Key points are not available for this paper at this time.
It is shown that if A is a bounded linear operator on a complex Hilbert space, then w (A) 12 (\| A \| + \| A² \|^1/2), where w (A) and \|A\| are the numerical radius and the usual operator norm of A, respectively. An applicati
Fuad Kıttaneh (2003) studied this question.