Critical behavior of nonequilibrium models with infinitely many   absorbing states
  I study the critical behavior of a two-dimensional dimer-trimer lattice model, introduced by K\"{o}hler and ben-Avraham [J. Phys. A {\bf 24}, L621 (1991)], for heterogeneous catalysis of the reaction $\frac{1}{2}A_{2}+\frac{1}{3}B_{3} \rightarrow AB$. The model possesses infinitely many absorbing states in which the lattice is saturated by adsorbed particles and reactions cease because only isolated vacancies are left. Results for various critical exponents show that the model exhibits the same critical behavior as directed percolation, contrary to earlier findings by K\"{o}hler and ben-Avraham. Together with several other studies, reviewed briefly in this article, this confirms that directed percolation is the generic universality class for models with infinitely many absorbing states. 
Iwan Jensen