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 Th312; :: thesis: verum