theorem Th49:
  for K being non empty doubleLoopStr,
      v being Valuation of K holds
  K is having_valuation implies 0.K in NonNegElements v
  proof
    let K be non empty doubleLoopStr,
    v be Valuation of K;
    assume K is having_valuation;
    then v.0.K = +infty by Def8;
    hence thesis;
  end;
