Abstract
One-dimensional asymmetric exclusion model, in whichthe probabilities of hopping to the left and right are in general different, is studied. The boundaries are open; a particle is added at the left end and is removed at the right end. First, the mean field theory is applied to discuss the case ofarbitrary hopping probabilities. Second, exact solution is obtained for the case of equal hoppingprobability. Third, the properties of the model near the equal hopping probability case are investigated by the perturbation theory.It is found that the mean field theory does not give the correctdensity profile near the boundaries.