let p, r be ExtReal; :: thesis: ( r <= p implies ].r,+infty.[ \ {p} = ].r,p.[ \/ ].p,+infty.[ )
p <= +infty by XXREAL_0:3;
hence ( r <= p implies ].r,+infty.[ \ {p} = ].r,p.[ \/ ].p,+infty.[ ) by Th313; :: thesis: verum