Urban emergency intelligent decision system based on variable precision graded rough set on two universes

In recent years, different kinds of rough set models on two universes have been given. In this paper a variable precision graded rough set model based on two distinct but related universes (VPGRSTU) is proposed. We determine the scope of the grade from the absolute quantitative point of view, and the precision of ⁿ can be changed with user requirements. We introduce an algorithm to compute the new lower and upper approximations in VPGRSTU. Furthermore, a method to measure roughness of VPGRSTU is given. The method also can be used to compute the lower and upper approximations. An algorithm based on matrix is proposed to realize above method. Finally, several examples are employed to demonstrate the VPGRSTU and the theory in this paper. At last we build urban emergency intelligent decision system based on VPGRSTU.