Grand-Canonical Ensemble of Random Surfaces with Four Species of Ising   Spins
  The grand-canonical ensemble of dynamically triangulated surfaces coupled to four species of Ising spins (c=2) is simulated on a computer. The effective string susceptibility exponent for lattices with up to 1000 vertices is found to be $\gamma = - 0.195(58)$. A specific scenario for $c > 1$ models is conjectured. 
J.-P. Kownacki and A. Krzywicki