Filtering Algorithms Based on the Word-RAM Model

The Word-RAM is a model of computation that takes into account the capacity of a computer to manipulate a word of w bits with a single instruction. Many modern constraint solvers use a bitset data structure to encode the values contained in the variable domains. Using the algorithmic techniques developed for the Word-RAM, we propose new filtering algorithms that can prune Opwq values from a domain in a single instruction. Experiments show that on a processor with w “ 64, the new filtering algorithms that enforce domain consistency on the constraints A ` B “ C, |A B| “ C and ALL-DIFFERENT can offer a speed up of a factor 10.