In this work, we investigate computational aspects of asynchronous cellular automata (ACAs), a modification of cellular automata in which cells update independently, following an asynchronous update schedule. We introduce flip automata networks (FANs), a simple modification of automata networks that remain robust under any asynchronous updating order. By using FANs as a middleman, we show that asynchronous automata can efficiently simulate their synchronous counterparts with a linear memory overhead, which improves upon the previously established quadratic bound. Additionally, we address the universality gap for (a)synchronous cellular automata-the boundary separating universal and non-universal automata, which is still not fully understood. We tighten this boundary by proving that all one-way asynchronous automata lack universal computational power. Conversely, we establish the existence of a universal asynchronous 6-state first-neighbor automaton in one dimension and a 3-state von Neumann automaton in two dimensions, which represent the smallest known universal constructions to date.
@InProceedings{baburin_et_al:LIPIcs.MFCS.2025.11, author = {Baburin, Ivan and Cook, Matthew and Gr\"{o}tschla, Florian and Plesner, Andreas and Wattenhofer, Roger}, title = {{Universality Frontier for Asynchronous Cellular Automata}}, booktitle = {50th International Symposium on Mathematical Foundations of Computer Science (MFCS 2025)}, pages = {11:1--11:18}, series = {Leibniz International Proceedings in Informatics (LIPIcs)}, ISBN = {978-3-95977-388-1}, ISSN = {1868-8969}, year = {2025}, volume = {345}, editor = {Gawrychowski, Pawe{\l} and Mazowiecki, Filip and Skrzypczak, Micha{\l}}, publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik}, address = {Dagstuhl, Germany}, URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.MFCS.2025.11}, URN = {urn:nbn:de:0030-drops-241182}, doi = {10.4230/LIPIcs.MFCS.2025.11}, annote = {Keywords: Universality, Asynchronous Cellular Automata, Automata Networks} }
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