theorem Th2: :: singleUsedF:
  UsedI*Loc (l .--> i) = UsedInt*Loc i
proof rng(l .--> i) = {i} by FUNCOP_1:8;
  hence UsedI*Loc(l .--> i) =  union { UsedInt*Loc i1 : i1 in {i} }
       .= UsedInt*Loc i from SUBSET_1:sch 5;
end;
