Small clique number graphs with three trivial critical ideals

The critical ideals of a graph are the determinantal ideals of the generalized Laplacian matrix associated to a graph. In this article we provide a set of minimal forbidden graphs for the set of graphs with at most three trivial critical ideals. Then we use these forbidden graphs to characterize the graphs with at most three trivial critical ideals and clique number equal to 2 and 3.Comment: 33 pages, 3 figure

MANAGERIAL TURNOVER AND WORKER TURNOVER

We study the influence of the manager's degree of consolidation within the firm over the firm's labor policy. We argue that non-consolidated (recently-appointed) managers are more worried about short-term results than consolidated managers are. This feature leads the former to bias the labor contracting favoring short-term contracts. This has two main consequences. First, a higher variation in the number of workers hired in each period. And second, a lower increase in unitary labor costs. To contrast these results, we use a database of 1.054 Spanish companies during the period (1994-98), and analyze their managerial turnover as well as their corresponding variation in the number of workers and in unitary labor costs. The theoretical results are confirmed, especially for highly-productive (R&D-intensive) firms.

Massive 4d4d particle with torsion and conformal mechanics

The consequences of coupling of the torsion (highest curvature) term to the Lagrangian of a massive spinless particle in four-dimensional space-time are studied. It is shown that the modified system remains spinless and possesses extended gauge invariance. Though the torsion term does not generate spin, it provides the system with a nontrivial mass spectrum, described by one-dimensional conformal mechanics. Under an appropriate choise of characteristic constants the system has solutions with a discrete mass spectrum.Comment: 9 pages, revised version accepted in Phys.Lett.