Pointwise lower bounds in growth spaces with little $o$ conditions
DOI:
https://doi.org/10.7146/math.scand.a-158077Abstract
Pointwise lower bounds on the open unit disc $\mathbb{D} $ for the sum of the moduli of two analytic functions $f$ and $g$ (or their derivatives) are known in several cases, like $f,g$ belonging to the Bloch space $\mathcal{B} $, BMOA or the weighted Hardy space $H_\omega ^\infty $. We modify the proofs of two important cases, proved by Ramey-Ullrich and Abakumov-Doubtsov, for functions with little $o$ growth conditions.
References
Abakumov, E., and Doubtsov, E., Moduli of holomorphic functions and logarithmically convex radial weights, Bull. Lond. Math. Soc. 47 (2015), no. 3, 519–532. https://doi.org/10.1112/blms/bdv026
Blasco, O., Lindström, M., and Taskinen, J., Bloch-to-BMOA compositions in several complex variables, Complex Var. Theory Appl. 50 (2005), no. 14, 1061–1080. https://doi.org/10.1080/02781070500277672
Choe, B. R., and Rim, K. S., Fractional derivatives of Bloch functions, growth rate, and interpolation, Acta Math. Hungar. 72 (1996), no. 1–2, 67–86. https://doi.org/10.1007/BF00053698
Girela, D., Analytic functions of bounded mean oscillation, Complex function spaces (Mekrijärvi, 1999), 61–170, Univ. Joensuu Dept. Math. Rep. Ser., 4, Univ. Joensuu, Joensuu, 2001.
Lou, Z., Composition operators on Bloch type spaces, Analysis (Munich) 23 (2003), no. 1, 81–95. https://doi.org/10.1524/anly.2003.23.1.81
Pommerenke, Ch., Boundary behaviour of conformal maps, Grundlehren der mathematischen Wissenschaften, 299. Springer-Verlag, Berlin, 1992. https://doi.org/10.1007/978-3-662-02770-7
Ramey, W., and Ullrich, D., Bounded mean oscillation of Bloch pull-backs, Math. Ann. 291 (1991), no. 4, 591–606. https://doi.org/10.1007/BF0144522
Wulan, H., and Zhu, K., Bloch and BMO functions in the unit ball, Complex Var. Elliptic Equ. 53 (2008), no. 11, 1009–1019. https://doi.org/10.1080/17476930802429123
Zhu, K., Operator theory in function spaces, second edition. Mathematical Surveys and Monographs, 138. American Mathematical Society, Providence, RI, 2007. https://doi.org/10.1090/surv/138