let T be non empty RelStr ; for A being Subset of T st T is filled holds
for n being Element of NAT holds Fint A,(n + 1) c= Fint A,n
let A be Subset of T; ( T is filled implies for n being Element of NAT holds Fint A,(n + 1) c= Fint A,n )
assume A1:
T is filled
; for n being Element of NAT holds Fint A,(n + 1) c= Fint A,n
let n be Element of NAT ; Fint A,(n + 1) c= Fint A,n
((Fint A) . n) ^i = Fint A,(n + 1)
by Def4;
hence
Fint A,(n + 1) c= Fint A,n
by A1, FIN_TOPO:28; verum