let s be ext-real number ; :: thesis: for p being real number holds [.-infty,+infty.[ \ ].p,s.[ = [.-infty,p.] \/ [.s,+infty.[
let p be real number ; :: thesis: [.-infty,+infty.[ \ ].p,s.[ = [.-infty,p.] \/ [.s,+infty.[
p in REAL by XREAL_0:def 1;
hence [.-infty,+infty.[ \ ].p,s.[ = [.-infty,p.] \/ [.s,+infty.[ by Th325, XXREAL_0:9; :: thesis: verum