Singularity confinement and chaos in two-dimensional discrete systems

We present a quasi-integrable two-dimensional lattice equation: i.e., a partial difference equation which satisfies a test for integrability, singularity confinement, although it has a chaotic aspect in the sense that the degrees of its iterates exhibit exponential growth. By systematic reduction to one-dimensional systems, it gives a hierarchy of ordinary difference equations with confined singularities, but with positive algebraic entropy including a generalized form of the Hietarinta–Viallet mapping. We believe that this is the first example of such quasi-integrable equations defined over a two-dimensional lattice. (letter)