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 Th28:
  Sigma c= COM(Sigma,P)
proof
  reconsider C={} as thin of P by Th24;
  let A be object such that
A1: A in Sigma;
   reconsider AA=A as set by TARSKI:1;
  A = AA \/ C;
  hence thesis by A1,Def5;
end;
