let r, s, p be ext-real number ; :: thesis: ( r <= s implies [.r,+infty .] \ ].p,s.[ = [.r,p.] \/ [.s,+infty .] )
p <= +infty by XXREAL_0:3;
hence ( r <= s implies [.r,+infty .] \ ].p,s.[ = [.r,p.] \/ [.s,+infty .] ) by Th300; :: thesis: verum