
theorem Th39:
  for L be non empty ZeroStr for z0,z1 be Element of L holds len <%z0,z1%> <= 2
proof
  let L be non empty ZeroStr;
  let z0,z1 be Element of L;
  2 is_at_least_length_of <%z0,z1%>
  by Th38;
  hence thesis by ALGSEQ_1:def 3;
end;
