Carme Àlvarez

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We study universal stability of directed and undirected graphs in the adversarial queuing model for static packet routing. In this setting, packets are injected in some edge and have to traverse a predefined path before leaving the system. Restrictions on the allowed packet trajectory provide a way to analyze stability under different packet trajectories.(More)
In this paper we study the universal stability of undirected graphs in the adversarial queueing model for packet routing. In this setting, packets must be injected in some edge and have to traverse a path before leaving the system. Restrictions on the allowed types of path that packets must traverse provide different packet models. We consider three natural(More)
In this paper we present a way to establish a reliable and efficient high level communication system in a randomly deployed network of sensors equipped with directional antennas. Such high level communication system will enable the programming of the sensor network using high level communication functionalities without the burden of taking care of their(More)
We discuss two notions of functional oracle for logarithmic space-bounded machines, which differ in whether there is only one oracle tape for both the query and the answer or a separate tape for the answer, which can still be read while the next query is already being constructed. The first notion turns out to be basically nonadaptive, behaving like access(More)
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(More)