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Kosiuczenko P.,Institute of Information Systems
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2010

The evaluation of post-conditions requires the computation of old attribute values. Until recently, existing computation methods were not efficient in terms of time- and space-complexity. Moreover they were applicable only to a restricted form of post-conditions. Recently a new algorithm was proposed to overcome those deficiencies. In this paper, an abstract machine corresponding to this algorithm is defined. Its transitions simulate steps of object-oriented systems and preserve an invariant implying properties needed to compute old attribute values. The machine is based on a kind of structure called here sufficiently persistent, as opposed to persistent and partially persistent structures. A space-bound on the structure size is given. It is also demonstrated that methods which do not have post-conditions can be abstracted away. © 2010 Springer-Verlag Berlin Heidelberg.


Kosiuczenko P.,Institute of Information Systems
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2012

This paper examines the effect of class diagram transformation on state machines, a subject which has not been properly investigated. It is demonstrated that structural relations between states can be interpreted as a logical relation between the corresponding formulas and the preservation of the latter corresponds to the preservation of state machine structure. A sufficient condition, based on the form of the underlying transformation and proofs, is provided which guarantees that class structure transformation preserves the structure of state machines. The goal is to automatically transform state-invariants and to identify those state machines which need to be manually transformed after class model redesign. © 2012 Springer-Verlag.


Schobel A.,Institute for Numerical and Applied Mathematics | Schwarze S.,Institute of Information Systems
NETNOMICS: Economic Research and Electronic Networking | Year: 2013

We present a game-theoretic model for the line planning problem in public transportation, in which each line acts as player. Each player aims to minimize its own delay, which is dependent on the traffic load along its edges. We show that there exists a line plan at equilibrium, which minimizes the probability of delays of the transportation system. This result is achieved by showing that a potential function exists. Numerical results using close-to-real world data in the LinTim framework clearly show that our method indeed produces delay-resistant line concepts. © 2013 Springer Science+Business Media New York.


Kosiuczenko P.,Institute of Information Systems
Software and Systems Modeling | Year: 2013

The Object Constraint Language (OCL) is a high-level, object-oriented language for contractual system specifications. Despite its expressivity, OCL does not provide primitives for a compact specification of invariability. In this paper, problems with invariability specification are listed and some weaknesses of existing solutions are pointed out. The question of invariability specification is addressed and a simple but expressive extension of OCL is proposed. It allows a view-oriented specification of invariability constraints, whereby we restrict the notion of view to reducts based on order-sorted algebras. The semantics of this extension is defined in terms of standard OCL. © 2011 The Author(s).


Dustdar S.,Vienna University of Technology | Guo Y.,Imperial College London | Satzger B.,Institute of Information Systems | Truong H.-L.,Vienna University of Technology
IEEE Internet Computing | Year: 2011

Cloud computing's success has made on-demand computing with a pay-as-you-go pricing model popular. However, cloud computing's focus on resources and costs limits progress in realizing more flexible, adaptive processes. The authors introduce elastic processes, which are based on explicitly modeling resources, cost, and quality, and show how they improve on the state of the art. © 2011 IEEE.

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