Computable de Finetti measures

We prove a computable version of de Finetti's theorem on exchangeable sequences of real random variables. As a consequence, exchangeable stochastic processes expressed in probabilistic functional programming languages can be automatically rewritten as procedures that do not modify non-local state. Along the way, we prove that a distribution on the unit interval is computable if and only if its moments are uniformly computable.Comment: 32 pages. Final journal version; expanded somewhat, with minor corrections. To appear in Annals of Pure and Applied Logic. Extended abstract appeared in Proceedings of CiE '09, LNCS 5635, pp. 218-23

Generalizing Hierarchical Parallelism

Since the days of OpenMP 1.0 computer hardware has become more complex, typically by specializing compute units for coarse- and fine-grained parallelism in incrementally deeper hierarchies of parallelism. Newer versions of OpenMP reacted by introducing new mechanisms for querying or controlling its individual levels, each time adding another concept such as places, teams, and progress groups. In this paper we propose going back to the roots of OpenMP in the form of nested parallelism for a simpler model and more flexible handling of arbitrary deep hardware hierarchies.Comment: IWOMP'23 preprin

Solving heterogeneity for a successful service market

Diese Dissertation ist im Kontext eines neuen Paradigmas im Software Engineering mit dem Namen On-The-Fly Computing entstanden. OTF Computing basiert auf der Idee von spezialisierten On-The-Fly Märkten. OTF Märkte haben unterschiedliche Eigenschaften und die Marktakteure in diesen Märkten benutzen verschiedene Modellierungstechniken für das Service Engineering. Diese Unterschiede resultieren in Heterogenität und erschweren deshalb die Ausführung von automatisierten Marktoperationen, da Servicebeschreibungen nicht automatisch miteinander verglichen werden können. Für das beschriebene Problem bietet diese Dissertation eine Lösung um einen erfolgreichen OTF Markt zu ermöglichen. Für die Vergleichbarkeit von Servicebeschreibungen in einem OTF Markt wird eine formale Zwischenrepräsentation (Kernsprache) eingeführt. Die Marktoperationen werden auf Basis der Kernsprache definiert, die die optimale Ausführung der automatisierten Marktoperationen in einem OTF Markt unterstützt. Der erste Beitrag dieser Dissertation ist der Ansatz Language Optimizer (LOpt). LOpt nutzt als Basis eine Kernsprache, die strukturelle, verhaltensbezogene und nicht-funktionale Serviceeigenschaften beinhaltet. LOpt konfiguriert diese Sprache basierend auf formalisierten Markteigenschaften und einer Wissensbasis mit Konfigurationsexpertise, um eine optimale Kernsprache zur Servicespezifikation im jeweiligen OTF Markt zu erstellen. Der zweite Beitrag dieser Dissertation ist die Anwendung des Model Transformation By-Example Ansatzes um den Marktakteuren ohne Expertise im Sprachdesign Transformationen von ihren proprietären Sprachen in die optimale Kernsprache zu ermöglichen. Der beschriebene Ansatz generiert Transformationen auf Basis von Beispielabbildungen zwischen Servicebeschreibungen zweier Sprachen. Dabei wird die Idee genetischer Algorithmen angewendet.This PhD thesis is written in the context of a new software development paradigm called On-The-Fly Computing. It is based on the idea of specialized service markets called On-The-Fly (OTF) markets. OTF markets have different properties and their participants use different modeling techniques to perform the activity of service engineering. Such differences result in heterogeneity in OTF markets and complicate the execution of automated market operations like service matching as service specifications cannot be automatically compared with each other. This PhD thesis proposes a solution to cope with the mentioned heterogeneity to foster the success of OTF markets and the OTF Computing paradigm. In order to achieve the comparability of specifications in an OTF market, a formal intermediate representation called core language is introduced. Automated market operations are defined on a core language that optimally supports the execution of these operations in this market. The first contribution of this PhD thesis is the approach language Optimizer (LOpt), which supports the systematic design of a service specification language optimal for the execution of automated market operations in an OTF market. LOpt uses a comprehensive core language covering various structural, behavioral, and non-functional service properties. LOpt performs a configuration of this language based on formalized market properties and a knowledge base containing the configuration expertise. The second contribution of this PhD thesis is the application of the Model Transformations By-Example technique to define transformations from proprietary specification languages of market actors to the optimal core language. The approach generates transformations based on example mappings between concrete specifications in both languages given by market actors. ...by Svetlana Arifulina, M.Sc. ; Thesis Supervisors: Prof. Dr. Gregor Engels and Jun. Prof. Dr. Heiko HamannTag der Verteidigung: 08.12.2016Universität Paderborn, Univ., Dissertation, 201