 Full-sweep arc consistency

Compute an arc-consistency closure by revising every directed constrained pair in complete sweeps until one sweep deletes nothing. The first sweep is unconditional. With $v$ variables, maximum constraint domain size $d$, and $e$ constrained pairs, at most $vd$ deletions permit at most $vd+1$ sweeps. At $O(d^2)$ per revision plus $O(v)$ per emptiness scan, a direct time complexity bound is $O((vd+1)(e{d}^2+v))$. AC-3 uses a work list to avoid scanning unrelated arcs after each local change.