Title: Boolean dimension and tree-width,
Abstract: The dimension is a key measure of complexity of partially ordered sets. Small
dimension allows succinct encoding. Indeed if $P$ has dimension $d$, then to
know whether $x \leq y$ in $P$ it is enough to check whether $x\leq y$ in each
of the $d$ linear extensions of a witnessing realizer. Focusing on the encoding
aspect Nešetřil and Pudlák defined a more expressive version of
dimension. A poset $P$ has boolean dimension at most $d$ if it is possible to
decide whether $x \leq y$ in $P$ by looking at the relative position of $x$ and
$y$ in only $d$ permutations of the elements of $P$. We prove that posets with
cover graphs of bounded tree-width have bounded boolean dimension. This stays
in contrast with the fact that there are posets with cover graphs of tree-width
three and arbitrarily large dimension. This result might be a step towards a
resolution of the long-standing open problem: Do planar posets have bounded
boolean dimension?