Typo in formula. In Section 7.3, in the formula for pheromone evaporation, add a plus operator (+) between the evaporated amount of pheromones and the newly added ones, i.e., read
$\tau_{ij}^{t+1}=(1\rho)\tau_{ij}^{t}+\Delta T_{ij}$
instead of
$\tau_{ij}^{t+1}=(1\rho)\tau_{ij}^{t}~\Delta T_{ij}$
[Thanks to Dietmar Schreiner, Institute of Computer Languages, Vienna University of Technology]
