 Let m = Dion, t = a pre-operation time, r1 = the region occupied by Dion at t, and r2 = the region corresponding to all of Dion except for his right foot at t. If DAUP were correct, then Theon would exist, for it would just be the proper part of Dion that occupies r2 at t. Van Inwagen denies the existence of Theon, so he rejects the general principle as well. (For more on DAUP and material constitution, see van Inwagen 1981, Olson 1995, and Parsons 2004.)