On singular direction of meromorphic function and its derivatives (Q2372839)

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On singular direction of meromorphic function and its derivatives
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    On singular direction of meromorphic function and its derivatives (English)
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    2 August 2007
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    In the paper the author deals with the singular direction of a meromorphic function \(f\). Let us denote by \(n(r, \theta, \varepsilon, f; a)\) the number of \(a\)-points of \(f\) in \(\{z : \mid \arg z - \theta \mid < \varepsilon \} \cap \{z : \mid z \mid < r\}\), counted with multiplicities. Following result is proved in the paper: Suppose that \(f\) is a meromorphic function defined on the whole complex plane and satisfies the growth condition \(\displaystyle \limsup\limits_{r \to \infty}\frac{T(r, f)}{(\log r)^{\lambda}} = \infty\) for \(\lambda \geq 2\). Then there exists a ray \(\arg z = \theta_{0}\) such that for any \(\varepsilon ( > 0 )\) and positive integer \(k\), and any complex numbers \(a, b (\neq 0)\) , we have \[ \limsup\limits_{r \to \infty}\frac{n(r, \theta_{0}, \varepsilon , f; \infty) + n(r, \theta_{0}, \varepsilon , f; a) + n(r, \theta_{0}, \varepsilon , f^{(k)}; b) }{(\log r)^{\lambda - 1}} = \infty. \]
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    Singular direction
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    Meromorphic function
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    Derivative
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