Algorithms and Algorithm Analysis of Logical Difference Operation of Grade Upper Approximation Operator and Variable Precision Lower Approximation Operator

This paper is to construct new operation of approximation operators, and explore its calculation. First it proposes logical difference operation of grade upper approximation operator and variable precision lower approximation operator. Then regular algorithm and structural algorithm are proposed and analyzed, and furthermore it obtains an important conclusion that structural algorithm has advantages in space complexity. Finally a medical example is given to illustrate the new operation and its algorithms.