Complete the proof of Theorem 7.1.5 by showing that
||Tyf - f||1 → 0 as y → 0
for all f € L'(R).
Theorem 7.1.5 (Riemann-Lebesgue's lemma) For f € L'(R), ƒ is a continuous function which tends to zero as y -> [infinity]; that is, f € Co (R).