let r be ExtReal; :: thesis: for s being Real holds ].r,+infty.[ \ [.s,+infty.[ = ].r,s.[
let s be Real; :: thesis: ].r,+infty.[ \ [.s,+infty.[ = ].r,s.[
s in REAL by XREAL_0:def 1;
hence ].r,+infty.[ \ [.s,+infty.[ = ].r,s.[ by Th195, XXREAL_0:9; :: thesis: verum