Matthias Ressel

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Concurrency control and group undo are important issues in the design of groupware, especially for interactive group editors. We present an improved version of an existing distributed algorithm for concurrency control that is based on operation transformations. Since the usability of the algorithm relies on its formal correctness, we present a set of(More)
User interface toolkits and higher-level tools built on top of them play an ever increasing part in developing graphical user interfaces. This paper describes the XIT system, a user interface development tool for the X Window System, based on Common Lisp, comprising user interface toolkits as well as high-level interactive tools organized into a layered(More)
To face prevailing problems with existing tools for interactively building graphical user interfaces we present a new object-oriented approach to implementing visual programming tools. This approach is employed by the user interface development environment XIT. It is based on the representation of knowledge for creating and manipulating interaction objects(More)
The Coxsackie B1 virus used was lethal for more than one-quarter of the Charles River CD-1 mice tested. Twice as many male animals succumbed. Castration increased the resistance of the highly susceptible male; by contrast, the susceptibility of the normally resistant female was increased. The degree of virulence of the virus and the effect of castration on(More)