  In this paper, we describe Compact-Table (CT), a bitwise algorithm to enforce
Generalized Arc Consistency (GAC) on table con- straints. Although this
algorithm is the default propagator for table constraints in or-tools and
OscaR, two publicly available CP solvers, it has never been described so far.
Importantly, CT has been recently improved further with the introduction of
residues, resetting operations and a data-structure called reversible sparse
bit-set, used to maintain tables of supports (following the idea of tabular
reduction): tuples are invalidated incrementally on value removals by means of
bit-set operations. The experimentation that we have conducted with OscaR shows
that CT outperforms state-of-the-art algorithms STR2, STR3, GAC4R, MDD4R and
AC5-TC on standard benchmarks.
