Differentially Transcendental Functions
  The aim of this paper is to exhibit a method for proving that certain analytic functions are not solutions of algebraic differential equations. The method is based on model-theoretic properties of differential fields and properties of certain known transcendental differential functions, as of $\Gamma(x)$. Furthermore, it also determines differential transcendency of solution of some functional equations. 
Zarko Mijajlovic, Branko Malesevic