reserve n,m,k for Element of NAT,
  x,X for set,
  A1 for SetSequence of X,
  Si for SigmaField of X,
  XSeq for SetSequence of Si;
reserve Omega for non empty set,
  Sigma for SigmaField of Omega,
  ASeq for SetSequence of Sigma,
  P for Probability of Sigma;

theorem Th24:
  {} is thin of P
proof
  P.{} = 0 & {} in Sigma by PROB_1:4,VALUED_0:def 19;
  hence thesis by Def4;
end;
