Collaborative Object Groups are abstractions that facilitate programming of collaborative systems considerably. In this paper, we argue that operational transformation should be offered to programmers as a part of services provided by a Collaborative Object Group platform and describe how to integrate operational transformation in such a platform. We also explain how operational transformation ...

We combine the methodology of Plotkin-style operational semantics with graph transformation concepts in order to specify the operational semantics of diagram languages.

The cost and schedule required to design and develop modern computer based systems has grown dramatically over the past decade. Advanced system engineering development methods and automation techniques are required to manage the complexity inherent in the design of large complex computer based systems to provide an efficient means for evaluating various requirements options. OML is an approach,...

For Gerhard Jäger, in honor of his 60 th birthday. Let me begin with a few personal words of appreciation, since Gerhard Jäger is one of my most valued friends and long time collaborators. It's my pleasure to add my tribute to him for his outstanding achievements and leadership over the years, and most of all for having such a wonderful open spirit and being such a fine person. I first met Gerh...

A procedure’s client must satisfy its precondition— that is, reach a state in which the procedure may be called. Preconditions describe the state that needs to be reached, but not how to reach it. We use static analysis to infer the sequence of operations a variable goes through before being used as a parameter: “In parseProperties(String xml), the parameter xml normally stems from getPropertie...

Over the years, Logic Programming has proved to be a good and natural tool for expressing, querying and manipulating explicit knowledge in many areas of computer science. However, it is not so easy to use in dynamic environments. Evolving Logic Programs (EVOLP) are an elegant and powerful extension of Logic Programming suitable for Multi-Agent Systems, planning and other uses where information ...

Theoretical research has spent some years facing the problem of how to represent and provide semantics to updates of logic programs. This problem is relevant for addressing highly dynamic domains with logic programming techniques. Two of the most recent results are the definition of the refined stable and the well founded semantics for dynamic logic programs that extend stable model and well fo...