reserve X for non empty set,
  Y for set,
  S for SigmaField of X,
  F for sequence of S,
  f,g for PartFunc of X,REAL,
  A,B for Element of S,
  r,s for Real,
  a for Real,
  n for Nat;
reserve X for non empty set,
  S for SigmaField of X,
  f,g for PartFunc of X,REAL,
  A for Element of S,
  r for Real,
  p for Rational;

theorem Th26:
  f is A-measurable & g is A-measurable implies f+g is A-measurable
proof
  assume f is A-measurable & g is A-measurable;
  then R_EAL f is A-measurable & R_EAL g is A-measurable;
  then R_EAL f + R_EAL g is A-measurable by MESFUNC2:7;
  then R_EAL(f+g) is A-measurable by Th23;
  hence thesis;
end;
