Improved Sequential Stopping Rule for Monte Carlo Simulation

This paper presents an improved result on the negative-binomial Monte Carlo technique analyzed in a previous paper for the estimation of an unknown probability p. Specifically, the confidence level associated to a relative interval [p/\mu_2, p\mu_1], with \mu_1, \mu_2 > 1, is proved to exceed its asymptotic value for a broader range of intervals than that given in the referred paper, and for any value of p. This extends the applicability of the estimator, relaxing the conditions that guarantee a given confidence level.Comment: 2 figures. Paper accepted in IEEE Transactions on Communication

On global location-domination in graphs

A dominating set $S$ of a graph $G$ is called locating-dominating, LD-set for short, if every vertex $v$ not in $S$ is uniquely determined by the set of neighbors of $v$ belonging to $S$. Locating-dominating sets of minimum cardinality are called $LD$-codes and the cardinality of an LD-code is the location-domination number $\lambda(G)$. An LD-set $S$ of a graph $G$ is global if it is an LD-set of both $G$ and its complement $\overline{G}$. The global location-domination number $\lambda_g(G)$ is the minimum cardinality of a global LD-set of $G$. In this work, we give some relations between locating-dominating sets and the location-domination number in a graph and its complement.Comment: 15 pages: 2 tables; 8 figures; 20 reference

M&AS performance in the European financial industry

This paper looks at the performance record of M&As that took place in the European Union financial industry in the period 1998-2002. First, the paper reports evidence on shareholder returns from mergers. Merger announcements brought positive excess returns to the shareholders of the target company around the date of the announcement, with a slight positive excess return in the 3-month period prior to announcement. Returns to shareholders of the acquiring firms were essentially zero around announcement. One year after the announcement, excess returns were not significantly different from zero for either targets or acquirers. The paper also provides evidence on changes in operating performance for the subsample of mergers involving banks. M&As usually involved targets with lower-than-average operating performance for their sector. The transactions resulted in significant improvements in the target banks' performance, beginning on average two years after the transaction was completed. Return on equity of the target companies increased by an average of 7%, and the same firms also experienced efficiency improvements.mergers and acquisitions; financial industry;

Value creation in European M&As.

This paper looks at the value generated to shareholders by the announcement of mergers and acquisitions involving firms in the European Union. Target firm shareholders receive on average a statistically significant excess return of 9%. Acquirers' excess returns are null on average. Excess returns differ significantly depending on whether the merger involves two firms from the same European country or is a cross-border transaction. Cross-border transactions generate less total value than national mergers. Furthermore, when a cross-border merger occurs in an industry in which governments historically have been actively involved, the transaction results in a net destruction of value to shareholders.Cross-border mergers; shareholder returns; value creation; regulation

On the local Lorentz invariance in N=1 supergravity

We discuss the local Lorentz invariance in the context of N=1 supergravity and show that a previous attempt to find explicit solutions to the Lorentz constraint in terms of $\gamma-$matrices is not correct. We improve that solution by using a different representation of the Lorentz operators in terms of the generators of the rotation group, and show its compatibility with the matrix representation of the fermionic field. We find the most general wave functional that satisfies the Lorentz constraint in this representation