The data-exchange chase under the microscope

In this paper we take closer look at recent developments for the chase procedure, and provide additional results. Our analysis allows us create a taxonomy of the chase variations and the properties they satisfy. Two of the most central problems regarding the chase is termination, and discovery of restricted classes of sets of dependencies that guarantee termination of the chase. The search for the restricted classes has been motivated by a fairly recent result that shows that it is undecidable to determine whether the chase with a given dependency set will terminate on a given instance. There is a small dissonance here, since the quest has been for classes of sets of dependencies guaranteeing termination of the chase on all instances, even though the latter problem was not known to be undecidable. We resolve the dissonance in this paper by showing that determining whether the chase with a given set of dependencies terminates on all instances is coRE-complete. For the hardness proof we use a reduction from word rewriting systems, thereby also showing the close connection between the chase and word rewriting. The same reduction also gives us the aforementioned instance-dependent RE-completeness result as a byproduct. For one of the restricted classes guaranteeing termination on all instances, the stratified sets dependencies, we provide new complexity results for the problem of testing whether a given set of dependencies belongs to it. These results rectify some previous claims that have occurred in the literature.Comment: arXiv admin note: substantial text overlap with arXiv:1303.668

Study of the microbiological activity in the agrocenosis from Crisurilor Plain

The seasonal variations of soil microorganisms depend on changes in the soil chemical properties and the microbiological processes of soil are determined in main by different cropping systems, soil management and season. Investigation of the microbiological properties of a haplic luvisol, under different cultivation conditions showed that anthropogenic factors such as fertilization and treatments with pesticides was favourable for certain microorganisms while others were inhibited by these factors. In order the quantitative occurence of microorganism was aerobic mesophilic heterotrophs (105–107 cellsxg-1 dry matter soil) were followed by Actinomycetes, yeast and mould (103–106 cellsxg-1 dry matter soil), nitrogen fixing bacteria (102–105 cellsxg-1 dry matter soil) and nitrifying bacteria (10-1–103 cellsxg-1 dry matter soil). The highest values of aerobic mesophilic heterotrophs were found in cropland and undisturbed meadow of haplic luvisol. Actinomycetes are more developed in undisturbed soils than in the cultivated soils. The number of yeast and mould was high in the apricot tree orchard, and Azotobacter and nitrifying bacteria were identified in a small number in all the soil variants studied. Among the total number of aerobic microorganisms, pH and humus content statistically proved relationship was established. Total number of yeast and mould depends on the proportion of 10.89% by moisture content and pH. The numerical presence of Azotobacter depends in a proportion of 9.6% by the ammonia nitrogen content and pH variations. The numerical presence of nitrifying bacteria depends in a proportion of 1.69% by the nitric nitrogen content and humus content variation

Evaluation of the microbial soil quality indicators in agricultural soils from Crisurilor Plain

The researches were carried out in 2010 and 2011 on the haplic luvisol cultivated in three variant such as: pasture, cropland, and orchards. Based on the total number of microorganisms monitored in the haplic luvisol (aerobic mesophilic heterotrophs, yeast and mould, Actinomycetes, nitrogen fixing bacteria and nitrifying bacteria) was calculated the bacterial indicators of soil quality (BISQ) and was appreciate the bacterial potential of the haplic luvisol. Seasonal analyses were carried out, and annual BISQs have been calculated too. The values of the bacterial indicators of the haplic luvisol in different cultivation conditions (pasture, cropland and orchards) indicate a high density of the bacterial groups in 2010 and 2011. In 2010 the values of the BISQs are included between 3.617 (minimum in autumn, in pasture) and 5.458 (maximum, in spring, in pasture). In 2011, the minimum value (3.622) was registered in pasture, in autumn, and the maximum value (4.851) in the haplic luvisol cultivated with maize, in spring. In 2010 and 2011, based on the bacterial indicators of the soil quality values, on the first position is the cropland (4.750, 4.721) followed by orchards (4.615, 3.985) and pasture (4.537, 3.758)

Continuité et métamorphoses du surréalisme bruxellois : la poétique de l’illisible chez Christian Dotremont

