Homotopies and Maps between Eigenvalues of some Generalized Lucas Sequences and the Mandelbrot Set

Abstract

The eigenvalues of companion matrices associated with generalized Lucas sequences, denoted as L, exhibit a striking geometric resemblance to the Mandelbrot set M. This work investigates this connection by analyzing the statistical distribution of eigenvalues and constructing a variety of homotopies that map different regions of L to structurally corresponding subsets of M. In particular, we explore both global and piecewise homotopies, including a sinusoidal interpolation targeting the main cardioid and localized deformations aligned with the periodic bulbs. We also study a variation of the Jungreis map to better capture angular and radial structures. In addition to visual and geometric matching, we classify the eigenvalues according to their dynamical behavior, identifying subsets associated with hyperbolic, parabolic, Misurewicz, and Siegel disk points. Our findings suggest that meaningful correspondences between L and M must integrate both geometric deformation and dynamical classification. In light of these observations, we also suggest a conjectural homeomorphism between L and a dense subset of the Mandelbrot cardioid boundary, based on the behavior of the sinusoidal homotopy and the eigenvalue accumulation. Finally, we prove that the sinusoidal homotopy defines a homeomorphism (modulo countable exceptions) from L onto the boundary of the Mandelbrot cardioid, and, when composed with Douady's tuning map, extends to any baby cardioid or stable region of M, reinforcing the structural correspondence between these sets.