004 Datenverarbeitung; Informatik
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Background: The development of bioinformatics databases, algorithms, and tools throughout the last years has lead to a highly distributedworld of bioinformatics services. Without adequatemanagement and development support, in silico researchers are hardly able to exploit the potential of building complex, specialized analysis processes from these services. The Semantic Web aims at thoroughly equipping individual data and services with machine-processable meta-information, while workflow systems support the construction of service compositions. However, even in this combination, in silico researchers currently would have to deal manually with the service interfaces, the adequacy of the semantic annotations, type incompatibilities, and the consistency of service compositions. Results: In this paper, we demonstrate by means of two examples how Semantic Web technology together with an adequate domain modelling frees in silico researchers from dealing with interfaces, types, and inconsistencies. In Bio-jETI, bioinformatics services can be graphically combined to complex services without worrying about details of their interfaces or about type mismatches of the composition. These issues are taken care of at the semantic level by Bio-jETI’s model checking and synthesis features. Whenever possible, they automatically resolve type mismatches in the considered service setting. Otherwise, they graphically indicate impossible/incorrect service combinations. In the latter case, the workflow developermay either modify his service composition using semantically similar services, or ask for help in developing the missing mediator that correctly bridges the detected type gap. Newly developed mediators should then be adequately annotated semantically, and added to the service library for later reuse in similar situations. Conclusion: We show the power of semantic annotations in an adequately modelled and semantically enabled domain setting. Using model checking and synthesis methods, users may orchestrate complex processes from a wealth of heterogeneous services without worrying about interfaces and (type) consistency. The success of this method strongly depends on a careful semantic annotation of the provided services and on its consequent exploitation for analysis, validation, and synthesis. We are convinced that these annotations will become standard, as they will become preconditions for the success and widespread use of (preferred) services in the Semantic Web
Pattern matching is a well-established concept in the functional programming community. It provides the means for concisely identifying and destructuring values of interest. This enables a clean separation of data structures and respective functionality, as well as dispatching functionality based on more than a single value. Unfortunately, expressive pattern matching facilities are seldomly incorporated in present object-oriented programming languages. We present a seamless integration of pattern matching facilities in an object-oriented and dynamically typed programming language: Newspeak. We describe language extensions to improve the practicability and integrate our additions with the existing programming environment for Newspeak. This report is based on the first author’s master’s thesis.
Business process management aims at capturing, understanding, and improving work in organizations. The central artifacts are process models, which serve different purposes. Detailed process models are used to analyze concrete working procedures, while high-level models show, for instance, handovers between departments. To provide different views on process models, business process model abstraction has emerged. While several approaches have been proposed, a number of abstraction use case that are both relevant for industry and scientifically challenging are yet to be addressed. In this paper we systematically develop, classify, and consolidate different use cases for business process model abstraction. The reported work is based on a study with BPM users in the health insurance sector and validated with a BPM consultancy company and a large BPM vendor. The identified fifteen abstraction use cases reflect the industry demand. The related work on business process model abstraction is evaluated against the use cases, which leads to a research agenda.
Internetbasierte Informatiksysteme beeinflussen in steigendem Maße Situationen in unterschiedlichen Lebensbereichen. Kompetenzen zur Verwendung von Internetanwendungen und -diensten müssen explizit erworben werden, weil damit ein notwendiger Einblick in nicht beobachtbare Abläufe und nicht offen sichtbare Strukturen verbunden ist. Bisher gibt es Vorschläge für die Gestaltung schulischer Lehr-Lernprozesse zu ausgewählten Teilaspekten des Internets. Es fehlt eine systematische Analyse des Bildungsbedarfs und ein daraus resultierendes Unterrichtsmodell. In dieser Arbeit wird ein Gesamtkonzept für den Informatikunterricht in der Sekundarstufe II vorgestellt, das zu zielgerichteter und verantwortungsvoller Anwendung des Internets beiträgt. Die vorliegende Arbeit umfasst den Prozess von der Analyse erforderlicher Kompetenzen bis zur Realisierung von Lehr-Lernprozessen im Informatikunterricht in der Sekundarstufe II. Es werden der Beitrag der Informatik zu identifizierten Kompetenzen untersucht und Bildungsanforderungen bestimmt. Bildungsempfehlungen und Forschungsergebnisse zu erfolgreichen Unterrichtseinheiten werden im Hinblick auf die Bildungsziele analysiert. Der Informatikunterricht unterstützt die Kompetenzentwicklung zu internetbasierten digitalen Medien. Es wird die Entwicklung eines Unterrichtsmodells zu Internetworking beschrieben. Dazu wird der Ansatz der Didaktischen Systeme untersucht, weiter entwickelt und auf den Bereich Internetworking übertragen. Der theoretische Ansatz wird dazu in vier Unterrichtsprojekten zu Internetworking in der Praxis realisiert. Beziehungen zwischen Fachkonzepten zu Internetworking werden untersucht und durch Wissensstrukturen zur Planung von Unterrichtsprojekten eingesetzt und in der Praxis erprobt. Die Beschreibung von Lernaktivitäten erfolgt auf der Basis von Aufgabenklassen, die das notwendige Wissen zur Bearbeitung einer Aufgabenstellung repräsentieren. Auf der Grundlage des Ablaufs der Aufgabenbearbeitung werden Eigenschaften von Aufgaben beschrieben und zu deren Gestaltung nutzbar gemacht. Bisher nicht durchführbare Tätigkeiten im Unterricht werden durch die Entwicklung der Lernsoftware Filius ermöglicht. Die Reduktion der komplexen Wirklichkeit durch Simulation realer internetbasierter Informatiksysteme und die Auswahl geeigneter Sichten auf