The SeqBin Constraint Revisited
  We revisit the SeqBin constraint. This meta-constraint subsumes a number of
important global constraints like Change, Smooth and IncreasingNValue. We show
that the previously proposed filtering algorithm for SeqBin has two drawbacks
even under strong restrictions: it does not detect bounds disentailment and it
is not idempotent. We identify the cause for these problems, and propose a new
propagator that overcomes both issues. Our algorithm is based on a connection
to the problem of finding a path of a given cost in a restricted $n$-partite
graph. Our propagator enforces domain consistency in O(nd^2) and, for special
cases of SeqBin that include Change, Smooth and IncreasingNValue, in O(nd)
time.
