that the oincareMelnikov method can be applied to establish the existence of 4 transverse homoclinic orbits to the whiskered torus, and provide
asymptotic estimates for the tranversality of the splitting whose dependence on the perturbation parameter $\varepsilon$ satisffies a periodicity property. We also prove the continuation of the transversality of the homoclinic orbits for all the sufficiently small values of $\varepsilon20140923T09:33:01ZCàlcul numèric. Manual de pràctiques
http://hdl.handle.net/2117/24072
Title: Càlcul numèric. Manual de pràctiques
Authors: Lázaro Ochoa, José Tomás; Ollé Torner, Mercè; Pacha Andújar, Juan Ramón20140917T07:45:15ZDecomposition spaces, incidence algebras and Möbius inversion
http://hdl.handle.net/2117/23130
Title: Decomposition spaces, incidence algebras and Möbius inversion
Authors: Gálvez Carrillo, Maria Immaculada; Kock, Joachim; Tonks, Andrew20140603T08:45:51ZConsolidated characterisation of an ionospheric indicator for the definition of EGNOS Ionospheric Conditions
http://hdl.handle.net/2117/23040
Title: Consolidated characterisation of an ionospheric indicator for the definition of EGNOS Ionospheric Conditions
Authors: Juan Zornoza, José Miguel; Sanz Subirana, Jaume20140523T18:17:49ZFeasibility analysis of a methodology to estimate hourly DCBs for Feared Events Characterization
http://hdl.handle.net/2117/23039
Title: Feasibility analysis of a methodology to estimate hourly DCBs for Feared Events Characterization
Authors: Juan Zornoza, José Miguel; Sanz Subirana, Jaume
Abstract: Analysis of Hardware Biases Feared Events20140523T17:48:23ZHermann Weyl entre nosaltres. El curs de 1922 i algunes de les seves repercussions
http://hdl.handle.net/2117/22995
Title: Hermann Weyl entre nosaltres. El curs de 1922 i algunes de les seves repercussions
Authors: Roca Rosell, Antoni Maria Claret
Abstract: El 30 de març de 1921 Esteve Terradas escriví Hermann Weyl a Zúric convidantlo
perquè vingués a Barcelona a donar un curs “de 8 lliçons”1. Es tractava molt
probablement del primer contacte que s’establia entre ambdós. Terradas explica que “el
nostre govern local”, és a dir, la Mancomunitat de Catalunya, organitza conferències a
càrrec de professors destacats. Li menciona els primers físicomatemàtics que han
participat, Tullio LeviCivita i Jacques Hadamard, tots dos en el primer trimestre de
1921. També li diu que té la intenció de fer venir Einstein.20140515T09:07:35ZExponentially small lower bounds for the splitting of separatrices to whiskered tori with frequencies of constant type
http://hdl.handle.net/2117/22687
Title: Exponentially small lower bounds for the splitting of separatrices to whiskered tori with frequencies of constant type
Authors: Delshams Valdés, Amadeu; Gonchenko, Marina; Gutiérrez Serrés, Pere
Abstract: We study the splitting of invariant manifolds of whiskered tori with two frequencies in nearlyintegrable
Hamiltonian systems, such that the hyperbolic part is given by a pendulum. We
consider a 2dimensional torus with a fast frequency vector $\omega/v\epsilon$, with $\epsilon=(1,\Omega)$ where $\Omega$ is an irrational number of constant type, i.e. a number whose continued fraction has bounded
entries. Applying the Poincar´e–Melnikov method, we find exponentially small lower bounds for
the maximal splitting distance between the stable and unstable invariant manifolds associated to
the invariant torus, and we show that these bounds depend strongly on the arithmetic properties
of the frequencies.20140424T09:32:24Z