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Un nuevo resultado sobre la complejidad del problema del p-centro.

José Andrés Moreno Pérez (1990)

Trabajos de Investigación Operativa

Sea G un grafo no dirigido con n vértices y m aristas. Un p-Centro de G es un conjunto de p puntos en el que se minimiza la distancia al vértice más lejano. Esta distancia mínima es el p-Radio de G. Un Centro Local es un punto c a la misma distancia (llamada rango del centro local) de un conjunto no vacío de vértices que no son todos accesibles a través de un mismo vértice adyacente a c. Todo p-radio es el rango de algún centro local, por tanto, para resolver el problema del p-centro basta encontrar...

Un ordonnancement dynamique de tâches stochastiques sur un seul processeur

Ali Derbala (2002)

RAIRO - Operations Research - Recherche Opérationnelle

Nous montrons qu’une priorité dynamique particulière allouée aux tâches dans un système d’exploitation d’ordinateurs multitâches s’interprète comme deux problèmes d’ordonnancement particuliers, l’ordonnancement de tâches détériorantes à durée opératoires variables et de tâches en retard ou en attente de réparation de la machine. Deux propositions sur son comportement sont énoncées. Sous certaines conditions nous montrons qu’elle est une règle d’indice. Pour le faire, nous présentons l’outil des...

Un ordonnancement dynamique de tâches stochastiques sur un seul processeur

Ali Derbala (2010)

RAIRO - Operations Research

We show that a particular dynamic priority given to jobs in a multitasks operating system of computers is a deteriorating jobs or a delaying jobs scheduling. Under some assumptions we also show that it is an index rule. To do this, we present the tool of bandit processes to solve stochastic scheduling problems on a single machine.

Una aplicación de la técnica multiedit-condensing a la segmentación de escenas naturales en color.

Francisco Ferri Rabasa, Enrique Vidal Ruiz (1991)

Qüestiió

Se presenta una adaptación de la técnica Multiedit-Condensing (MC) recientemente aplicada a algunos problemas en Reconocimiento de Formas, a un problema de segmentación de imágenes que se encuadra dentro del marco general del Análisis de Imagen en Robótica. Se presenta una revisión de los fundamentos de dicha técnica y se justifica su uso para la solución del problema propuesto. Dicho problema consiste básicamente en la separación de las distintas zonas de interés en una imagen, según su color y...

Unambiguous erasing morphisms in free monoids

Johannes C. Schneider (2010)

RAIRO - Theoretical Informatics and Applications

This paper discusses the fundamental combinatorial question of whether or not, for a given string α, there exists a morphism σ such that σ is unambiguous with respect to α, i.e. there exists no other morphism τ satisfying τ(α) = σ(α). While Freydenberger et al. [Int. J. Found. Comput. Sci. 17 (2006) 601–628] characterise those strings for which there exists an unambiguous nonerasing morphism σ, little is known about the unambiguity of erasing morphisms, i.e. morphisms that map symbols...

Unambiguous recognizable two-dimensional languages

Marcella Anselmo, Dora Giammarresi, Maria Madonia, Antonio Restivo (2006)

RAIRO - Theoretical Informatics and Applications

We consider the family UREC of unambiguous recognizable two-dimensional languages. We prove that there are recognizable languages that are inherently ambiguous, that is UREC family is a proper subclass of REC family. The result is obtained by showing a necessary condition for unambiguous recognizable languages. Further UREC family coincides with the class of picture languages defined by unambiguous 2OTA and it strictly contains its deterministic counterpart. Some closure and non-closure properties of...

Unavoidable Set: Extension and Reduction

Phan Trung Huy, Nguyen Huong Lam (2010)

RAIRO - Theoretical Informatics and Applications

We give an explicit criterion for unavoidability of word sets. We characterize extendible, finitely and infinitely as well, elements in them. We furnish a reasonable upper bound and an exponential lower bound on the maximum leghth of words in a reduced unavoidable set of a given cardinality.

Undecidability of infinite post correspondence problem for instances of size 8

Jing Dong, Qinghui Liu (2012)

RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications

The infinite Post Correspondence Problem (ωPCP) was shown to be undecidable by Ruohonen (1985) in general. Blondel and Canterini [Theory Comput. Syst. 36 (2003) 231–245] showed that ωPCP is undecidable for domain alphabets of size 105, Halava and Harju [RAIRO–Theor. Inf. Appl. 40 (2006) 551–557] showed that ωPCP is undecidable for domain alphabets of size 9. By designing a special coding, we delete a letter from Halava and Harju’s construction. So we prove that ωPCP is undecidable for domain alphabets...

Undecidability of infinite post correspondence problem for instances of size 8

Jing Dong, Qinghui Liu (2012)

RAIRO - Theoretical Informatics and Applications

The infinite Post Correspondence Problem (ωPCP) was shown to be undecidable by Ruohonen (1985) in general. Blondel and Canterini [Theory Comput. Syst. 36 (2003) 231–245] showed that ωPCP is undecidable for domain alphabets of size 105, Halava and Harju [RAIRO–Theor. Inf. Appl. 40 (2006) 551–557] showed that ωPCP is undecidable for domain alphabets of size 9. By designing a special coding, we delete a letter from Halava and Harju’s construction. So we prove that ωPCP is undecidable for domain alphabets...

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