Distribution Policies for Datalog

Modern data management systems extensively use parallelism to speed up query processing over massive volumes of data. This trend has inspired a rich line of research on how to formally reason about the parallel complexity of join computation. In this paper, we go beyond joins and study the parallel evaluation of recursive queries. We introduce a novel framework to reason about multi-round evaluation of Datalog programs, which combines implicit predicate restriction with distribution policies to allow expressing a combination of data-parallel and query-parallel evaluation strategies. Using our framework, we reason about key properties of distributed Datalog evaluation, including parallel-correctness of the evaluation strategy, disjointness of the computation effort, and bounds on the number of communication rounds

Digital Preservation, Archival Science and Methodological Foundations for Digital Libraries

Digital libraries, whether commercial, public or personal, lie at the heart of the information society. Yet, research into their long‐term viability and the meaningful accessibility of their contents remains in its infancy. In general, as we have pointed out elsewhere, ‘after more than twenty years of research in digital curation and preservation the actual theories, methods and technologies that can either foster or ensure digital longevity remain startlingly limited.’ Research led by DigitalPreservationEurope (DPE) and the Digital Preservation Cluster of DELOS has allowed us to refine the key research challenges – theoretical, methodological and technological – that need attention by researchers in digital libraries during the coming five to ten years, if we are to ensure that the materials held in our emerging digital libraries are to remain sustainable, authentic, accessible and understandable over time. Building on this work and taking the theoretical framework of archival science as bedrock, this paper investigates digital preservation and its foundational role if digital libraries are to have long‐term viability at the centre of the global information society.

Scalable Uncertainty-tolerant Business Rules

The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-319-07617-1_16Business rules are of key importance for maintaining the correctness of business processes and the reliability of business data. When they take the form of integrity constraints, business rules also can help to contain the amount of uncertainty associated to business data and decisions based on those data. However, business rule enforcement may not scale up easily to systems with concurrent transactions. To a large extent, the problem is due to two common exigencies: the postulates of total and of isolated business rule satisfaction. In order to limit the accumulation of business rule violations, and thus of uncertainty, we are going to outline how a measure-based uncertainty-tolerant approach to business rules maintenance scales up to concurrent transactions. The scale-up is achieved by refraining from the postulates of total and isolated business rule satisfaction.Supported by ERDF/FEDER and the MEC grant TIN2012-37719-C03-01.Cuzzocrea, A.; Decker, H.; Muñoz-Escoí, FD. (2014). Scalable Uncertainty-tolerant Business Rules. En Hybrid Artificial Intelligence Systems: 9th International Conference, HAIS 2014, Salamanca, Spain, June 11-13, 2014. Proceedings. Springer Verlag (Germany). 179-190. https://doi.org/10.1007/978-3-319-07617-1_16S179190Abiteboul, S., Hull, R., Vianu, V.: Foundations of Databases. Addison-Wesley (1995)Abraham, A.: Hybrid approaches for approximate reasoning. Journal of Intelligent and Fuzzy Systems 23(2-3), 41–42 (2012)Bayer, R.: Integrity, concurrency, and recovery in databases. In: Samelson, K. (ed.) ECI 1976. LNCS, vol. 44, pp. 79–106. Springer, Heidelberg (1976)Berenson, H., Bernstein, P.A., Gray, J., Melton, J., O’Neil, E.J., O’Neil, P.E.: A critique of ansi sql isolation levels. 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Addison-Wesley Longman Publishing Co., Inc., Boston (2000)Decan, A., Pijcke, F., Wijsen, J.: Certain conjunctive query answering in SQL. In: Hüllermeier, E., Link, S., Fober, T., Seeger, B. (eds.) SUM 2012. LNCS, vol. 7520, pp. 154–167. Springer, Heidelberg (2012)Decker, H.: Causes for inconsistency-tolerant schema update management. In: ICDE Workshops, pp. 157–161 (2011)Decker, H.: Causes of the violation of integrity constraints for supporting the quality of databases. In: Murgante, B., Gervasi, O., Iglesias, A., Taniar, D., Apduhan, B.O. (eds.) ICCSA 2011, Part V. LNCS, vol. 6786, pp. 283–292. Springer, Heidelberg (2011)Decker, H.: Partial repairs that tolerate inconsistency. In: Eder, J., Bielikova, M., Tjoa, A.M. (eds.) ADBIS 2011. LNCS, vol. 6909, pp. 389–400. Springer, Heidelberg (2011)Decker, H.: Answers that have quality. In: Murgante, B., Misra, S., Carlini, M., Torre, C.M., Nguyen, H.-Q., Taniar, D., Apduhan, B.O., Gervasi, O. (eds.) ICCSA 2013, Part II. LNCS, vol. 7972, pp. 543–558. Springer, Heidelberg (2013)Decker, H., Martinenghi, D.: Inconsistency-tolerant integrity checking. IEEE Trans. Knowl. Data Eng. 23(2), 218–234 (2011)Decker, H., Muñoz-Escoí, F.D.: Revisiting and improving a result on integrity preservation by concurrent transactions. In: Meersman, R., Dillon, T., Herrero, P. (eds.) OTM 2010. LNCS, vol. 6428, pp. 297–306. Springer, Heidelberg (2010)Eswaran, K.P., Chamberlin, D.D.: Functional specifications of subsystem for database integrity. In: Kerr, D.S. (ed.) Proceedings of the International Conference on Very Large Data Bases, Framingham, Massachusetts, USA, September 22-24, pp. 48–68. ACM (1975)Eswaran, K.P., Gray, J., Lorie, R.A., Traiger, I.L.: The notions of consistency and predicate locks in a database system. Commun. ACM 19(11), 624–633 (1976)Gardarin, G.: Integrity, consistency, concurrency, reliability in distributed database management systems. 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Naturally Embedded Query Languages

