Before revision:  We apply the method to simulate interactions of an m-valent ligand with an n-valent cell-surface receptor . Simulation results show that  the rejection-free method is more efficient over wide parameter ranges than a related method that relies on rejection sampling .
After revision:  We apply the method to simulate simple models for ligand-receptor interactions . Simulation results show that the rejection-free method is more efficient over wide parameter ranges than a related method that relies on rejection sampling .