Bjørn N. Freeman-Benson

Learn More
Dynamic information collected as a software system executes can help software engineers perform some tasks on a system more effectively. To interpret the sizable amount of data generated from a system's execution, engineers require tool support. We have developed an off-line, flexible approach for visualizing the operation of an object-oriented system at(More)
SUMMARY The efficient satisfaction of constraints is essential to the performance of constraint-based user interfaces. In the past, most constraint-based user interfaces have used one-way rather than multi-way constraints because of a widespread belief that one-way constraints were more efficient. In this paper we argue that many user interface construction(More)
Constraints describe relations that must be maintained, and provide a useful tool for such applications as interactive simulations, algorithm animation, and graphical user interface construction. We describe a major overhaul and extension to the constraint satisfaction mechanism in ThingLab, a constraint-oriented simulation laboratory written in the(More)
Ultraviolet is a constraint satisfaction algorithm intended for use in interactive graph-ical applications. It is capable of solving constraints over arbitrary domains using local propagation , and inequality constraints and simultaneous linear equations over the reals. To support this, Ultraviolet is a hybrid algorithm that allows diierent subsolvers to be(More)
Constraints are declarative statements of relations among elements of the language's computational domain, e.g., integers, booleans, strings, and other objects. Orthogonally, the tools of object-oriented programming, including encapsulation, inheritance, and dynamic message binding, provide important mechanisms for extending a language's domain. Although(More)
Kaleidoscope is an object-oriented language being designed to integrate the traditional <italic>imperative</italic> object-oriented paradigm with the less traditional <italic>declarative</italic> constraint paradigm. Imperative state changes provide sequencing while declarative constraints provide object relations. A <italic>variables as streams</italic>(More)
ENVY/Constraints is an IBM/Smalltalk library that provides a constraint satisser and a collection of useful constraints, targeted at developing interactive graphical user interfaces. The solver supports multi-way constraints and constraint hierarchies. It uses a hybrid algorithm, combining local propagation with pluggable cycle solvers, allowing constraints(More)
ThingLab II is an object-oriented constraint programming system designed specifically for interactive user interface construction and implemented in Smalltalk-80 For constraints to be effective in building user interfaces, they must not impede the responsiveness of the user interface either at run time or during construction. The necessary speed is attained(More)