Algebro-Geometric Solutions of the Generalized Virasoro Constraints

We will describe algebro-geometric solutions of the KdV hierarchy whose $\tau$-functions in addition satisfy a generalization of the Virasoro constraints (and, in particular, a generalization of the string equation). We show that these solutions are closely related to embeddings of the positive half of the Virasoro algebra into the Lie algebra of differential operators on the circle. Our results are tested against the case of Witten-Kontsevich $\tau$-function. As by-products, we exhibit certain links of our methods with double covers of the projective line equipped with a line bundle and with ${\rm Gl}(n)$-opers on the punctured disk

The ring compression test: Analysis of dimensions and canonical geometry

The compression ring test is universally accepted as a perfectly valid method by which determine simply and reliably the adhesion friction factor in a plastic deformation process. Its methodology is based on the application of geometric changes as both the reduction in thickness as the decrease in bore inner diameter in the strained ring itself. In this paper the performance of that test is the basis for establishing the coefficient of friction on a forging process so that, given this, its application to Upper Bound Theorem (UBT) by model Triangular Rigid Zones (TRZ), enable the establishment an intercomparison with empirical force, reaching a cuasivalidation of this Theorem in a certain range.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Towards Understanding Reasoning Complexity in Practice

Although the computational complexity of the logic underlying the standard OWL 2 for the Web Ontology Language (OWL) appears discouraging for real applications, several contributions have shown that reasoning with OWL ontologies is feasible in practice. It turns out that reasoning in practice is often far less complex than is suggested by the established theoretical complexity bound, which reflects the worstcase scenario. State-of-the reasoners like FACT++, HERMIT, PELLET and RACER have demonstrated that, even with fairly expressive fragments of OWL 2, acceptable performances can be achieved. However, it is still not well understood why reasoning is feasible in practice and it is rather unclear how to study this problem. In this paper, we suggest first steps that in our opinion could lead to a better understanding of practical complexity. We also provide and discuss some initial empirical results with HERMIT on prominent ontologie

The organizational design of nonprofits for people with disabilities

Utilizando información obtenida de los directivos de 105 pequeñas organizaciones sin fines de lucro españolas que, en el año 2007, se dedicaban a la prestación de servicios a personas con discapacidad, hemos analizado como el diseño organizativo –en concreto, los sistemas de recompensas extrínsecas e intrínsecas- influye sobre la delegación, la motivación y la transferencia de conocimiento a la hora de lograr el objetivo de la organización consistente en mejorar la calidad de vida de las personas que viven con una discapacidad. Los resultados muestran que, debido a la carencia de conocimiento técnico, los directivos de estas entidades no lucrativas (ENL) deben delegar derechos de decisión en empleados cualificados y utilizar en mayor medida recompensas intrínsecas y extrínsecas para motivar a los empleados a que transmitan conocimiento entre ellos eficientemente.We use data obtained from managers of 105 small nonprofit organizations (NPOs) providing services to people with disabilities in Spain in 2007 to examine how organizational design—particularly, extrinsic and intrinsic reward systems—impacts delegation, motivation, and knowledge transfer to achieve the NPO’s goal to improve the lives of persons living with disabilities. We find that, due to lack of technical knowledge, managers of these NPOs must delegate decision rights to qualified employees and that they successfully use a higher degree of intrinsic and extrinsic rewards to motivate employees to transfer knowledge among themselves efficiently

A decomposition procedure based on approximate newton directions

The efficient solution of large-scale linear and nonlinear optimization problems may require exploiting any special structure in them in an efficient manner. We describe and analyze some cases in which this special structure can be used with very little cost to obtain search directions from decomposed subproblems. We also study how to correct these directions using (decomposable) preconditioned conjugate gradient methods to ensure local convergence in all cases. The choice of appropriate preconditioners results in a natural manner from the structure in the problem. Finally, we conduct computational experiments to compare the resulting procedures with direct methods, as well as to study the impact of different preconditioner choices