Volume 5, Number 2, June 2004


Title:

Towards a Unified Model of Sociality in Multiagent Systems
 

Author & Affiliation:

Matthias Nickles, Michael Rovatsos, Wilfried Brauer, and Gerhard Weiß (Technical University Munich, Germany)

 
Abstract:

This paper presents communication systems (CS) as the first available uni ed model of socially intelligent systems defined in terms of communication structures. It combines the empirical analysis of communication in a social system with logical processing of social information to provide a general framework for computational components that exploit communication processes in multiagent systems. The two main contributions offered by this paper are as follows: First, a formal model of CS that is based on an improved version of expectation networks and their processing is presented. This formal model is based on a novel approach to the semantics of agent communication languages which contrasts with traditional approaches. Second, a number of CS-based applications are described which illustrate the enormous potential and impact of a CS-based perspective of socially intelligent systems.

   
Title:

Discovering, Recording and Handling Inconsistencies in Software Specifications

 
Author & Affiliation: Alexander Kozlenkov and Andrea Zisman (City University, UK)
 
Abstract:

Consistency management of software system specifications is an active research topic in the software engineering community. Development of large and complex systems involves the participation of many stakeholders producing multiple specifications at different levels of abstraction and, therefore,  may lead to inconsistencies in the specifications. In this paper we present a goal-based approach to consistency management of software system specifications, involving discovering, recording and handling inconsistencies. A powerful querying mechanism allows stakeholders to improve knowledge of the specifications. Our work focuses specifications in UML due to its highly popular use for supporting the object-oriented development process. The UML metamodel is represented as axioms that define goals. The axioms are dynamically bound to data from concrete specifications. Queries to the specifications and inconsistencies discovery are based on constructing and transforming paths representing sequences of concepts recorded during goal elaboration, and are executed by an inference engine based on an extended form of abduction. The handling process analyses the discovered inconsistencies using queries and rules, and applies decision trees to support resolution actions. A prototype tool has been implemented in order to evaluate and illustrate the approach. The approach has been evaluated in two case studies.  

 
Title: Towards Efficient Consistency Management for Informal Applications
 
Author & Affiliation:

Jan Scheffczyk, Uwe M. Borghoff, Peter Rodig, and Lothar Schmitz (Universitat der Bundeswehr, Germany)

 
Abstract: When a group of authors collaboratively edits interrelated documents, consistency problems occur almost immediately. Current document management systems (DMS) often lack adequate facilities for consistency management. We extend traditional DMS by explicit formal consistency rules. In contrast to many other approaches, we permit inconsistencies and present the consequences to the user, which is vital for flexible document management and information management. Based on a novel semantics our tools pinpoint inconsistencies precisely. In this paper we focus on a key issue: efficient techniques for consistency rule evaluation. Our strategy is known from databases: (1) static analysis characterizes and simplifies consistency rules, (2) at run-time rules are evaluated incrementally. The major differences to databases are that we consider informal documents and explicitly allow inconsistencies. Consequently, we do not have formal update descriptions and cannot rely on consistency prior to updates. This makes incremental consistency checking a real challenge. The contribution of this paper is to incrementally evaluate consistency rules in the presence of previous inconsistencies. We have implemented our techniques in a revision control system. Our experiments show that efficient incremental evaluation provides the key to making our approach viable.
 
Title: Application of Behavior-Preserving Transformations to Improve Non-Functional Properties of an Architecture Specification
 
Author & Affiliation: Lars Grunske and Einar Lück (University of Potsdam, Germany)
 
Abstract:

In particular for safety critical systems it is necessary to make sure that the non-functional properties imposed by a system architecture meet the corresponding requirements as early as possible. Therefore, appropriate architectural transformations have to be applied in the design phase in case the non-functional properties do not fulfill their requirements. As the selection and application of appropriate architectural transformations is a time consuming task and demands for personal effort, there is the idea to automate the architecture evolution process. In this paper, we outline a hypergraph-based approach towards automating the architecture evolution process and propose an algorithm that proves the behavioral equivalence of the architecture before and after a transformation.

 
Title: Categorization of Transparent-Motion Patterns Using the Projective Plane
 
Author & Affiliation:

Cicero Mota, Michael Dorr, Ingo Stuke, and Erhardt Barth (University of Lubeck, Germany)

 
Abstract:

Based on a new framework for the description of N transparent motions we categorize different types of transparent motion patterns. Confidence measures for the presence of all these classes of patterns are defined in terms of the ranks of the generalized structure tensor. To resolve the correspondence between the ranks of the tensors and the motion patterns, we introduce the projective plane as a new way of describing motion patterns. Transparent motions can occur in video sequences and are relevant for problems in human and computer vision. We show a few examples for how our framework can be applied to explain the perception of multiple-motion patterns and demonstrate a new illusion.

 
Title: Multiple-Motion-Estimation by Block-Matching Using Markov Random Fields
 
Author & Affiliation: Ingo Stuke, Til Aach, Erhardt Barth, and Cicero Mota (University of Lubeck, Germany)
 
Abstract:

This paper deals with the problem of estimating multiple motions at points where these motions are overlaid. We present a new approach that is based on block-matching and can deal with both transparent motions and occlusions. We derive a block-matching constraint for an arbitrary number of moving layers. We use this constraint to design a hierarchical algorithm that can distinguish between the occurrence of single, transparent, and occluded motions and can thus select the appropriate local motion model. The algorithm adapts to the amount of noise in the image sequence by use of a statistical confidence test. Robustness is further increased
with a regularization scheme based on Markov Random Fields. Performance is demonstrated on image sequences synthesized from natural textures with high levels of additive dynamic noise and on real video sequences.

 
Title: Dynamic Adaptive Quality-of-Service aware Resource Scheduling In Distributed Multimedia Systems
 
Author & Affiliation: Mohammad Riaz Moghal (University College of Engineering and Technology, Pakistan) and Mohammad Saleem Mian (University of Engineering and Technology, Pakistan)
 
Abstract:

The distributed multimedia systems services require Quality-of-Service aware optimum resource scheduling. In multimedia applications intermediate processing is done between distributed media sources and sinks. These applications need format conversion and mixing several media streams. All these tasks introduce some time-delay for the applications. Computer-machines at the intermediate stage are used to share tasks-load of overloaded end-users machines. Here the intermediate processing components (IPCs) are not subject to location restrictions. The problem of allocating these IPCs onto lightly loaded machines is to share loads of the over-loaded i.e., Bottleneck machines. The problem for star-shaped multimedia applications for single-host-satellite distributed architecture has already been discussed. This single-host system provides high bottleneck resource utilization and is one point failure system. We present new Double-Host-Satellite distributed architecture along with adaptive algorithms for the architectures. This double-host system provides least resource utilization compared to single-host system. Least resource utilization provides more free resources for new session of multimedia systems. Double host system is also fault tolerant system which means in
case of failure of one host, the other host can still provide service at some degraded quality. The present work addresses the problem of finding an adaptive optimized allocation of IPCs in order to achieve required QoS.