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Here, we argue that reservoir computing can be realized entirely within a coarse-grained, symbolic state space, and that constrained random walks on ordinal-pattern transition networks provide a natural instance of this realization, replacing the reservoir\u2019s continuous state space with a discrete and directly data-derived one. We develop a formal correspondence between the two frameworks, show that the echo-state property has a natural discrete analog in the ergodicity and spectral gap of the walk\u2019s underlying Markov chain, and illustrate the correspondence with a minimal example and an empirical one-step-ahead prediction task evaluated across five paradigmatic model systems. These systems exhibit dynamics that correspond to strictly periodic, quasiperiodic, chaotic, or stochastic signals. We argue that this symbolic reservoir perspective allows a redefinition of the reservoir substrate itself, replacing the requirement of a continuous, randomly generated dynamical system with any sufficiently ergodic, data-derived symbolic process. This opens a route toward interpretable, data-adaptive reservoirs whose internal structure is inferred rather than randomly assigned, with implications for surrogate-data methods and reservoir design more broadly.<\/jats:p>","DOI":"10.1063\/5.0355934","type":"journal-article","created":{"date-parts":[[2026,10,15]],"date-time":"2026-10-15T13:26:16Z","timestamp":1792070776000},"update-policy":"https:\/\/doi.org\/10.1063\/aip-crossmark-policy-page","source":"Crossref","is-referenced-by-count":0,"title":["Ordinal-pattern transition networks as a symbolic substrate for reservoir computing"],"prefix":"10.1063","volume":"36","author":[{"ORCID":"https:\/\/orcid.org\/0009-0007-4672-7431","authenticated-orcid":false,"given":"Max","family":"Potratzki","sequence":"first","affiliation":[{"name":"Department of Epileptology, University Hospital Bonn 1 , Bonn,","place":["Germany"]},{"name":"Helmholtz Institute for Radiation and Nuclear Physics, University of Bonn 2 , Bonn,","place":["Germany"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8295-6898","authenticated-orcid":false,"given":"Thomas G.","family":"de Jong","sequence":"additional","affiliation":[{"name":"Division of Business & Technology, Temple University, Japan Campus, 1-14-29 Taishido 3 , Setagaya-ku, Tokyo 154-0004,","place":["Japan"]},{"name":"School of Mathematical Sciences, Hebei Normal University 4 , 20 Nan\u2019erhuan East Road, Yuhua District, Shijiazhuang, Hebei 050024,","place":["China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5378-1582","authenticated-orcid":false,"given":"Michael","family":"Small","sequence":"additional","affiliation":[{"name":"Department of Mathematics and Statistics, The University of Western Australia 5 , Perth,","place":["Australia"]},{"name":"UWA Data Institute, The University of Western Australia 6 , Perth,","place":["Australia"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9274-1479","authenticated-orcid":false,"given":"Timo","family":"Br\u00f6hl","sequence":"additional","affiliation":[{"name":"Department of Epileptology, University Hospital Bonn 1 , Bonn,","place":["Germany"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"317","published-online":{"date-parts":[[2026,10,15]]},"reference":[{"key":"2026101509261050400_c1","doi-asserted-by":"publisher","first-page":"2056","DOI":"10.1038\/s41467-024-45187-1","volume":"15","year":"2024","journal-title":"Nat. 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