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Tame Twindragon


TameTwindragon

The tame twindragon is a planar self-similar fractal obtained from expansions using binary digits in the complex base beta=(1+isqrt(7))/2, a root of x^2-x+2=0 (Ngai et al. 2000). A normalization in the complex plane is the compact set

 T={sum_(k=1)^inftyd_kbeta^(-k):d_k in {0,1}}.

It satisfies the iterated function system

 T=beta^(-1)T union beta^(-1)(T+1).

Since |beta|=sqrt(2), the two pieces are congruent copies with scale factor 1/sqrt(2). They have disjoint interiors, making the tame twindragon a rep-tile of order 2. The figure shows a finite approximation with the two first-level pieces colored separately.

The tame twindragon has nonempty interior, equals the closure of its interior, and tiles the plane by translations (Bandt 1991, Ngai et al. 2000). Although it has the same two scale factors as the twindragon, the two fractals are not similar (Ngai et al. 2000).


See also

Fractal, Iterated Function System, Numeral System, Rep-Tile, Twindragon

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References

Bandt, C. "Self-Similar Sets 5. Integer Matrices and Fractal Tilings of R^n." Proc. Amer. Math. Soc. 112, 549-562, 1991. https://doi.org/10.1090/S0002-9939-1991-1036982-1.Ngai, S.-M.; Sirvent, V. F.; Veerman, J. J. P.; and Wang, Y. "On 2-Reptiles in the Plane." Geom. Dedicata 82, 325-344, 2000. https://doi.org/10.1023/A:1005206301454.

Cite this as:

Weisstein, Eric W. "Tame Twindragon." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/TameTwindragon.html

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