Kaleidoscopic Symmetries and Self-Similarity of Integral Apollonian Gaskets

Abstract

We describe various kaleidoscopic and self-similar aspects of the integral Apollonian gaskets - fractals consisting of close packing of circles with integer curvatures. Self-similar recursive structure of the whole gasket is shown to be encoded in transformations that forms the modular group $SL(2,Z)$. The asymptotic scalings of curvatures of the circles are given by a special set of quadratic irrationals with continued fraction $[n+1:\overline{1,n}]$ - that is a set of irrationals with period-2 continued fraction consisting of $1$ and another integer $n$. Belonging to the class $n=2$, there exists a nested set of self-similar kaleidoscopic patterns that exhibit three-fold symmetry. Furthermore, the even $n$ hierarchy is found to mimic the recursive structure of the tree that generates all Pythagorean triplets

References in corpus (2)

• A Tale of Two Fractals: The Hofstadter Butterfly and The Integral Apollonian Gaskets
• On a Diophantine equation that generates all integral Apollonian Gaskets