
theorem Lemma20:
  for R,P being Relation st R misses P & P is symmetric holds
    R~ misses P
  proof
    let R,P be Relation;
    assume R misses P; then
A0: R~ misses P~ by LemmaAuxIrr;
    assume P is symmetric;
    hence R~ misses P by A0,RELAT_2:13;
  end;
