reserve x for set,
  p,q,r,s,t,u for ExtReal,
  g for Real,
  a for Element of ExtREAL;

theorem :: MEASURE6:37
  ].+infty,p.] = {}
proof
  not ex x being object st x in ].+infty,p.]
  proof
    given x being object such that
A1: x in ].+infty,p.];
    reconsider s = x as ExtReal by A1;
    +infty < s by A1,Th2;
    hence contradiction by XXREAL_0:3;
  end;
  hence thesis;
end;
