theorem Th10:
  dom((Partial_Sums F).n) = meet{dom(F.k) where k is Element of NAT : k <= n}
proof
  dom((Partial_Sums R_EAL F).n) = meet{dom((R_EAL F).k) where k is Element
of NAT : k <= n} & (Partial_Sums R_EAL F).n = (R_EAL(Partial_Sums F)).n by Th7
,Th9,MESFUNC9:28;
  hence thesis;
end;
