Reports de recerca
http://hdl.handle.net/2117/3229
20150903T00:31:45ZA note on symplectic and Poisson linearization of semisimple Lie algebra actions
http://hdl.handle.net/2117/26960
A note on symplectic and Poisson linearization of semisimple Lie algebra actions
Miranda Galcerán, Eva
In this note we prove that an analytic symplectic action of a semisimple Lie algebra can be locally linearized in Darboux coordinates. This result yields simultaneous analytic linearization for Hamiltonian vector fields in a neighbourhood of a common zero. We also provide an example of smooth nonlinearizable Hamiltonian action with semisimple linear part. The smooth analogue only holds if the semisimple Lie algebra is of compact type. An analytic equivariant bDarboux theorem for bPoisson manifolds and an analytic equivariant Weinstein splitting theorem for general Poisson manifolds are also obtained in the Poisson setting
20150301T00:00:00ZActionangle variables and a KAM theorem for bPoisson manifolds
http://hdl.handle.net/2117/26390
Actionangle variables and a KAM theorem for bPoisson manifolds
Kiesenhofer, Anna; Miranda Galcerán, Eva; Scott, Geoffrey
In this article we prove an actionangle theorem for bintegrable systems on bPoisson manifolds improving the actionangle theorem contained in [LMV11] for general Poisson manifolds in this setting. As an application, we prove a KAMtype theorem for bPoisson manifolds.
20150201T00:00:00ZXiao's conjuecture for general fibred surfaces
http://hdl.handle.net/2117/24999
Xiao's conjuecture for general fibred surfaces
Barja Yáñez, Miguel Ángel; González Alonso, Víctor; Naranjo del Val, Joan Carles
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.
Prerpint
20140110T00:00:00ZStability and singularities of relative hypersurfaces
http://hdl.handle.net/2117/24998
Stability and singularities of relative hypersurfaces
Barja Yáñez, Miguel Ángel; Stoppino, Lidia
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.
20140730T00:00:00ZAlgebraic description of Jacobians isogeneous to certain Prym varieties with polarization (1,2)
http://hdl.handle.net/2117/24994
Algebraic description of Jacobians isogeneous to certain Prym varieties with polarization (1,2)
Fedorov, Yuri; Enolski, Viktor Z.
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 examples
20141101T00:00:00ZRigidity of Poisson Lie group actions
http://hdl.handle.net/2117/24632
Rigidity of Poisson Lie group actions
Miranda Galcerán, Eva
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}).
20140101T00:00:00ZLyubeznik numbers of local rings and linear strands of graded ideals
http://hdl.handle.net/2117/24185
Lyubeznik numbers of local rings and linear strands of graded ideals
Álvarez Montaner, Josep; Yanagawa, Kohji
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 field
20140801T00:00:00ZA methodology for obtaining asymptotic estimates for the exponentially small splitting of separatrices to whiskered tori with quadratic frequencies
http://hdl.handle.net/2117/24155
A methodology for obtaining asymptotic estimates for the exponentially small splitting of separatrices to whiskered tori with quadratic frequencies
Delshams Valdés, Amadeu; Gonchenko, Marina; Gutiérrez Serrés, Pere
20140701T00:00:00ZContinuation of the exponentially small lower bounds for the splitting of separatrices to a whiskered torus with silver ratio
http://hdl.handle.net/2117/24138
Continuation of the exponentially small lower bounds for the splitting of separatrices to a whiskered torus with silver ratio
Delshams Valdés, Amadeu; Gonchenko, Marina; Gutiérrez Serrés, Pere
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 $\varepsilon
20140901T00:00:00ZCàlcul numèric. Manual de pràctiques
http://hdl.handle.net/2117/24072
Càlcul numèric. Manual de pràctiques
Lázaro Ochoa, José Tomás; Ollé Torner, Mercè; Pacha Andújar, Juan Ramón
20140701T00:00:00Z