Abstract
This paper is concerned with the optimal stopping problem for discrete time multiparameter stochastic processes with the index set Nd . The definition of a multiple stopping point and a multiple tactic, and the formulation of a multiple stopping problem for multiparameter stochastic processes are provided. The notion of the accessibility of a multiple stopping point, the conditional qualitative independence and the stability of a multiple multiparameter filtration are introduced. The relation between the accessibility of a multiple stopping point and the structure of a multiple multiparameter filtration, and especially, in the case d = 2, the relation between the predictability of a multiple stopping point and the structure of a multiple multiparameter filtration are explored.