theorem
  A c= dom f & f is A-measurable & g is A-measurable implies max+(
  f+g) + max-f is A-measurable
proof
  assume that
A1: A c= dom f and
A2: f is A-measurable and
A3: g is A-measurable;
  f+g is A-measurable by A2,A3,Th26;
  then
A4: max+(f+g) is A-measurable by Th46;
  max-f is A-measurable by A1,A2,Th47;
  hence thesis by A4,Th26;
end;
