Unifying Nominal Unification

International audienceNominal unification is proven to be quadratic in time and space. It was so by two different approaches, both inspired by the Paterson-Wegman linear unification algorithm, but dramatically different in the way nominal and first-order constraints are dealt with. To handle nominal constraints, Levy and Villaret introduced the notion of replacing while Calvès and Fernández use permutations and sets of atoms. To deal with structural constraints, the former use multi-equation in a way similar to the Martelli-Montanari algorithm while the later mimic Paterson-Wegman. In this paper we abstract over these two approaches and genralize them into the notion of modality, highlighting the general ideas behind nominal unification. We show that replacings and environments are in fact isomorphic. This isomorphism is of prime importance to prove intricate properties on both sides and a step further to the real complexity of nominal unification.Il est prouvé que l'unification nominale est quadratique en temps et en espace. Elle le fût par deux approches différentes, toutes deux inspirées de l'algorithme d'unification linéaire de Paterson et Wegman, mais très différentes dans leur manière de prendre en compte les contraintes nominales et celles du premier ordre. Pour traiter les contraintes nominales, Levy et Villaret ont introduit la notion de "replacing" alors que Calvès et Fernández ont utilisés des permutations et ensembles d'atomes. Pour prendre en compte les contraintes structurelles, les premiers utilisent des multi-équations à la manière de l'algorithme de Martelli et Montanari tandis que les seconds miment celui de Paterson et Wegman. Dans ce papier nous proposons une abstraction de ces deux approches et les généralisons à travers la notion de modalité, soulignant les idées générales sous-jacentes à l'unification nominale. Nous montrons que les "replacings" et les environnements sont en fait isomorphes. Cet isomorphisme est de première importance dans la démonstrations de propriétés complexes des deux cotés et une étape supplémentaire vers la complexité réelle de l'unification nominale

Faults in Linux 2.6

In August 2011, Linux entered its third decade. Ten years before, Chou et al. published a study of faults found by applying a static analyzer to Linux versions 1.0 through 2.4.1. A major result of their work was that the drivers directory contained up to 7 times more of certain kinds of faults than other directories. This result inspired numerous efforts on improving the reliability of driver code. Today, Linux is used in a wider range of environments, provides a wider range of services, and has adopted a new development and release model. What has been the impact of these changes on code quality? To answer this question, we have transported Chou et al.'s experiments to all versions of Linux 2.6; released between 2003 and 2011. We find that Linux has more than doubled in size during this period, but the number of faults per line of code has been decreasing. Moreover, the fault rate of drivers is now below that of other directories, such as arch. These results can guide further development and research efforts for the decade to come. To allow updating these results as Linux evolves, we define our experimental protocol and make our checkers available

Abstract TERMGRAPH 2006 Preliminary Version Implementing Nominal Unification

Nominal matching and unification underly the dynamics of nominal rewriting. Urban, Pitts and Gabbay gave a nominal unification algorithm which finds the most general solution to a nominal matching or unification problem, if one exists. Later the algorithm was extended by Fernández and Gabbay to deal with name generation and locality. In this paper we describe first a direct implementation of the nominal unification algorithm, including the extensions, in Maude. This implementation is not efficient (it is exponential in time), but we will show that we can obtain a feasible implementation by using termgraphs

Faults in Linux: Ten Years Later

In 2001, Chou et al. published a study of faults found by applying a static analyzer to Linux versions 1.0 through 2.4.1. A major result of their work was that the drivers directory contained up to 7 times more of certain kinds of faults than other directories. This result inspired a number of development and research efforts on improving the reliability of driver code. Today, however, Linux is used in a much wider range of environments, provides a much wider range of services, and has adopted a new development and release model. What has been the impact of these changes on code quality? Are drivers still a major problem? To answer these questions, we have attempted to transport, based on the information provided, the experiments of Chou et al. to Linux versions 2.6.0 to 2.6.33, released between late 2003 and early 2010. We find that even if Linux has more than doubled in size during this period, the number of faults per line of code has been decreasing. And, even though drivers still accounts for a large part of the kernel code and contains the most faults, its fault rate is now below that of other directories, such as arch (HAL) and fs (file systems). Such information can guide further development and research efforts. To enable others to continually update the results as Linux evolves, we define our experimental protocol and make our checkers and results available in a public archive.En 2001, Chou et al. ont publié une étude sur les fautes trouvées par analyse statique dans les versions 1.0 à 2.4.1 de Linux. Un résultat majeur de cette étude est que le répertoire drivers contenait jusqu'à 7 fois plus de fautes que d'autres répertoires. Ce résultat a inspiré de nombreux travaux de recherche afin d'améliorer la fiabilité du code des pilotes. Toutefois, Linux est utilisé à l'heure actuelle dans des environnements plus variés, il fourni plus de services, et un nouveau modèle de développement a été adopté. Quel sont l'impact de ces changements sur la qualité du code? Les pilotes sont ils toujours un problème majeur? Afin de répondre à ces questions, nous avons entrepris de transposer les expériences de Chou et al. aux versions de Linux 2.6.0 à 2.6.33, parues entre fin 2003 et début 2010. Nous observons que même si la taille de Linux à plus que doublée durant cette période, le nombre de fautes par ligne de code a diminué. Même si les pilotes représentent toujours une part importante du code du noyau et contiennent le plus de fautes, leur taux de fautes est maintenant inférieur à celui d'autres répertoires, comme arch (couche d'abstraction matérielle) et fs (systèmes de fichiers). De telles informations peuvent guider de nouveau travaux de recherche et développement. Afin de permettre une mise à jour de ces ces résultats par des tiers au fur et à mesure de l'évolution de Linux, nous définissons notre protocole d'expérimentation et rendons nos outils de vérifications ainsi que nos résultats disponibles dans une archive publique