den Untersuchungsgegenstand werden mit Ergebnissen der Informatikdidaktik begründet. Unterrichtsprojekte zu den Zielen werden durchgeführt, um Lehr-Lernprozesse zu erkunden und das entwickelte Didaktische System zu erproben. Ausgehend von der theoretischen Fundierung erfolgt die praktische Realisierung von Lehr-Lernprozessen. Zur Erprobung im Informatikunterricht der Sekundarstufe II in Nordrhein-Westfalen werden Minimalziele aufgrund der Lehrvorgaben bestimmt. Die methodische Gestaltung in der Erprobung erfolgt unter Berücksichtigung der Vorgaben für den Informatikunterricht und allgemeinen Anforderungen der Fachdidaktik. Handlungsorientierte Unterrichtsmittel werden ausgewählt und in der Praxis zur Untersuchung der Lehr-Lernprozesse verwendet. Im Unterricht identifizierte Lernschwierigkeiten führen zur Modifikation der Wissensstrukturen und werden im Entwicklungsprozess von Filius berücksichtigt. Die Erkenntnisse aus Unterrichtsprojekten werden genutzt, um zu bestimmen, zu welchen Aufgabenklassen weitere Aufgaben erforderlich sind und inwieweit das aus den identifizierten Merkmalen abgeleitete Vorgehen zur Entwicklung niveaubestimmender Aufgaben genutzt werden kann. Die Erprobungen bestätigen die Tragfähigkeit des Didaktischen Systems Internetworking und leisten mit der Implementierung in der Praxis einen Beitrag zur Untersuchung von Kompetenzentwicklung im Informatikunterricht. Mit dem Didaktischen System Internetworking wird ein theoretisch fundiertes und empirisch erprobtes Unterrichtsmodell zur Entwicklung von Kompetenzen zur Einrichtung und Anwendung internetbasierter Informatiksysteme beschrieben.
Data obtained from foreign data sources often come with only superficial structural information, such as relation names and attribute names. Other types of metadata that are important for effective integration and meaningful querying of such data sets are missing. In particular, relationships among attributes, such as foreign keys, are crucial metadata for understanding the structure of an unknown database. The discovery of such relationships is difficult, because in principle for each pair of attributes in the database each pair of data values must be compared. A precondition for a foreign key is an inclusion dependency (IND) between the key and the foreign key attributes. We present with Spider an algorithm that efficiently finds all INDs in a given relational database. It leverages the sorting facilities of DBMS but performs the actual comparisons outside of the database to save computation. Spider analyzes very large databases up to an order of magnitude faster than previous approaches. We also evaluate in detail the effectiveness of several heuristics to reduce the number of necessary comparisons. Furthermore, we generalize Spider to find composite INDs covering multiple attributes, and partial INDs, which are true INDs for all but a certain number of values. This last type is particularly relevant when integrating dirty data as is often the case in the life sciences domain - our driving motivation.
This thesis presents methods for automated synthesis of flexible chip multiprocessor systems from parallel programs targeted at FPGAs to exploit both task-level parallelism and architecture customization. Automated synthesis is necessitated by the complexity of the design space. A detailed description of the design space is provided in order to determine which parameters should be modeled to facilitate automated synthesis by optimizing a cost function, the emphasis being placed on inclusive modeling of parameters from application, architectural and physical subspaces, as well as their joint coverage in order to avoid pre-constraining the design space. Given a parallel program and a set of an IP library, the automated synthesis problem is to simultaneously (i) select processors (ii) map and schedule tasks to them, and (iii) select one or several networks for inter-task communications such that design constraints and optimization objectives are met. The research objective in this thesis is to find a suitable model for automated synthesis, and to evaluate methods of using the model for architectural optimizations. Our contributions are a holistic approach for the design of such systems, corresponding models to facilitate automated synthesis, evaluation of optimization methods using state of the art integer linear and answer set programming, as well as the development of synthesis heuristics to solve runtime challenges.
The difference-list technique is described in literature as effective method for extending lists to the right without using calls of append/3. There exist some proposals for automatic transformation of list programs into differencelist programs. However, we are interested in construction of difference-list programs by the programmer, avoiding the need of a transformation step. In [GG09] it was demonstrated, how left-recursive procedures with a dangling call of append/3 can be transformed into right-recursion using the unfolding technique. For simplification of writing difference-list programs using a new cons/2 procedure was introduced. In the present paper, we investigate how efficieny is influenced using cons/2. We measure the efficiency of procedures using accumulator technique, cons/2, DCG’s, and difference lists and compute the resulting speedup in respect to the simple procedure definition using append/3. Four Prolog systems were investigated and we found different behaviour concerning the speedup by difference lists. A result of our investigations is, that an often advice given in the literature for avoiding calls append/3 could not be confirmed in this strong formulation.
A deterministic cycle scheduling of partitions at the operating system level is supposed for a multiprocessor system. In this paper, we propose a tool for generating such schedules. We use constraint based programming and develop methods and concepts for a combined interactive and automatic partition scheduling system. This paper is also devoted to basic methods and techniques for modeling and solving this partition scheduling problem. Initial application of our partition scheduling tool has proved successful and demonstrated the suitability of the methods used.
In the most abstract definition of its operational semantics, the declarative and concurrent programming language CHR is trivially non-terminating for a significant class of programs. Common refinements of this definition, in closing the gap to real-world implementations, compromise on declarativity and/or concurrency. Building on recent work and the notion of persistent constraints, we introduce an operational semantics avoiding trivial non-termination without compromising on its essential features.