About the problem formulation

[zzt007]

Hi, thanks for your great job! There is a problem bother me a lot , which about the paper's problem formulation.

N_0 means the total count of tracked objects in the sequence, and the T_h means the observation horizon. However, during the sequence length, the N_0 may change, and here is appears to be a fixed value? In other words, the lifetime of the tracked object may be less than the sequence length. So I don't know how to due with these 'variables' in my model. Looking forward to your early reply!