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

theorem
  for p being Real holds
  ].-infty,+infty.] \ {p} = ].-infty,p.[ \/ ].p,+infty.]
  by Th350,XXREAL_0:3;
