Contributions in Merlin

We analyze the financial integration of the new European Union (EU) member states' stock markets using the negative (positive) coexceedance variable that counts the number of large negative (large positive) returns on a given day across the countries. A similar analysis is performed for the old EU countries. We use a multinomial logit model to investigate how persistence, asset classes, and volatility are related to the coexceedance variables. We find that the effects differ (a) between negative and positive coexceedance variables (b) between old and new EU member states, and (c) before and after the EU enlargement in 2004, suggesting a closer connection of new EU stock markets to those in Western Europe.

Accounting is a key task in commercial networks. With the increasing number of IP-based services and mobility support, accounting needs to evolve towards an integrated, service-oriented accounting approach in a mobile environment. Therefore, this dissertation digest paper presents the Serviceoriented Tailored Accounting Configuration (STACO) architecture that enables a service-oriented accounting configuration management in a mobile, multi-domain networking environment. Additionally, it presents the Diameter flow accounting application as an extension to the Diameter protocol in order to integrate IP flow accounting into any Diameter-based infrastructure and to support an efficient transfer of IP flow records. Keywords–Accounting, Accounting Configuration, Mobility, IP Flow Accounting, Diameter, IPFIX.

Monitoring of Service Level Objectives (SLOs) determines an essential part of Service Level Agreement (SLA) management, since customers are to be reimbursed, if a providerfails to fulfil them. By automating this process, a timely detection of a violation is possible. The compliance approach must be flexible to adapt to potential changes, must be scalable with respect to the amount of data, and has to support multi-domain environments. This paper determines a Hosted Streaming Services scenario and defines relevant SLOs. Key requirements are derived, the respective architecture is designed, and the approach is implemented prototypically based on a generic auditing framework. Further-more, a new scheme is proposed that considers the degree and duration of SLO violations in calculating reimbursements.

Many applications operate on time-sensitive data. Some of these data are only valid for certain intervals (e.g., job-assignments, versions of software code), others describe temporal events that happened at certain points in time (e.g., a persons birthday). Until recently, the only way to incorporate time into Semantic Web models was as a data type property. Temporal RDF, however, considers time as an additional dimension in data preserving the semantics of time. In this paper we present a syntax and storage format based on named graphs to express temporal RDF. Given the restriction to preexisting RDF-syntax, our approach can perform any temporal query using standard SPARQL syntax only. For convenience, we introduce a shorthand format called t-SPARQL for temporal queries and show how t-SPARQL queries can be translated to standard SPARQL. Additionally, we show that, depending on the underlying data’s nature, the temporal RDF approach vastly reduces the number of triples by eliminating redundancies resulting in an increased performance for processing and querying. Last but not least, we introduce a new indexing approach method that can significantly reduce the time needed to execute time point queries (e.g., what happened on January 1st).

Accounting of Grid resource and service usage determines the central support activity for Grid systems to be adopted as a means for service-oriented computing in Dynamic Virtual Organizations (DVO). An all-embracing study of existing Grid accounting systems has revealed that these approaches focus primarily on technical precision, while they lack a foundation of appropriate economic accounting principles and the support for multi-provider scenarios or virtualization concepts. Consequently, a new, flexible, resource-based accounting model for DVOs was developed, combining technical and economic accounting by means of Activity-based Costing. Driven by a functional evaluation, this paper pursues a full-fledged evaluation of the new, generically applicable Grid accounting model. This is done for the specific environment of the Leibniz Supercomputing Centre (LRZ) in Garching, Germany. Thus, a detailed evaluation methodology and evaluation environment is outlined, leading to actual model-based cost calculations for a defined set of considered Grid services. The results gained are analyzed and respective conclusions on model applicability, optimizations, and further extensions are drawn.

Exceptions play an important role in conceptualizing data, especially when new knowledge is introduced or existing knowledge changes. Furthermore, real-world data often is contradictory and uncertain. Current formalisms for conceptualizing data like Description Logics rely upon first-order logic. As a consequence, they are poor in addressing exceptional, inconsistent and uncertain data, in particular when evolving the knowledge base over time. This paper investigates the use of Probabilistic Description Logics as a formalism for the evolution of ontologies that conceptualize real-world data. Different scenarios are presented for the automatic handling of inconsistencies during ontology evolution.

This paper concerns the pricing of American options with stochastic stopping time constraints expressed in terms of the states of a Markov process. Following the ideas of Menaldi et al., we transform the constrained into an unconstrained optimal stopping problem. The transformation replaces the original payoff by the value of a generalized barrier option. We also provide a Monte Carlo method to numerically calculate the option value for multidimensional Markov processes. We adapt the Longstaff-Schwartz algorithm to solve the stochastic Cauchy-Dirichlet problem related to the valuation problem of the barrier option along a set of simulated trajectories of the underlying Markov process.