Generalized Buzano Inequality

TAMARA BOTTAZZI; CRISTIAN CONDE

FILOMAT

UNIV NIS

Año: 2023 vol. 37

0354-5180

If P is an orthogonal projection defined on an inner product space H, then the inequality |⟨P x, y⟩| ≤ 1/2[∥x∥∥y∥ + |⟨x, y⟩|]fulfills for any x, y in H (see [10]). In particular, when P is the identity operator, then it recovers the famous Buzano inequality. We obtain generalizations of such classical inequality, which hold for certain families of bounded linear operators defined on H. In addition, several new inequalities involving the norm and numerical radius of an operator are established