  We provide a new upper bound for traveling salesman problem (TSP) in cubic
graphs, i.e. graphs with maximum vertex degree three, and prove that the
problem for an $n$-vertex graph can be solved in $O(1.2553^n)$ time and in
linear space. We show that the exact TSP algorithm of Eppstein, with some minor
modifications, yields the stated result. The previous best known upper bound
$O(1.251^n)$ was claimed by Iwama and Nakashima [Proc. COCOON 2007].
Unfortunately, their analysis contains several mistakes that render the proof
for the upper bound invalid.
