1,720,963 research outputs found
Existence of periodic solutions of Hamiltonian systems with potential indefinite in sign.
No full textOn the Euler equation for minimal geodesics on Riemannian manifolds having discontinuous metrics
No full textWe provide a qualitative description of curves minimizing the en-
ergy functional on a Riemannian manifold whose metric is discontinuous along a hypersurface /Sigma.
Such a study is motivated by the variational description of
refraction phenomena
Light rays having extreme points with the same spatial coordinates
No full textIn this paper we deal with lightlike geodesies in Lorentzian manifolds which are closed with respect to the spatial coordinates. We consider the case where the initial point is fixed or moves on a level of a given time function. The case where the initial point is free is also considered, under a periodicity condition on the metric
On the problem of the existence for connecting trajectories under the action of gravitational and electromagnetic fields
No full textInflation, Central Bank and short-term interest rates: A new model, with calibration to market data
Full text linkIn this paper, we propose a new model for the joint evolution of the inflation rate, the Central Bank official interest rate and the short-term interest rate. Our model takes into account the fact that the Central Bank interest rate changes at random times, inflation is measured at fixed, regular times, while the short-term interest rate evolves essentially continuously. We derive the valuation equation for a contingent claim and
show that it has a unique solution. The payoff may depend on all three economic factors of the model and the discount factor is allowed to include inflation. Our model is not an affine model. Although in some special cases the solution of the valuation equation might admit a closed form, in general it has to be solved numerically. This can be done efficiently by the algorithm that we provide. Taking as a benchmark the model of [H. W. Ho, H. H. Huang & Y. Yildirim (2014) Affine model of inflation-indexed derivatives and inflation risk premium, European Journal of Operational
Research 235, 159–169], we show that our model performs better on European market data from 2008 to 2015. Our model uses many fewer parameters than the benchmark model: This is advantageous from the numerical point of view and suggests that our model describes the behavior of the economic factors more closely
Risk Neutral Valuation of Inflation-Linked Interest Rate Derivatives
No full textWe propose a model for the joint evolution of European inflation, the European Central Bank official interest rate and the short-term interest rate, in a stochastic, continuous time setting. We derive the valuation equation for a contingent claim depending potentially on all three factors. This valuation equation reduces to a finite number of Cauchy problems for a degenerate parabolic PDE with non-local terms. We show that the price of the contingent claim is the only viscosity solution of the valuation equation. We also provide an efficient numerical scheme to compute the price and implement it in an example
Light rays having extreme points with the same spatial coordinates
No full textAbstractIn this paper we deal with lightlike geodesics in Lorentzian manifolds which are closed with respect to the spatial coordinates. We consider the case where the initial point is fixed or moves on a level of a given time function. The case where the initial point is free is also considered, under a periodicity condition on the metric
On a Class of Geodesically Connected Lorentzian Manifolds
No full textAbstractIn this paper we study the geodesical connectedness of Lorentzian manifolds. We consider a connected manifold M=M0×R, where M0is a complete Riemannian manifold endowed with a Lorentzian metricgof splitting type. We prove that, under suitable hypotheses on the coefficients of the metricg,Mis geodesically connected
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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