  We study opinion formation in a population that consists of leftists,
centrists, and rightist. In an interaction between neighboring agents, a
centrist and a leftist can become both centrists or leftists (and similarly for
a centrist and a rightist). In contrast, leftists and rightists do not affect
each other. The initial density of centrists rho_0 controls the evolution. With
probability rho_0 the system reaches a centrist consensus, while with
probability 1-rho_0 a frozen population of leftists and rightists results. In
one dimension, we determine this frozen state and the opinion dynamics by
mapping the system onto a spin-1 Ising model with zero-temperature Glauber
kinetics. In the frozen state, the length distribution of single-opinion
domains has an algebraic small-size tail x^{-2(1-psi)} and the average domain
size grows as L^{2*psi}, where L is the system length. The approach to this
frozen state is governed by a t^{-psi} long-time tail with psi-->2*rho_0/pi as
rho_0-->0.
