CONSTRAINT REASONING BASED ON INTERVAL ARITHMETIC - THE TOLERANCE PROPAGATION APPROACH

Interval constraint satisfaction (interval labeling) systems have traditionally been based on local Waltz filtering techniques that cannot in general determine global solutions. In contrast, this paper documents a related technique, tolerance propagation (TP), that generalizes the idea of numerical exact value propagation into interval propagation. In TP, consistency techniques based on the topology of the constraint net can be combined with techniques of interval arithmetic in a new fruitful way. In particular, by TP it is possible to determine global solutions for interval constraint satisfaction problems with arbitrary accuracy and without losing all attractions of simple local computations.