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)
Providing undo functionality in groupware has been identified as an important, but difficult problem. Existing solutions show deficiencies like lacking generality, being too complex, being inefficient, or failing to yield acceptable results in common situations. In this paper we describe a new approach which reduces local group undo to a(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)
Um bestehende Interhospitaltransfersysteme zu entlasten, wurde in Bayern 2009 ein Verlegungsarzt (VA) eingeführt. Ziel war es, Patienten, die einer ärztlichen Überwachung und Therapie, aber keiner intensivmedizinischen Behandlung bedürfen, zu transportieren. In einer retrospektiven Analyse wurden neben logistischen Daten (Einsatzzeit, Dauer, Ort,(More)