Dessins d'Enfants, Their Deformations and Algebraic the Sixth Painlev\'e and Gauss Hypergeometric Functions

We consider an application of Grothendieck's dessins d'enfants to the theory of the sixth Painlev\'e and Gauss hypergeometric functions: two classical special functions of the isomonodromy type. It is shown that, higher order transformations and the Schwarz table for the Gauss hypergeometric function are closely related with some particular Belyi functions. Moreover, we introduce a notion of deformation of the dessins d'enfants and show that one dimensional deformations are a useful tool for construction of algebraic the sixth Painlev\'e functions.