Faults in Linux: Ten Years Later

In 2001, Chou et al. published a study of faults found by applying a static analyzer to Linux versions 1.0 through 2.4.1. A major result of their work was that the drivers directory contained up to 7 times more of certain kinds of faults than other directories. This result inspired a number of development and research efforts on improving the reliability of driver code. Today, however, Linux is used in a much wider range of environments, provides a much wider range of services, and has adopted a new development and release model. What has been the impact of these changes on code quality? Are drivers still a major problem? To answer these questions, we have attempted to transport, based on the information provided, the experiments of Chou et al. to Linux versions 2.6.0 to 2.6.33, released between late 2003 and early 2010. We find that even if Linux has more than doubled in size during this period, the number of faults per line of code has been decreasing. And, even though drivers still accounts for a large part of the kernel code and contains the most faults, its fault rate is now below that of other directories, such as arch (HAL) and fs (file systems). Such information can guide further development and research efforts. To enable others to continually update the results as Linux evolves, we define our experimental protocol and make our checkers and results available in a public archive.En 2001, Chou et al. ont publié une étude sur les fautes trouvées par analyse statique dans les versions 1.0 à 2.4.1 de Linux. Un résultat majeur de cette étude est que le répertoire drivers contenait jusqu'à 7 fois plus de fautes que d'autres répertoires. Ce résultat a inspiré de nombreux travaux de recherche afin d'améliorer la fiabilité du code des pilotes. Toutefois, Linux est utilisé à l'heure actuelle dans des environnements plus variés, il fourni plus de services, et un nouveau modèle de développement a été adopté. Quel sont l'impact de ces changements sur la qualité du code? Les pilotes sont ils toujours un problème majeur? Afin de répondre à ces questions, nous avons entrepris de transposer les expériences de Chou et al. aux versions de Linux 2.6.0 à 2.6.33, parues entre fin 2003 et début 2010. Nous observons que même si la taille de Linux à plus que doublée durant cette période, le nombre de fautes par ligne de code a diminué. Même si les pilotes représentent toujours une part importante du code du noyau et contiennent le plus de fautes, leur taux de fautes est maintenant inférieur à celui d'autres répertoires, comme arch (couche d'abstraction matérielle) et fs (systèmes de fichiers). De telles informations peuvent guider de nouveau travaux de recherche et développement. Afin de permettre une mise à jour de ces ces résultats par des tiers au fur et à mesure de l'évolution de Linux, nous définissons notre protocole d'expérimentation et rendons nos outils de vérifications ainsi que nos résultats disponibles dans une archive publique

Diagnostics of the Company CENTRUM Moravia Sever

Import 26/06/2013Diplomová práce pojednává o analýze podnikových aktivit společnosti Centrum Moravia Sever s. r. o. Podstatou této práce bylo provedení diagnostiky v této společnosti a následné zhodnocení diagnostických činností. První,teoretická část obsahuje poznatky, které se týkají metod, nástrojů a zdrojů pro provedení diagnostiky. Druhá část obsahuje charakteristiku diagnostikované společnosti. Další část je zaměřena na samotnou diagnostiku podniku. Čtvrtá a taky poslední část obsahuje celkové zhodnocení výsledků a doporučení vyplývající z této diagnostiky.This diploma thesis deals with the analysis of the business activities of Centrum Moravia Sever s.r.o. company. The nature of this work was to perform diagnostics of the company and subsequent evaluation of diagnostic activities. The first, theoretical part contains information related to the methods, tools and resources to perform the diagnostics. The second part contains the characteristics of the diagnosed company. Another part of the work focuses on the diagnostics of the company. The fourth and final part contains overall evaluation of the results and recommendations resulting from this diagnostics.152 - Katedra podnikohospodářskádobř

Activation of the MAPKs ERK1/2 by cell swelling in turbot hepatocytes.

International audienceBACKGROUND INFORMATION: Activation of MAPKs (mitogen-activated protein kinases), in particular ERK1/2 (extracellular-signal-regulated kinase 1/2), has been reported to take place in a large variety of cell types after hypo-osmotic cell swelling. Depending on cell type, ERK1/2 phosphorylation can then serve or not the RVD (regulatory volume decrease) process. The present study investigates ERK1/2 activation after aniso-osmotic stimulations in turbot hepatocytes and the potential link between phosphorylation of these proteins and RVD. RESULTS: In turbot hepatocytes, Western-blot analysis shows that a hypo-osmotic shock from 320 to 240 mOsm kg(-1) induced a rapid increase in ERK1/2 phosphorylation, whereas a hyper-osmotic shock from 320 to 400 mOsm kg(-1) induced no significant change in the phosphorylation of these proteins. The hypo-osmotic-induced ERK1/2 phosphorylation was significantly prevented when hypo-osmotic shock was performed in the presence of the specific MEK (MAPK/ERK kinase) inhibitor PD98059 (100 microM). In these conditions, the RVD process was not altered, suggesting that ERK1/2 did not participate in this process in turbot hepatocytes. Moreover, the hypo-osmotic-induced activation of ERK1/2 was significantly prevented by breakdown of extracellular ATP by apyrase (10 units ml(-1)), by inhibition of purinergic P2 receptors by suramin (100 microM) or by calcium depletion using EGTA (1 mM) and thapsigargin (1 microM). CONCLUSIONS: In turbot hepatocytes, hypo-osmotic swelling but not hyper-osmotic shrinkage induced the activation of ERK1/2. However, these proteins do not seem to be involved in the RVD process. Their hypo-osmotic-induced activation is partially due to cascades of signalling events triggered by the binding of released ATP on purinergic P2 receptors and requires the presence of calcium