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The programming language aspects of a graphic simulation laboratory named ThingLab are presented. The design and implementation of ThingLab are extensions to SmaUtalk. In ThingLab, constraints are used to specify the relations that must hold among the parts of the simulation. The system is object-oriented and employs inheritance and part-whole hierarchies(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)
Constraint Logic Programming (CLP) is a general scheme for extending logic programming to include constraints. It is parameterized by D, the domain of the constraints. However, CLP(D) languages, as well as most other constraint systems, only allow the programmer to specify constraints that must hold. In many applications, such as interactive graphics, page(More)
Rank Xerox EuroPARC 61 Regent Street Cambridge CB2 lAB United Kingdom ABSTRACT We describe two systems ~hat use interactive computer-coutrolled video for shared awareness and casual communication. Polyscope lets users monitor a large number of video sources simultaneously. Observers are provided with a wiudow containing a collection of franle-grabbed bitmap(More)
We present a novel platform for supporting public deliberation on difficult decisions. ConsiderIt guides people to reflect on tradeoffs and the perspectives of others by framing interactions around pro/con points that participants create, adopt, and share. ConsiderIt surfaces the most salient pros and cons overall, while also enabling users to drill down(More)
Hierarchical Constraint Logic Programming languages extend Constraint Logic Programming to include constraint hierarchies. These languages provide both required constraints and default constraints of various strengths. In the original denition of HCLP, alternate solutions to a given constraint hierarchy were compared, and only the \best" solutions were(More)
B y helping travelers move from single-occupancy vehicles to public transit systems, communities can reduce traffic congestion as well as its environmental impact. Here, we describe our efforts to increase the satisfaction of current public transit users and help motivate more people to ride. OneBusAway (http://onebusaway.org), a suite of transit traveler(More)