11. His research interests involve the intersection of complex variables , differential geometry, and algebraic geometry. 12. Generalized Cauchy Riemann System in Many Independent Complex Variables . 13. Multivalued functions of a complex variable have branch points. 14. Alternatively, each point in a graph may depict the value of a single complex variable . 15. When considered defined by a complex variable , the hyperbolic functions are rational functions of holomorphic. 16. At Princeton, Hua worked on matrix theory, functions of several complex variables , and group theory. 17. Several complex variables is the study of such holomorphic functions in " n " variables. 18. His early work pertained to the theory of functions of a complex variable , particularly, complex dynamics. 19. He also published the second Carus Mathematical Monograph, " Analytic Functions of a Complex Variable ." 20. These concepts are more important in the case " n " > 1 of several complex variables .