It has since been discovered that this theorem of Chen’s is false. We would like to thank Dechao Zheng for informing us of this fact, who in turn attributes his source to Carl Sundberg. Once one knows this, the fact that ‖g‖ is not equivalent to ‖g‖# can be directly shown. For example, if one tries the special case where the complex dimension n equals 2, one finds that ∫∫ |z1 − w1| |1− 〈z, w〉|5...

Let U be the unit polydisc of C n and φ = (φ1, . . . , φn) a holomorphic selfmap of U. By Bp(Un), B 0 (U) and B 0∗ (U) denote the p-Bloch space, Little p-Bloch space and Little star p-Bloch space in the unit polydisc U respectively, where p, q > 0. This paper gives the estimates of the essential norms of bounded composition operators Cφ induced by φ between Bp(Un) (B 0(Un) or B 0∗ (U) ) and Bq(...

Let U be the unit polydisc of C n and φ = (φ1, . . . , φn) a holomorphic self-map of U. By Bp(Un), B 0 (U) and B 0∗ (U) denote the p-Bloch space, Little p-Bloch space and Little star p-Bloch space in the unit polydisc U respectively, where p, q > 0. This paper gives the estimates of the essential norms of bounded composition operators Cφ induced by φ between Bp(Un) (B 0(Un) or B 0∗(Un) ) and Bq...

Let ϕ(z) = (ϕ 1 (z),...,ϕ n (z)) be a holomorphic self-map of D n and ψ(z) a holomorphic function on D n , where D n is the unit polydiscs of C n. Let 0 < α, β < 1, we compute the essential norm of a weighted composition operator ψC ϕ between α-Bloch space Ꮾ α (D n) and β-Bloch space Ꮾ β (D n).

We present a proof that in Orlicz spaces the Amemiya norm and the Orlicz norm coincide for any Orlicz function ‘p. This gives the answer for an open problem. We also give a description of the Amemiya type for the Mazur-Orlicz F-norm.

In this note, we provide detailed characterization of operators in terms norm-attainability and norm estimates Banach algebras. particular, establish the necessary sufficient conditions for derivations also give their bounds norm-attainable classes.