TRANSFORMATION PROPERTIES OF THREE SETS OF CLOSED TIME PATH GREEN''S FUNCTIONS
三套闭路格林函数的变换关系

In this article, we derived the transformations among three sets of elosed time path Green's functions and some calculation rules, from which a general definition of arbitrary multipoint retarded and advanced Green's functions follows naturally. Some algebraic identities among multipoint functions have shown to be the consequences of the property WJ+,J-](J+=J-=J)=0 for the generating functional on the closed time path.