theorem Th37:
  {} is_a_normal_form_wrt ReductionRel G
proof
  now
    set p = <*>FreeAtoms(G);
    given q being object such that
      A1: [p,q] in ReductionRel(G);
    q in field ReductionRel(G) by A1, RELAT_1:15;
    then q in FreeAtoms(G)* by Th30;
    then reconsider q as FinSequence of FreeAtoms(G) by FINSEQ_1:def 11;
    len p = len q + 1 by A1, Th35;
    hence contradiction;
  end;
  hence thesis by REWRITE1:def 5;
end;
