reserve i,n,m,k,x for Nat,
  i1,i2 for Integer;
reserve a for Tuple of n,k-SD;
reserve aSub for Tuple of n,k-SD_Sub;

theorem Th16:
  SDSub_Add_Carry(0,k) = 0
proof
  set x = 0;
  Radix(k -' 1) <> x & -Radix(k-'1) <= 0 - 0 by POWER:34;
  hence thesis by Def3;
end;
