Self-Assembly of Tiles: Theoretical Models, the Power of Signals, and Local Computing
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Western University Scholarship@Western Electronic Thesis and Dissertation Repository 12-1-2017 11:00 AM Self-Assembly of Tiles: Theoretical Models, the Power of Signals, and Local Computing Amirhossein Simjour The University of Western Ontario Supervisor Prof. Lila Kari The University of Western Ontario Graduate Program in Computer Science A thesis submitted in partial fulfillment of the equirr ements for the degree in Doctor of Philosophy © Amirhossein Simjour 2017 Follow this and additional works at: https://ir.lib.uwo.ca/etd Part of the Other Computer Sciences Commons, and the Theory and Algorithms Commons Recommended Citation Simjour, Amirhossein, "Self-Assembly of Tiles: Theoretical Models, the Power of Signals, and Local Computing" (2017). Electronic Thesis and Dissertation Repository. 5137. https://ir.lib.uwo.ca/etd/5137 This Dissertation/Thesis is brought to you for free and open access by Scholarship@Western. It has been accepted for inclusion in Electronic Thesis and Dissertation Repository by an authorized administrator of Scholarship@Western. For more information, please contact [email protected]. Abstract DNA-based self-assembly is an autonomous process whereby a disordered system of DNA sequences forms an organized structure or pattern as a consequence of Watson-Crick comple- mentarity of DNA sequences, without external direction. In this research we study the theoretical power of different mathematical models of self- assembly systems. The presented models are proposed to reduce the gap between self-assembly models and models that have been used in existing theoretical researches such as language theory and robotics. We propose self-assembly (SA) hypergraph automata as an automata- theoretic model for patterned self-assembly. We investigate the computational power of SA- hypergraph automata and show that for every recognizable picture language, there exists an SA- hypergraph automaton that accepts this language. Conversely, we prove that for any restricted SA-hypergraph automaton, there exists a Wang Tile System, a model for recognizable picture languages, that accepts the same language. We also study complex self-assembly models and investigate the computational power of some variants of the Signal-passing Tile Assembly Model (STAM), as well as propose the concept of Smart Tiles, i.e., tiles with glues that can be activated or deactivated by signals, and which possess a limited amount of local computing capability. We demonstrate the potential of smart tiles to perform some robotic tasks such as replicating complex shapes. Keywords: DNA based self-assembly, self-assembly of tiles, hypergraph automata, smart tiles i Co-Authorship Statement This thesis consists of three research articles that are published or are submitted. For all the articles, the authors names are listed alphabetically. The contribution of each of the co-authors are listed below. The article in chapter three ”Hypergraph Automata: a Theoretical Model for Patterned Self- assembly.” by Lila Kari, Steffen Kopecki, Amirhossein Simjour is published in International Journal of Foundations of Computer Science 25(4): 419-440 (2014). LK- research idea, co-writing proofs of theorems; SK- co-writing proofs of theorems, rewriting of the theorem 3.4.1, manuscript writing and editing; AS- research idea, first manuscript draft, proof of the theorems. The article in chapter four ”Simplifying the Role of Signals in Tile Self-assembly.” by Lila Kari, Amirhossein Simjour is submitted and is under review. LK- research idea, co-writing proofs of theorems, manuscript writing and editing; AS- research idea, first manuscript draft, proof of the theorems. The article in chapter five ”Smart Tile Self-Assembly and Replication.” by Lila Kari, Amirhossein Simjour is published in Fundamenta Informaticae 154(1-4): 239-260 (2017) . LK- research idea (specifically started the idea of definition of tiles with computational power), co-writing proofs of theorems, manuscript writing and editing; AS- research idea, first manuscript draft, proof of the theorem. ii Acknowledgements I am glad to acknowledge all of those who played a role to complete this thesis, whether large or small. I would like to take this opportunity to express how truly grateful I am to my supervisor, Dr. Lila Kari for her continuous commitment and support she has shown me throughout my study. To my sister, Narges who supported me in Canada and played the role of my entire family, thank you. I would like to thank my parents for all the support from thousands of miles away. Thank you for being there exactly when I needed you. Last but not the least, thanks to my wife Mahboubeh who have given me spirit and support in completing my thesis. THANK YOU! iii Contents Abstract i Co-Authorship Statement ii Acknowlegements iii List of Figures vii List of Tables x List of Appendices xi 1 Introduction 1 1.1 Hypergraph Automata: A Theoretical Model for Patterned Self-assembly . 