Key to implementation: when 𝑝𝑡(𝑥)is changed, propagate the changed part to the related pointers of 𝑥
Pointer Flow Graph (PFG) of a program is a directed graph that expresses how objects flow among the pointers in the program.
Node: Pointer = V ⋃ (O × F)
Edges: Pointer × Pointer
b = new T();