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 Th308; :: thesis: verum