theorem :: BORSUK_5:91
  for b being Real holds ].-infty,b.] /\ ].p,+infty.[ = ].p,b.]
proof
  let b be Real;
A1: b in REAL by XREAL_0:def 1;
  -infty <= p by XXREAL_0:5;
  hence thesis by A1,Th159,XXREAL_0:9;
end;
