In this paper, according to inversion set and its topological space definition, we studied some mathematical definition and their relevant theorem of decision theory, and apply theory to practice.

A unified definition for damping torque coefficient of synchronous machines is proposed in this paper according to the principle of synthetic damping coefficients deduced from the Lyapunov Theorem.

In this paper, We give a equal definition of strong stopping point, and obtain a stopping theorem for two-parameter martingales to strong stopping point.