We investigate the properties of a simple programming language whose main computational engine is structural recursion on sets. We describe a progression of sublanguages in this paradigm that (1) have increasing expressive power, and (2) illustrate robust conceptual restrictions thus exhibiting interesting additional properties. These properties suggest that we consider our sublanguages as candidates for "query languages". Viewing query languages as restrictions of our more general programming language has several advantages. First, there is no "impedance mismatch" problem; the query languages are already there, so they share common semantic foundation with the general language. Second, we suggest a uniform characterization of nested relational and complex-object algebras in terms of some surprisingly simple operators; and we can make comparisons of expressiveness in a general framework. Third, we exhibit differences in expressive power that are not always based on complexity arguments..

Data-Driven Regionalization of Decarbonized Energy Systems for Reflecting Their Changing Topologies in Planning and Optimization

The decarbonization of energy systems has led to a fundamental change in their topologysince generation is shifted to locations with favorable renewable conditions. In planning, this changeis reflected by applying optimization models to regions within a country to optimize the distributionof generation units and to evaluate the resulting impact on the grid topology. This paper proposesa globally applicable framework to find a suitable regionalization for energy system models witha data-driven approach. Based on a global, spatially resolved database of demand, generation,and renewable profiles, hierarchical clustering with fine-tuning is performed. This regionalizationapproach is applied by modeling the resulting regions in an optimization model including asynthesized grid. In an exemplary case study, South Africa’s energy system is examined. The resultsshow that the data-driven regionalization is beneficial compared to the common approach of usingpolitical regions. Furthermore, the results of a modeled 80% decarbonization until 2045 demonstratethat the integration of renewable energy sources fundamentally changes the role of regions withinSouth Africa’s energy system. Thereby, the electricity exchange between regions is also impacted,leading to a different grid topology. Using clustered regions improves the understanding and analysisof regional transformations in the decarbonization process

DEVELOPING ISLAMIC FINANCE OPPORTUNITIES FOR TRADE FINANCING: ESSAYS ON ISLAMIC TRADE VIS-À-VIS THE OIC TEN-YEAR PROGRAMME OF ACTION

