MFCS

El presente artículo trata sobre el proceso de construcción del régimen de Medidas de
Fomento de la Confianza y Seguridad (MFCS) en el ámbito de la Organización de
Estados Americanos. Se ha realizado un análisis del concepto de las MFCS, el cual
se ha venido desarrollando en el foro interamericano desde el principio de los años
90. Se han presentado problemas respecto a la falta de involucramiento de algunos
países de América Latina en la implementación de las MFCS, a la vez llamando la
atención sobre el hecho de que en esta región se las utiliza, principalmente, en las
relaciones bilaterales. Además, se ha hecho la evaluación del estado de las MFCS en
el hemisferio occidental y se ha presentado las perspectivas de su futuro desarrollo,
propagación y validación de su uso en América del Sur.

We study languages (i.e. sets) of planar directed acyclic graphs (pdags). These pdags are constructed by parallel composition and serial composition of letters and pdags on a doubly ranked alphabet. Our purpose is to introduce an algorithmic process (generalization of Kamimura and Slutzki's parallel automata) for accepting pdag languages and a specification of these languages by means of well-suited rational expressions. So our main result is a Kleene-like theorem proving the equivalence between rationality and automaton-definability.

The next bit test was introduced by Blum and Micali and proved by Yao to be a universal test for cryptographic pseudorandom generators. On the other hand, no universal test for the cryptographic one-wayness of functions (or permutations) is known, though the existence of cryptographic pseudorandom generators is equivalent to that of cryptographic one-way functions. In the quantum computation model, Kashefi, Nishimura and Vedral gave a sufficient condition of (cryptographic) quantum one-way permutations and conjectured that the condition would be necessary. In this paper, we relax their sufficient condition and give a new condition that is necessary and sufficient for quantum one-way permutations. Our condition can be regarded as a universal test for quantum one-way permutations, since our condition is described as a collection of stepwise tests similar to the next bit test for pseudorandom generators.

We propose several variations of the adversarial queueing model to cope with packets that can have different priorities, the priority and variable priority models, and link failures, the failure and reliable models. We address stability issues in the proposed adversarial models. We show that the set of universally stable networks in the adversarial model remains the same in the four introduced models. From the point of view of queueing policies we show that several queueing policies that are universally stable in the adversarial model remain so in the priority, failure and reliable models. However, we show that lis, a universally stable queueing policy in the adversarial model, is not universally stable in any of the other models, and that no greedy queueing policy is universally stable in the variable priority model. Finally we analyze the problem of deciding stability of a given network under a fixed protocol. We provide a characterization of the networks that are stable under fifo and lis in the failure model. This characterization allows us to show that deciding network stability under fifo and lis in the proposed models can be solved in polynomial time.

We study the relations between Multiplicative Exponential Linear Logic (mELL) and Baillot-Mazza Linear Logic by Levels (mL 3). We design a decoration-based translation between propositional mELL and propositional mL 3. The translation preserves the cut elimination. Moreover, we show that there is a proof net ${\it \Pi}$ of second order mELL that cannot have a representative ${\it \Pi'}$ in second order mL 3 under any decoration. This suggests that levels can be an analytical tool in understanding the complexity of second order quantifier.

A finite automaton, simply referred to as a robot, has to explore a graph, i.e., visit all the nodes of the graph. The robot has no a priori knowledge of the topology of the graph or of its size. It is known that, for any k-state robot, there exists a (k+1)-node graph of maximum degree 3 that the robot cannot explore. This paper considers the effects of allowing the system designer to add short labels to the graph nodes in a preprocessing stage, and using these labels to guide the exploration by the robot. We describe an exploration algorithm that given appropriate 2-bit labels (in fact, only 3-valued labels) allows a robot to explore all graphs. Furthermore, we describe a suitable labeling algorithm for generating the required labels, in linear time. We also show how to modify our labeling scheme so that a robot can explore all graphs of bounded degree, given appropriate 1-bit labels. In other words, although there is no robot able to explore all graphs of maximum degree 3, there is a robot \({\mathcal R}\) , and a way to color in black or white the nodes of any bounded-degree graph G, so that \({\mathcal R}\) can explore the colored graph G. Finally, we give impossibility results regarding graph exploration by a robot with no internal memory (i.e., a single state automaton).