reserve X for set;

theorem Th2:
  for S being SigmaField of X, T being N_Measure_fam of S holds
  meet T in S & union T in S
proof
  let S be SigmaField of X, T be N_Measure_fam of S;
  T c= S by Def1;
  hence thesis by MEASURE1:22,def 5;
end;
