  The at-most-k constraint is ubiquitous in combinatorial problems, and
numerous SAT encodings are available for the constraint. Prior experiments have
shown the competitiveness of the sequential-counter encoding for k $>$ 1, and
have excluded the parallel-counter encoding, which is more compact that the
binary-adder encoding, from consideration due to its incapability of enforcing
arc consistency through unit propagation. This paper presents an experiment
that shows astounding performance of the binary-adder encoding for the
at-most-k constraint.
