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Graph databases provide a natural way of storing and querying graph data. In contrast to relational databases, queries over graph databases enable to refer directly to the graph structure of such graph data. For example, graph pattern matching can be employed to formulate queries over graph data.
However, as for relational databases running complex queries can be very time-consuming and ruin the interactivity with the database. One possible approach to deal with this performance issue is to employ database views that consist of pre-computed answers to common and often stated queries. But to ensure that database views yield consistent query results in comparison with the data from which they are derived, these database views must be updated before queries make use of these database views. Such a maintenance of database views must be performed efficiently, otherwise the effort to create and maintain views may not pay off in comparison to processing the queries directly on the data from which the database views are derived.
At the time of writing, graph databases do not support database views and are limited to graph indexes that index nodes and edges of the graph data for fast query evaluation, but do not enable to maintain pre-computed answers of complex queries over graph data. Moreover, the maintenance of database views in graph databases becomes even more challenging when negation and recursion have to be supported as in deductive relational databases.
In this technical report, we present an approach for the efficient and scalable incremental graph view maintenance for deductive graph databases. The main concept of our approach is a generalized discrimination network that enables to model nested graph conditions including negative application conditions and recursion, which specify the content of graph views derived from graph data stored by graph databases. The discrimination network enables to automatically derive generic maintenance rules using graph transformations for maintaining graph views in case the graph data from which the graph views are derived change. We evaluate our approach in terms of a case study using multiple data sets derived from open source projects.
Graph transformation systems are a powerful formal model to capture model transformations or systems with infinite state space, among others. However, this expressive power comes at the cost of rather limited automated analysis capabilities. The general case of unbounded many initial graphs or infinite state spaces is only supported by approaches with rather limited scalability or expressiveness. In this report we improve an existing approach for the automated verification of inductive invariants for graph transformation systems. By employing partial negative application conditions to represent and check many alternative conditions in a more compact manner, we can check examples with rules and constraints of substantially higher complexity. We also substantially extend the expressive power by supporting more complex negative application conditions and provide higher accuracy by employing advanced implication checks. The improvements are evaluated and compared with another applicable tool by considering three case studies.
Babelsberg/RML
(2015)
New programming language designs are often evaluated on concrete implementations. However, in order to draw conclusions about the language design from the evaluation of concrete programming languages, these implementations need to be verified against the formalism of the design. To that end, we also have to ensure that the design actually meets its stated goals. A useful tool for the latter has been to create an executable semantics from a formalism that can execute a test suite of examples. However, this mechanism so far did not allow to verify an implementation against the design.
Babelsberg is a new design for a family of object-constraint languages. Recently, we have developed a formal semantics to clarify some issues in the design of those languages. Supplementing this work, we report here on how this formalism is turned into an executable operational semantics using the RML system. Furthermore, we show how we extended the executable semantics to create a framework that can generate test suites for the concrete Babelsberg implementations that provide traceability from the design to the language. Finally, we discuss how these test suites helped us find and correct mistakes in the Babelsberg implementation for JavaScript.
The present lecture notes aim for an introduction to the ergodic behaviour of Markov Processes and addresses graduate students, post-graduate students and interested readers.
Different tools and methods for the study of upper bounds on uniform and weak ergodic rates of Markov Processes are introduced. These techniques are then applied to study limit theorems for functionals of Markov processes.
This lecture course originates in two mini courses held at University of Potsdam, Technical University of Berlin and Humboldt University in spring 2013 and Ritsumameikan University in summer 2013.
Alexei Kulik, Doctor of Sciences, is a Leading researcher at the Institute of Mathematics of Ukrainian National Academy of Sciences.
The in-memory revolution
(2015)
This book describes the next generation of business applications enabled by SAP's in-memory database, SAP HANA. In particular, the authors show the substantial changes introduced in S4/HANA by switching to SAP HANA. Using numerous examples and use cases from the authors' wealth of real-world experience, it illustrates the quantum leap in performance made possible by the new technology. The book is written by two of the most prominent actors in the area of business application systems: Hasso Plattner, co-founder of SAP and inaugurator of the Hasso Plattner Institute at the University of Potsdam, and Bernd Leukert, member of the Executive Board and the Global Managing Board of SAP. This clearly structured, highly illustrated book takes an exciting new technology and presents the practicality and success of first mover applications.
Parts without a whole?
(2015)
This explorative study gives a descriptive overview of what organizations do and experience when they say they practice design thinking. It looks at how the concept has been appropriated in organizations and also describes patterns of design thinking adoption. The authors use a mixed-method research design fed by two sources: questionnaire data and semi-structured personal expert interviews. The study proceeds in six parts: (1) design thinking¹s entry points into organizations; (2) understandings of the descriptor; (3) its fields of application and organizational localization; (4) its perceived impact; (5) reasons for its discontinuation or failure; and (6) attempts to measure its success. In conclusion the report challenges managers to be more conscious of their current design thinking practice. The authors suggest a co-evolution of the concept¹s introduction with innovation capability building and the respective changes in leadership approaches. It is argued that this might help in unfolding design thinking¹s hidden potentials as well as preventing unintended side-effects such as discontented teams or the dwindling authority of managers.
MULTILIT
(2015)
This paper presents an overview of the linguistic analyses developed in the MULTILIT project and the processing of the oral and written texts collected. The project investigates the language abilities of multilingual children and adolescents, in particular, those who have Turkish and/or Kurdish as a mother tongue. A further aim of the project is to examine from a psycholinguistic and sociolinguistic perspective the extent to which competence in academic registers is achieved on the basis of the languages spoken by the children, including the language(s) spoken at the home, the language of the country of residence and the first foreign language. To be able to examine these questions using corpus linguistic parameters, we created categories of analysis in MULTILIT.
The data collection comprises texts from bilingual and monolingual children and adolescents in Germany in their first language Turkish, their second language German und their foreign language English. Pupils aged between nine and twenty years of age produced monologue oral and written texts in the two genres of narrative and discursive. On the basis of these samples, we examine linguistic features such as lexical expression (lexical density, lexical diversity), syntactic complexity (syntactic and discursive packaging) as well as phonology in the oral texts and orthography in the written texts, with the aim of investigating the pupils’ growing mastery of these features in academic and informal registers.
To this end the raw data have been transcribed by the use of transcription conventions developed especially for the needs of the MULTILIT data. They are based on the commonly used HIAT and GAT transcription conventions and supplemented with conventions that provide additional information such as features at the graphic level.
The categories of analysis comprise a large number of linguistic categories such as word classes, syntax, noun phrase complexity, complex verbal morphology, direct speech and text structures. We also annotate errors and norm deviations at a wide range of levels (orthographic, morphological, lexical, syntactic and textual). In view of the different language systems, these criteria are considered separately for all languages investigated in the project.
This volume discusses the impact of human rights law on other fields of international law. Does international human rights law modify other fields of international law? Contributions focus on possible spillover effects of human rights on international economic or international criminal law. Does international human rights law have a streamlining effect on international law as a whole? This might be identified as a process of constitutionalisation. In this book, human rights can be understood as one of the core principles of international legal order and thus have an effect on the general law of treaties or on the settlement of disputes.
Although human rights law is a relatively young field of international law, its content and core values today are of major importance for the interpretation of international law as a whole. As we witness a redefinition of sovereignty as a responsibility of states towards the people and a shift to greater relevance of the individual in international law in general, it is a logical consequence that human rights have an impact on other areas of international law.