  We investigate the complexity of local search based on steepest ascent. We
show that even when all variables have domains of size two and the underlying
constraint graph of variable interactions has bounded treewidth (in our
construction, treewidth 7), there are fitness landscapes for which an
exponential number of steps may be required to reach a local optimum. This is
an improvement on prior recursive constructions of long steepest ascents, which
we prove to need constraint graphs of unbounded treewidth.
