On a question of Gary G. Gundersen concerning meromorphic functions sharing three distinct values IM and a fourth value CM

Xiao-Min Li, Qing-Fei Zhai, Hong-Xun Yi

In 1992, Gundersen (Complex Var. Elliptic Equ.20 (1992), no. 1-4, 99-106.) proposed the following famous open question: if two non-constant meromorphic functions share three values…