let p, q be ext-real number ; :: thesis: ( p <= q implies ].-infty ,q.[ \ {p} = ].-infty ,p.[ \/ ].p,q.[ )
-infty <= p by XXREAL_0:5;
hence ( p <= q implies ].-infty ,q.[ \ {p} = ].-infty ,p.[ \/ ].p,q.[ ) by Th313; :: thesis: verum