Teurema da Lehto

Al síes $v\in ℂ$, $𝒲$ un intuurn da $v$; la síes $g$ una funziun merumorfa sü $𝒲\setminus \{v\}$, igaant una singülaritaa essenziala a $v$ e $g^{\mathrm{♯}}$ la derivada sférica de $g$. Alura $\underset{z\to v}{\mathrm{lim\; sup}}|z-v|\cdot g^{\mathrm{♯}}(z)\ge 1/2$.

Refereenz

Olli Lehto, The spherical derivative of meromorphic functions in the neighbourhood of an isolated singularity, Commentarii Mathematici Helvetici, vol 33 p.196-205