
theorem Th26:
  for X being non empty set, Y being non empty Subset of ExtREAL,
F being Function of X,Y, x being Element of X holds inf F <= F.x & F.x <= sup F
proof
  let X be non empty set, Y be non empty Subset of ExtREAL, F be Function of X
  ,Y, x be Element of X;
  X = dom F by FUNCT_2:def 1;
  then F.x in rng F by FUNCT_1:def 3;
  hence thesis by XXREAL_2:3,4;
end;