2 1.2 The Computational Power of Glue-deactivating Signals in Tile Self-assembly . 3 1.3 Smart Tiles and Replication . 3 2 Literature review 5 2.1 Preliminaries . 6 2.1.1 Mathematical Description . 8 2.1.2 Computational Power . 12 2.2 Error in Self-assembly . 15 2.3 DNA-based Nanorobotics . 18 2.4 2D Grammars . 21 Bibliography 25 iv 3 Hypergraph Automata: A Theoretical Model for Patterned Self-assembly 33 3.1 Introduction . 33 3.2 Preliminaries . 35 3.3 Hypergraph Automata . 38 3.4 Hypergraph Automata for Picture Languages . 45 3.5 Conclusion . 56 Bibliography 57 4 Simplifying the Role of Signals in Tile Self-assembly 60 4.1 Introduction . 60 4.2 The Detachable Tile Assembly Model . 62 4.2.1 Formal Definition of DTAM . 64 4.2.2 Transitions . 66 4.3 Turing Universality . 72 4.4 Self-assembly of Thin Rectangles . 79 4.4.1 Informal description of the DTAM tile assembly system . 79 4.4.2 Detailed description of the DTAM tile assembly system . 82 4.4.3 DTAM tile complexity and waste analysis . 95 4.5 Conclusions . 96 Bibliography 96 4.6 Addendum . 99 5 Smart Tile Self-Assembly and Replication 101 5.1 Introduction . 101 5.2 Smart Tile Assembly . 103 5.2.1 Basic Definitions . 103 5.2.2 The Smart Tile Assembly Model . 106 5.3 A Smart Tile Assembly System that Replicates L-Convex Shapes . 113 5.4 Discussion and Future Work . 126 v Bibliography 127 6 Conclusion 130 A Appendix: Examples of SA-Hypergraph Automata 132 Curriculum Vitae 137 vi List of Figures 2.1 DAO and DAE tiles . 8 2.2 An example of a tile assembly system with a seed . 11 2.3 An example of flipped tiles . 17 3.1 An example of Wang tile system . 37 3.2 The self-assembly of a single coloured pattern . 38 3.3 Transition in hypergraph automata . 41 3.4 Underlying graph of the SA-hypergraph automaton that constructs a coloured pattern . 42 3.5 Step by step construction of a picture graph . 44 3.6 Hyperedges of a hypergraph automaton A that recognizes a recognizable pic- ture language L .................................. 47 3.7 Want tile system that accepts the same language as an SA-hypergraph automaton 51 4.1 A detachable tile in the DTAM . 64 4.2 An example of a general configuration and the assembly-graph associated to it . 68 4.3 An example of an attachment transition . 70 4.4 Simulation of a Turing machine using a deterministic zig-zag tile assembly system at temperature 2 . 74 4.5 The original tiles from the deterministic zig-zag tile assembly model at temper- ature 2, and their corresponding gadgets made out of SDTAM tiles . 75 4.6 The tiles that are used in the bit reader part of the gadgets . 76 4.7 The idea of the steps that replace an M × (M! + 2C) rectangle by an (M + 1) × ((M + 1)! + 2C) rectangle . 80 4.8 The use of the mirror rectangle in preventing unexpected attachments . 81 vii 4.9 The attachment of two rectangles and start of the column replacement . 83 4.10 A thin rectangle that is the input of Step 1 of the construction, and the glues on the tiles of its bottom edge . 84 4.11 The tile types that are used in the construction of a thin rectangle and their respective glues . 85 4.12 A detailed view of Step 2, and the attachment of the first column in Step 3 of the construction of a thin rectangle . 87 4.13 Step 3 (expansion), and Step 4 (reattachment) of the construction of a thin rectangle. Part 1 . 88 4.14 Step 3 (expansion), and Step 4 (reattachment) of the construction of a thin rectangle. Part 2 . 89 4.15 The tiles that are involved in the attachment of the left and right parts of the rectangles . 95 5.1 An example of an attachment transition . 108 5.2 A smart-TAM system at temperature 1 with a single tile type that can assemble a final configuration consisting of a row of three tiles . 112 5.3 An example of an L-convex supertile . 114 5.4 An example of an L-convex supertile with the border glues needed for its repli- cation by the smart-TAM system . 116 5.5 The general idea of the replication process of an L-convex supertile of a given shape, by a smart tile self-assembly system . 117 5.6 The bijective mapping between the glues on the border of the original supertile and the glues on the border of the quarter-rectangle . 117 5.7 The result of Step 1: Filling all four quarter-rectangles around the original supertile . 118 5.8 The rectangular hole that is obtained at the end of Step 2 . 119 5.9 The tile set Θborder-ne = fT1;:::; T6g, and Θreplica = fTreplicag .