Probability of Incipient Spanning Clusters in Critical Two-Dimensional   Percolation
  The probability of simultaneous occurence of at least k spanning clusters has been studied by Monte Carlo simulations on the 2D square lattice at the bond percolation threshold Pc=1/2. The calculated probabilities for free boundary conditions and periodic boundary conditions are in a very good coincidence with the exact formulae developed recently by Cardy. 
L.N. Shchur and S.S. Kosyakov (Landau Institute for Theoretical   Physics, Chernogolovka, Russia)