
doi: 10.1007/bf01156750
Let f(z) be regular or meromorphic in a domain D and let n(w), \(w=re^{it}\), be the number of roots of the equation \(f(z)=w\), which lie in D. Let us put \[ p(r)=(1/2\pi)\int^{2\pi}_{0}n(re^{it})dt,\quad W_{\mu}(R)=\int^{R}_{0}p(r)d(r^{2\mu}). \] If for some positive numbers p,\(\mu\) we have \(W_{\mu}(R)\leq pR^{2\mu}\) for all \(R>0\), then the function f(z) is called mean p-valent with respect to the \(\mu\)-area in D. We denote by \(\Sigma_{p,\mu}\) the class of all regular functions F(\(\zeta)\) which are mean p-valent with respect to the \(\mu\)-area in \(\{\) \(\zeta\) : \(| \zeta | >1\}\) and have the representation \[ F(\zeta)=\zeta^ p(1+\alpha_ 1\zeta^{-1}+\alpha_ 2\zeta^{- 2}+...) \] and by \(S_{p,\mu}\) the class of all regular functions f(z) which are mean p-valent with respect to the \(\mu\)-area in \(\{\) \(z: | z| 1\}. \] The following results are obtained: Theorem I. If \(F(\zeta)\in \Sigma'_{p,\mu}\) and \(c_ n(\lambda)\) are defined by the equality \[ (F(\zeta)/\zeta^ p)^{\lambda}=\sum^{\infty}_{n=0}c_ n(\lambda)\zeta^{-n},\quad c_ 0(\lambda)=1,\quad | \zeta | >1, \] then for \(\lambda\in (0,\mu]\) and not for all \(\lambda >\mu\) we have \[ \sum^{\infty}_{n=1}(n-p\lambda)| c_ n(\lambda)|^ 2\leq p\lambda. \] In addition \(| \alpha_ 1| \leq 2p\) for 2p\(\mu\geq 1\) and \(| \alpha_ 2| \leq p(2p-1)\) for \(p\mu\geq 1\). Theorem II. If \(f(z)\in S_{p,\mu}\), \(\lambda >0\) and \(c_ n(\lambda)\) are defined by the equality \[ (f(z)/z^ p)^{- \lambda}=\sum^{\infty}_{n=0}c_ n(\lambda)z^ n,\quad c_ 0(\lambda)=1,\quad | z| <1, \] then \[ \sum^{\infty}_{n=1}(n- p\lambda)| c_ n(\lambda)|^ 2\leq p\lambda. \] In addition \(| a_ 1| \leq 2p\).
General theory of conformal mappings, Special classes of univalent and multivalent functions of one complex variable (starlike, convex, bounded rotation, etc.), Coefficient problems for univalent and multivalent functions of one complex variable, mean p-valent, \(\mu\)-area
General theory of conformal mappings, Special classes of univalent and multivalent functions of one complex variable (starlike, convex, bounded rotation, etc.), Coefficient problems for univalent and multivalent functions of one complex variable, mean p-valent, \(\mu\)-area
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