Global Consistency in Interval Algebra Networks: Tractable Subclasses

Global consistency is an important property in binary constraint satisfaction problems. It implies minimality in the sense that the edges contain all and only the labels that can participate in a global solution, which, for instance, is an important property in querying temporal knowledge bases. Another, computational, advantage of a globally consistent network is that nding a solution can be done in a backtrack-free manner. In this paper, we propose two new subclasses of the interval algebra for which path-consistency is suucient to ensure global consistency, i.e. path-consistency applied to any network expressed in either of the two subclasses leads to a globally consistent network. One of the two subclasses covers more than 60% of the ORD-Horn subclass.

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