The conclusion is that the unique equilibrium leads to a non profitable manipulation, and social surplus is increased by the possibility of dropping bids, if the level of takeover activity is high; on the contrary, the unique equilibrium results in.

Based on the earthbound inertial coordinate system and the kinetic energy theorem and under the finite mass of recovery body condition, equations for calculating the snatch force are developed,and then on the assumption of infinite mass of recovery body,the same equations for calculating the snatch force as that of Refs [1] and [2] are obtained.