let p, s be ExtReal; :: thesis: ( p <= s implies [.p,+infty.] \ ].p,s.[ = {p} \/ [.s,+infty.] )
p <= +infty by XXREAL_0:3;
hence ( p <= s implies [.p,+infty.] \ ].p,s.[ = {p} \/ [.s,+infty.] ) by Th322; :: thesis: verum