Abelian Cascade Dynamics in Bootstrap Percolation
  The culling process in Bootstrap Percolation is Abelian since the final stable configuration does not depend on the details of the updating procedure. An efficient algorithm is devised using this idea for the determination of the bootstrap percolation threshold in two dimension which takes $L^2$ time compared to the $L^3 \log L$ in the conventional method. A generalised Bootstrap Percolation allowing many particles at a site is studied where continuous phase transitions are observed for all values of the threshold parameter. Similar results are also obtained for the continuum Bootstrap Percolation model. 
S. S. Manna, (Satyendra Nath Bose National Centre for Basic Sciences,   Calcutta)