In differential geometry, a Nadirashvili surface is an immersed complete bounded minimal surface in R with negative curvature, Eugenio Calabi and Shing-Tung Yau had a question, about whether there was an immersed complete bounded minimal surface in R, Shing-Tung Yau is from Hong Kong and what type of American mathematician?
Nadirashvili surface:  This simultaneously answered a question of Hadamard about whether there was an immersed complete bounded surface in R with negative curvature, and a question of Eugenio Calabi and Shing-Tung Yau about whether there was an immersed complete bounded minimal surface in R. Shing-Tung Yau: Shing-Tung Yau ( ; ; born April 4, 1949) is a Hong Kong and naturalised American mathematician.
naturalised