Strict self-assembly of discrete self-similar fractals

Strict Self-Assembly of Discrete Self-Similar Fractals

Discrete self-similar fractals are infinite aperiodic shapes that have received much interest in the domain of tile self-assembly. For instance, in it was shown that the infinite Sierpinski triangle cannot strictly self-assemble in the aTAM, but a fibered approximation can be. In it was shown that additional DSSFs cannot strictly self-assemble in the aTAM, but their fibered approximations can. Just a few of the additional results related to DSSFs, including more impossibility results, other approximations, and strict self-assembly in other models can be found in .

While in it was conjectured that no DSSF can strictly self-assemble in the aTAM, that conjecture has been proven false. In fact, two different methods have been demonstrated for developing aTAM systems that strictly self-assemble DSSFs, and the following two sections give overviews of each.

DSSFs via Self-describing circuits

TODO: describe the work by Florent Becker in

DSSFs via Quines

TODO: describe the work by Hader and Patitz, in progress...

A quine is a computer program that, with no input, outputs a full copy of its own source code. In the context of the aTAM, a quine was defined, with respect to an intrinsically universal tile set \(U\), as a system \(\mathcal{Q} = (Q, \sigma, \tau)\) that begins from a single seed tile, (i.e. \(|\sigma| = 1)\) and grows into a terminal assembly, \(\alpha_\mathcal{Q}\), that is correctly formatted to be the seed assembly for a system \(\mathcal{S} = (U,\alpha_\mathcal{Q}, \tau)\) that uses \(U\) and its associated representation function \(R\) such that \(R\) maps \(\alpha_\mathcal{Q}\) to \(\sigma\) (i.e. \(R(\alpha_\mathcal{Q}) = \sigma)\) and \(\mathcal{S}\) intrinsically simulates \(\mathcal{Q}\).