Kinetics of Coalescence, Annihilation, and the q-State Potts Model in   One Dimension
  The kinetics of the q-state Potts model in the zero temperature limit in one dimension is analyzed exactly through a generalization of the method of empty intervals, previously used for the analysis of diffusion-limited coalescence, A+A->A. In this new approach, the q-state Potts model, coalescence, and annihilation (A+A->0) all satisfy the same diffusion equation, and differ only in the imposed initial condition. 
Thomas Masser and Daniel ben Avraham