From Local to Global Consistency* from Local to Global Consistency*
نویسنده
چکیده
In reasoning tasks involving the maintenance of consistent databases (so called "constraint net works") it is customary to enforce local consistency conditions in order to simplify the construc tion of a globally coherent model of the data. In this paper we present a relationship between the sizes of the variables' domains and the level of local consistency sufficient to ensure global con sistency. The results are presented for binary constraint networks first, and then are generalized to higher order constraints. An interesting result emerging from this relationship is that any rela tion on bi-valued variables which is not representable by a network of binary constraints cannot be represented by networks with hi9den variables. regardless of the number of hidden variables allowed. ·This work was supported in part by the National Science Foundation, Grant #00-88215522 and by the Air Force Office of Scientific Research. Grant#AFOSR-80-0136 while the author was visiting the cognitive systems lab at UCLA.
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