(Subscript[f, v]^′)(t)={((-(Underoverscript[∐, (i=v-1), 0])(Subscript[f, i])(t))   ◦   y   ◦   (-(Underoverscript[∐, (i=v+1), n])(Subscript[f, i])(t))when   layering   policy   is   additive             (((-(Underoverscript[∐, (i=v-1), 0])(Subscript[f, i])(t)) )^(-1))  ◦   y   ◦   (((-(Underoverscript[∐, (i=v+1), n])(Subscript[f, i])(t)))^(-1))when   layering   policy   is   multiplicative.)