Simón Bolívar University

About: Simón Bolívar University is a education organization based out in Caracas, Venezuela. It is known for research contribution in the topics: Population & Crystallization. The organization has 5912 authors who have published 8294 publications receiving 126152 citations.

General relativistic electromagnetic mass models of neutral spherically symmetric systems

Abstract: The recent work of Gron [1] concerning charged analogues of Florides' class of solutions is discussed and generalized. The properties of this kind of model are investigated. In particular it is shown that the ratiom/r as well as the acceleration of gravity are maximum inside the body rather than at the boundary. Some exact solutions of the Einstein-Maxwell equations illustrating these properties are presented. The solutions are matched continuously to the exterior Schwarzschild solution and they represent electromagnetic mass models of neutral systems. All physical quantities are finite inside the distributions. The energy density is positive and decreases monotonically from its maximum value at the center to zero at the boundary.

Learning depth-first search: a unified approach to heuristic search in deterministic and non-deterministic settings, and its application to MDPs

Abstract: Dynamic Programming provides a convenient and unified framework for studying many state models used in AI but no algorithms for handling large spaces. Heuristic-search methods, on the other hand, can handle large spaces but lack a common foundation. In this work, we combine the benefits of a general dynamic programming formulation with the power of heuristic-search techniques for developing an algorithmic framework, that we call Learning Depth-First Search, that aims to be both general and effective. LDFS is a simple piece of code that performs iterated depth-first searches enhanced with learning. For deterministic actions and monotone value functions, LDFS reduces to IDA* with transposition tables, while for Game Trees, to the state-of-the-art iterated Alpha-Beta search algorithm with Null Windows known as MTD. For other models, like AND/OR graphs and MDPs, LDFS yields new, simple, and competitive algorithms. We show this here for MDPs.

The Kronecker Product of Schur Functions Indexed by Two-Row Shapes or Hook Shapes

Abstract: The Kronecker product of two Schur functions i>sμ and i>sν, denoted by i>sμ a i>sν, is the Frobenius characteristic of the tensor product of the irreducible representations of the symmetric group corresponding to the partitions μ and ν The coefficient of i>sλ in this product is denoted by γλμν, and corresponds to the multiplicity of the irreducible character χλ in χμχν We use Sergeev's Formula for a Schur function of a difference of two alphabets and the comultiplication expansion for i>sλ[i>XY] to find closed formulas for the Kronecker coefficients γλμν when λ is an arbitrary shape and μ and ν are hook shapes or two-row shapes Remmel (JB Remmel, i>J Algebra 120 (1989), 100–118; i>Discrete Math 99 (1992), 265–287) and Remmel and Whitehead (JB Remmel and T Whitehead, i>Bull Belg Math Soc Simon Stiven 1 (1994), 649–683) derived some closed formulas for the Kronecker product of Schur functions indexed by two-row shapes or hook shapes using a different approach We believe that the approach of this paper is more natural The formulas obtained are simpler and reflect the symmetry of the Kronecker product