Cette thèse pose la question de la fortune remarquable du surréalisme en Belgique et porte particulièrement attention à la poétique de Christian Dotremont qui, après une période surréaliste, trace le premier logogramme en 1962. La partie initiale de notre recherche interroge ses rapports avec le groupe surréaliste bruxellois (Paul Nougé et René Magritte), préoccupé par le refus de l’œuvre. Cette démarche subversive se transforme dans l’art expérimental du groupe Cobra (communauté artistique fondée en 1948 par Dotremont). Nous nous intéressons à cette évolution d’une préoccupation logocentrique (où le mot compte pour le contenu qu’il véhicule : il s’agit de la poétique « primitive » de Nougé et des objets bouleversants de Magritte) vers l’exploration du mot comme trace, comme scription et, par là même, comme source de poésie. La deuxième partie de notre recherche traite de l’époque Cobra où se forge ce que nous appelons la poétique du visible chez Dotremont dont le résultat est la découverte du pouvoir créatif du mot en tant que matière, en tant que trace manuscrite. Ces expérimentations centrées sur la matérialité du langage préparent le cheminement artistique de Dotremont vers l’invention du logogramme (objet d’analyse de la troisième partie de la thèse). Dans l’idée d’une légitimation du logogramme en tant que nouveau genre poético-pictural, nous relevons ses invariants créateurs : sans pour autant se soumettre au modèle pictural, celui-ci n’est ni peinture des mots, ni mot-tableau, il exploite la matérialité de la lettre comme source poétique : genre transfrontalier qui ne cesse de mettre en question et d’inclure dans sa cinétique la métamorphose de sa réception.The main focus of our research points out the noteworthy longevity of the Belgian surrealist group. Thus, we have chosen to analyze the poetic and artistic works of one of its most important representative, Christian Dotremont. His interartistic poetics (beginning with a surrealist phase and continuing until the invention of the logograms in 1962) is in fact symptomatic for the complete transformation of the Belgian movement. Consequently, the first part of our research examines Dotremont’s contacts and collaborations with the surrealist group (Paul Nougé and René Magritte), mainly interested by subversive creative works. Their negative technique is transformed by Dotremont into experimental art along with his own group founded in 1948, Cobra. The second part of this research would particularly like to draw attention to this evolution from a logocentric artistic point of view in which the word is important for its meaning (Nougé’s “primitive” poetry theory or Magritte’s praxis of “objets bouleversants”) toward Dotremont and Cobra’s discovery of the word as materiality, as scription, and as poetic source. This is the object of the second part of our thesis, where we explore Cobra “poetics of visible”: the pictorial and poetic importance of painted not written texts, words or letters. Cobra collective inventions investigate the aesthetic results of in-between artistic techniques and also emphasize Dotremont progression from a subversive surrealist literary point of view to the invention of logograms. This hybrid creation, the logogram, is examined in detail in the third and last part of our thesis

The chase procedure and its applications

The goal of this thesis is not only to introduce and present new chase-based algorithms, but also to investigate the differences between the main existing chase procedures. In order to achieve this, first we will investigate and do a clear delimitation between the existing chase algorithms based on their termination criteria. This will give a better picture of which chase algorithm can be used for different dependency classes. Next, we will investigate the data exchange, data repair and data correspondence problems and show how the chase algorithm can be used to characterize different types of solutions. For the later two problems, we will also investigate the data complexity of solution-existence and solution-check problems. Further, we will introduce a new chase based algorithm which computes representative solutions under constructible models, a new closed world semantics. This new semantics is, in our view, appropriate to be used as a closed world semantics in data exchange. We will also show that the conditional table computed by this chase algorithm can help to get both possible and certain answers for general queries. And finally, we will investigate strong representation systems and strong data exchange representation system. We will prove, by introducing a new chase based algorithm, that mappings specified by source-to-target second order dependencies and target richly acyclic TGD’s are strong data exchange representation systems for the class of first order queries

HELP – Home Electronics Laboratory Platform –Development And Evaluation

In response to the COVID pandemic, many of our undergraduate students were supplied with custom development kits to undertake their electronic laboratory activities at home. Following our return to on-campus teaching, we plan to combine on-campus laboratory sessions with at-home experiments taking advantage of both on-campus and at-home experimental work while avoiding some of the limitations experienced during remote teaching. The goal is to embed active learning as a key part of a long-term strategy to enable students to better manage their learning and to maximise the analytical engagement with lecturers in a hybrid blend of on-campus and remote activities. In this paper, we report on three generations of the at-home laboratory kit developed by the author\u27s institute and partners in the Erasmus+ project “Home Electronics Laboratory Platform (HELP)”. The HELP kit comprises a portable signal generator and measurement instrument and a custom electronic board, which includes several functional blocks alongside the usual breadboard for assembling circuits with discrete components. The motivation for the design of each generation is introduced and the desired functionality and its implementation are described. The impact and user experience with the kits have been assessed through student surveys and staff focus groups in the HELP consortium partners. The main themes associated with take-home electronics laboratories have also been explored in a workshop with HELP partners and contributors from other universities across Europe and the USA. This work is summarised and future potential technical and pedagogical developments are outlined