reserve k,m,n for Nat,
  i1,i2,i3 for Integer,
  e for set;
reserve i,k,m,n,p,x,y for Nat;

theorem Th10:
  e in k-SD implies e is Integer
proof
  assume e in k-SD;
  then ex t be Element of INT st e = t & t <= Radix(k)-1 & t >= -Radix(k)+1;
  hence thesis;
end;