International trade has been defined as the engine of growth by international development institutions as more cross-border trade associated with more economic activity, higher employment, hence, poverty alleviation. If trade is the engine of growth, trade finance can be defined as grease for the engine. Hence, availing more funds to finance the enormous amount of international trade, counting about half of global GDP, is an important agenda for the OIC as well as many multilateral development institutions. The main reason behind the efforts to avail more funds for trade finance is to direct valuable financial resources from speculation to explore opportunities to increase international trade in a way to grease and roll the wheel of real economy. With reference to the OIC Ten-Year Programme of Action to Meet the Challenges Facing the Muslim countries in the 21st century, this research aims to introduce outward-looking, cost-effective, and informal policy options for a resilient OIC trade integration to increase international trade among OIC countries. In this regard, the first essay aims to explore the determinants of recent increase in intra-OIC trade to ascertain if it is due to policy instruments implemented by OIC organs or some other externalities. It is argued that recent increase in intra-OIC trade percentage is likely to be the product of reverse effects of oil price surge and Euro appreciation but not trade diversion effect of OIC membership. OIC membership itself alone would not increase intra-OIC trade if not accompanied with policy instrument for trade facilitation to make cross-border trade easier among member countries. However, as customs revenue constitutes the bulk of public revenue for many OIC countries, they need to be convinced about benefit of trade facilitation. Accordingly, with reference to the unwillingness of OIC countries for trade facilitation, the same essay scrutinizes the effect of tariff and WTO Customs Valuation Agreement on customs’ revenue of OIC countries. The results suggest that increasing tariffs might increase customs revenue for big countries but not for small countries. Besides, the implementation of WTO Customs Valuation Agreement does not decrease customs revenue as its indirect undervaluation effect would be surpassed by its direct effect of less incentive for tax evasion. As a crucial crop for public finances in many OIC countries and initial stage of industrialization, special emphasis is given to development of the cotton sector under the OIC Ten-Year Programme of Action. The Third Expert Group Meeting on Enhancing Production Efficiency and International Competitiveness in OIC Cotton-Producing Countries adopted the Five-Year OIC Cotton Plan of Action (2007-2011). As per the mandate of OIC, two Islamic trade finance products are proposed, one for the cotton sector through the resources mobilized with mudarabah, by proposing salam for complete supply chain financing in the second essay, and another for resource mobilization based on 2-Step murabahah in the context of international trade as an alternative to commodity murabahah, sukuk as well as mudarabah in the third essay. In conclusion, based on further findings of the survey, the questionnaire and interviews; capacity building in trade facilitation for small countries to be complemented with OIC mutual recognition agreement for standard and conformity assessment within halal food standard development; integrated single window among OIC countries’ customs; OIC cumulation system of rules of origin for market access; inward processing relief as an alternative to free trade zones; development of the cotton sector among OIC countries to address production constraints of LDMCs and 2-Step murabahah to mobilize trade finance resources to boost trade of OIC countries, particularly for LDMCs, are proposed as a part of concretely defined and well-grounded OIC trade integration framework

Intuitionistic Databases and Cylindric Algebra

The goal of this thesis is to develop an intuitionistic relevance-logic based semantics that allows us to handle Full First Order queries similar monotone First Order queries. Next, we fully investigate the relational model and universal nulls, showing that they can be treated on par with the usual existential nulls. To do so, we show that a suitable finite representation mechanism, called Star-Cylinders, handling universal nulls can be developed based on the Cylindric Set Algebra. Moreover, we show that any First Order Relational Calculus query over databases containing universal nulls can be translated into an equivalent expression in our star cylindric algebra, and vice versa. Furthermore, the representation mechanism is then extended to Naive Star-Cylinders, which are star-cylinders allowing existential nulls in addition to universal nulls. Beside the theory part, we also provide a practical approach for four-valued databases. We show that the four-valued database instances can be stored as a pair of two-valued instances. These two-valued instances store positive and negative information independently, in the format of current databases. In a similar way, we show that four-valued queries can be decomposed to two-valued queries and can be executed against decomposed instances to obtain the four-valued the result, after merging them back. Later, we show how these results can be extended to Datalog and we show that there is no need for any syntactical notion of stratification or non-monotonic reasoning when the intuitionistic logic is implemented. This is followed by presenting the complexity results