The probability representation, in which cosmological quantum states are described by a standard positive probability distribution,
is constructed for minisuperspace models selected by Noether symmetries. In such a case, the tomographic probability distribution
provides the classical evolution for the models and can be considered an approach to select “observable” universes. Some specific
examples, derived from Extended Theories of Gravity, are worked out. We discuss also how to connect tomograms, symmetries
and cosmological parameters. 相似文献
A new generalized Farkas theorem of the alternative is presented for systems involving functions which can be expressed as the difference of sublinear functions. Various other forms of theorems of the alternative are also given using quasidifferential calculus. Comprehensive optimality conditions are then developed for broad classes of infinite dimensional quasidifferentiable programming problems. Applications to difference convex programming and infinitely constrained concave minimization problems are also discussed. 相似文献
Coordination polymers serving as molecular magnetic refrigerants have been attracting great interest. In particular, coordination cluster compounds that demonstrate their apparent advantages on cryogenic magnetic refrigerants have attracted more attention in the last five years. Herein, we mainly focus on depicting aspects of syntheses, structures, and magnetothermal properties of coordination clusters that serve as magnetic refrigerants on account of the magnetocaloric effect. The documented molecular magnetic refrigerants are classified into two primary categories according to the types of metal centers, namely, homo‐ and heterometallic clusters. Every section is further divided into several subgroups based on the metal nuclearity and their dimensionalities, including discrete molecular clusters and those with extended structures constructed from molecular clusters. The objective is to present a rough overview of recent progress in coordination‐cluster‐based molecular magnetic refrigerants and provide a tutorial for researchers who are interested in the field.
Although the theorems of the alternative have been well known for a long time, their relationship to linear least squares problems and steepest descent directions was revealed only recently. This relationship was used by the author to derive a new theorem of the alternative. The present research extends this theorem to the
p norm,p > 1. 相似文献
Absolute valued triple system are the natural ternary extension of absolute valued algebras. In this article we classify strongly power-associative absolute valued triple systems. 相似文献
We study the universal enveloping algebras of the one-parameter family of solvable 5-dimensional non-Lie Malcev algebras. We explicitly determine the universal nonassociative enveloping algebras (in the sense of Pérez-Izquierdo and Shestakov) and the centers of the universal enveloping algebras. We also determine the universal alternative enveloping algebras. 相似文献
We consider a Robin problem driven by a nonlinear, nonhomogeneous differential operator and a reaction term which depends on the gradient. Using a topological approach based on the Leray–Schauder Alternative Principle, we show the existence of a weak solution. 相似文献