  We extend the mathematical model proposed by Ottaviano-Tabuchi-Thisse (2002)
to a multi-regional case and investigate the stability of the homogeneous
stationary solution of the model in a one-dimensional periodic space. When the
number of regions is two and three, the homogeneous stationary solution is
stable under sufficiently high transport cost. On the other hand, when the
number of regions is a multiple of four, the homogeneous stationary solution is
unstable under any values of the transport cost.
