let D be non empty set ; for F being PartFunc of D,REAL
for X being set st dom (F | X) is finite holds
FinS (F | X),X = FinS F,X
let F be PartFunc of D,REAL ; for X being set st dom (F | X) is finite holds
FinS (F | X),X = FinS F,X
let X be set ; ( dom (F | X) is finite implies FinS (F | X),X = FinS F,X )
A1:
(F | X) | X = F | X
by RELAT_1:101;
assume A2:
dom (F | X) is finite
; FinS (F | X),X = FinS F,X
then
FinS F,X,F | X are_fiberwise_equipotent
by Def14;
hence
FinS (F | X),X = FinS F,X
by A2, A1, Def14; verum