In this model we have , i.e., an AR(1) model. A close look at this AR(1) model immediately makes it clear that if , then the process blows up. Consider we have 6 particles in all and for simplicity each cell marked A and B has three particles in each. Hence from state  we can go to state  or , which means that when we move from  to , then the corresponding probability is , while for the movement from state  to  it is . Thus the transition matrix is of the form as shown  and if we draw the graph then we have the movement of the particle as given in Figure 6.2