Elliptic soliton solutions, i.e., a hierarchy of functions based on an elliptic seed solution, are constructed using an elliptic Cauchy kernel, for integrable lattice equations of KadomtsevPetviashvili (KP) type. This comprises the lattice KP, modified KP (mKP) and Schwarzian KP (SKP) equations as well as Hirota's bilinear KP equation, and their successive continuum limits. The reduction to the elliptic soliton solutions of KdV type lattice equations is also discussed.
The lattice KP and Hirota equationsThe study of the discrete versions of soliton systems, i.e., systems given by integrable partial difference equations, have become in recent years a focus of attention in the theory of integrable systems. Among those systems, the discrete analogue of Kadomtsev-Petviashvili (KP) equations which define in three dimensional lattice, seem to form a universal class of systems. The first equation of this type was found by Hirota in [12] and was referred to as DAGTE (Discrete analogue of generalised Toda equation) which is the bilinear equationwhere the Hirota operators D i produce finite forward-and backward shifts, when acting on a pair of functions, in the corresponding lattice direction, i.e.,Special reductions of this equation, are obtained when the coefficients a 1 , a 2 , a 3 satisfy the condition a 1 + a 2 + a 3 = 0, but the full equation is integrable in the sense of multidimensional consistency for arbitrary parameters, see [5]. Miwa [18] reparametrized the equation in that restricted case, and hence in that form it is often referred to as Hirota-Miwa equation 1 . In this paper we will investigate a class of solutions of this and related three-dimensional lattice equations, comprising the following equations:1 Sometimes the full equation (representing the blinear discrete KP equation) is also (in our view erroneously) referred to as the Hirota-Miwa equation. In fact, in [18] only the restricted case was considered, and generalized to a four-term equation which is nowadays referred to as the Miwa equation.