Two-Player Reachability-Price Games on Single-Clock Timed Automata

We study two player reachability-price games on single-clock timed automata. The problem is as follows: given a state of the automaton, determine whether the first player can guarantee reaching one of the designated goal locations. If a goal location can be reached then we also want to compute the optimum price of doing so. Our contribution is twofold. First, we develop a theory of cost functions, which provide a comprehensive methodology for the analysis of this problem. This theory allows us to establish our second contribution, an EXPTIME algorithm for computing the optimum reachability price, which improves the existing 3EXPTIME upper bound.Comment: In Proceedings QAPL 2011, arXiv:1107.074

Examples of CM curves of genus two defined over the reflex field

In "Proving that a genus 2 curve has complex multiplication", van Wamelen lists 19 curves of genus two over $\mathbf{Q}$ with complex multiplication (CM). For each of the 19 curves, the CM-field turns out to be cyclic Galois over $\mathbf{Q}$. The generic case of non-Galois quartic CM-fields did not feature in this list, as the field of definition in that case always contains a real quadratic field, known as the real quadratic subfield of the reflex field. We extend van Wamelen's list to include curves of genus two defined over this real quadratic field. Our list therefore contains the smallest "generic" examples of CM curves of genus two. We explain our methods for obtaining this list, including a new height-reduction algorithm for arbitrary hyperelliptic curves over totally real number fields. Unlike Van Wamelen, we also give a proof of our list, which is made possible by our implementation of denominator bounds of Lauter and Viray for Igusa class polynomials.Comment: 31 pages; Updated some reference

Better abstractions for timed automata

We consider the reachability problem for timed automata. A standard solution to this problem involves computing a search tree whose nodes are abstractions of zones. These abstractions preserve underlying simulation relations on the state space of the automaton. For both effectiveness and efficiency reasons, they are parametrized by the maximal lower and upper bounds (LU-bounds) occurring in the guards of the automaton. We consider the aLU abstraction defined by Behrmann et al. Since this abstraction can potentially yield non-convex sets, it has not been used in implementations. We prove that aLU abstraction is the biggest abstraction with respect to LU-bounds that is sound and complete for reachability. We also provide an efficient technique to use the aLU abstraction to solve the reachability problem.Comment: Extended version of LICS 2012 paper (conference paper till v6). in Information and Computation, available online 27 July 201

Optimal Reachability in Divergent Weighted Timed Games

Weighted timed games are played by two players on a timed automaton equipped with weights: one player wants to minimise the accumulated weight while reaching a target, while the other has an opposite objective. Used in a reactive synthesis perspective, this quantitative extension of timed games allows one to measure the quality of controllers. Weighted timed games are notoriously difficult and quickly undecidable, even when restricted to non-negative weights. Decidability results exist for subclasses of one-clock games, and for a subclass with non-negative weights defined by a semantical restriction on the weights of cycles. In this work, we introduce the class of divergent weighted timed games as a generalisation of this semantical restriction to arbitrary weights. We show how to compute their optimal value, yielding the first decidable class of weighted timed games with negative weights and an arbitrary number of clocks. In addition, we prove that divergence can be decided in polynomial space. Last, we prove that for untimed games, this restriction yields a class of games for which the value can be computed in polynomial time

IRBIT a Master Regulator of Cell Physiology

(excerpt) Hormones and neurotransmitters regulate cell functions by binding to their receptors, which activate intracellular signaling and produce the physiological response [1]. There are several intracellular pathways, including but not limited to, leading to the activation of protein kinases, phosphatases and increase in intracellular calcium (Ca2+) [1]

Lutte contre les ectoparasites des bovins par pédiluve : método innovador utilizado en la zona peri urbana sub humeda de Burkina Faso

L'accroissement de la demande urbaine en protéines animales se traduit, entre autres, par le développement de filières bovines de production laitière dans les zones périurbaines d'Afrique de l'Ouest. Mais la maîtrise imparfaite des maladies et des parasites compromet la croissance de la production. Une technique de lutte innovante, basée sur le passage régulier dans un pédiluve contenant une formulation aqueuse d'un pyréthrinoïde, pourrait pourtant limiter l'impact des tiques et des glossines, principales contraintes pathologiques en zone subhumide. Cette méthode entraîne l'élimination de la plupart des adultes d'Amblyomma variegatum, la tique la plus nocive dans ces régions, avant leur fixation définitive. D'autre part, un tel traitement permet de diminuer fortement la population des glossines riveraines les plus représentées en Afrique occidentale (Glossina tachinoides et G. palpalis gambiensis) et donc de limiter l'incidence des trypanosomoses. Cette méthode assure ainsi une lutte rapide et efficace à coût réduit car la quantité de produit utilisé à chaque passage est faible. Mais la construction de l'installation, qui peut être utilisée par 400 à 600 animaux, représente un investissement non négligeable que des groupements d'éleveurs ou des investisseurs privés peuvent plus facilement prendre en charge que des éleveurs traditionnels isolés. La mise en place de cette méthode peut ainsi être envisagée dans le cadre d'une politique de développement et d'aménagement. L'intérêt et les modalités de l'appui technique nécessaire sont présentés. Au Burkina Faso, un projet d'appui au renforcement des organisations professionnelles d'éleveurs modernes (Ariope) a de la sorte financé quinze installations dans les zones périurbaines de Bobo-Dioulasso et Ouagadougou. (Résumé d'auteur