The Henon map was proposed in 1976 by the French mathematician Michel Hénon. It is a simplified model of the Poincaré map for the Lorenz model consisting in transforming continuous equations into a discrete iterated system :

                        x(n+1) = 1 - a.x(n)² + y(n)
                        y(n+1) = b.x(n)

a controls non-linearity
b is the rate of area contraction