“…This concept [Fliess et al(1995)], [Fliess et al(1999)] (see also the books [Sira-Ramírez & Agrawal(2004)], [Lévine(2009)], [Rigatos(2015)], [Rudolph(2021)]) has given rise, as is commonly known, to numerous concrete applications mainly in engineering (see, e.g., [Bonnabel & Clayes(2020)] for a recent excellent 1 CRAN (CNRS, UMR 7039)), Université de Lorraine, BP 239, 54506 Vandoeuvre-lès-Nancy, France; cedric.join@univ-lorraine.f 2 Dipartimento di Matematica e Geoscienze, Università di Trieste, Via Alfonso Valerio 12, 34127 Trieste, Italy; alberto.d'onofrio@units.it 3 LIX (CNRS, UMR 7161), École polytechnique, 91128 Palaiseau, France; Michel.Fliess@polytechnique.edu 4 AL.I.E.N., 7 rue Maurice Barrès, 54330 Vézelise, France; {cedric.join, michel.fliess,}@alien-sas.com publication about cranes), but also in other domains (see, e.g., [Guéry-Odelin et al(2019)] in quantum physics). Also of particular interest here is its use [Hametner et al(2022)] for COVID-19 predictions. Take a flat system with a single control variable u(t) and a flat output variable y(t).…”