A GENERALIZATION OF LIOUVILLE′S THEOREM ON INTEGRATION IN FINITE TERMS
Utsanee Leerawat, Vichian Laohakosol · Journal of the Korean Mathematical Society · 2002
A generalization of Liouville's theorem on integration in finite terms, by enlarging the class of fields to an extension called Ei-Gamma extension is established. This extension includes the $\varepsilon$ L-elementary extension of Singer, Saunders and Caviness and contains the Gamma function.