Riccati Solutions of Discrete Painlev\'e Equations with Weyl Group Symmetry of Type $E_8^{(1)}$

Abstract

We present a special solutions of the discrete Painlev\'e equations associated with $A_0^{(1)}$, $A_0^{(1)*}$ and $A_0^{(1)**}$-surface. These solutions can be expressed by solutions of linear difference equations. Here the $A_0^{(1)}$-surface discrete Painlev\'e equation is the most generic difference equation, as all discrete Painlev\'e equations can be obtained by its degeneration limit. These special solutions exist when the parameters of the discrete Painlev\'e equation satisfy a particular constraint. We consider that these special functions belong to the hypergeometric family although they seems to go beyond the known discrete and $q$-discrete hypergeometric functions. We also discuss the degeneration scheme of these solutions.