ISSN 1855-3966 (printed edn.), ISSN 1855-3974 (electronic edn.) ARS MATHEMATICA CONTEMPORANEA 23 (2023) #P2.01 https://doi.org/10.26493/1855-3974.2712.6be (Also available at http://amc-journal.eu) The edge-transitive polytopes that are not vertex-transitive* Frank Göring Faculty of Mathematics, University of Technology, 09107 Chemnitz, Germany Martin Winter † Mathematics Institute, University of Warwick, Coventry CV4 7AL, United Kingdom Received 27 October 2021, accepted 19 March 2022, published online 28 October 2022 Abstract In 3-dimensional Euclidean space there exist two exceptional polyhedra, the rhombic dodecahedron and the rhombic triacontahedron, the only known polytopes (besides poly- gons) that are edge-transitive without being vertex-transitive. We show that these poly- hedra do not have higher-dimensional analogues, that is, that in dimension d ≥ 4, edge- transitivity of convex polytopes implies vertex-transitivity. More generally, we give a classification of all convex polytopes which at the same time have all edges of the same length, an edge in-sphere and a bipartite edge-graph. We show that any such polytope in dimension d ≥ 4 is vertex-transitive. Keywords: Convex polytopes, symmetry of polytopes, vertex-transitive, edge-transitive. Math. Subj. Class. (2020): 52B15, 52B11 *This article appears as Chapter 6 in the second author’s doctoral thesis from 2021. The authors thank the anonymous referees for their careful reading and their many remarks that led to an improvement of the arti- cle in several ways. †Corresponding author. E-mail addresses: frank.goering@mathematik.tu-chemnitz.de (Frank Göring), martin.h.winter@warwick.ac.uk (Martin Winter) cb This work is licensed under https://creativecommons.org/licenses/by/4.0/ ISSN 1855-3966 (tiskana izd.), ISSN 1855-3974 (elektronska izd.) ARS MATHEMATICA CONTEMPORANEA 23 (2023) #P2.01 https://doi.org/10.26493/1855-3974.2712.6be (Dostopno tudi na http://amc-journal.eu) Povezavno tranzitivni politopi, ki niso točkovno tranzitivni* Frank Göring Faculty of Mathematics, University of Technology, 09107 Chemnitz, Germany Martin Winter † Mathematics Institute, University of Warwick, Coventry CV4 7AL, United Kingdom Prejeto 27. oktobra 2021, sprejeto 19. marca 2022, objavljeno na spletu 28. oktobra 2022 Povzetek V 3-dimenzionalnem evklidskem prostoru obstajata dva izjemna poliedra, rombski do- dekaeder in rombski triakontaeder, edina znana politopa (poleg poligonov), ki sta pove- zavno tranzitvna, ne pa tudi točkovno tranzitivna. Pokažemo, da za ta dva poliedra ne obstajajo nobene podobne strukture v višjih dimenzijah, to pomeni, da v dimenziji d ≥ 4 povezavna tranzitivnost konveksnega politopa implicira točkovno tranzitivnost. Splošneje, podamo klasifikacijo vseh konveksnih politopov, ki imajo hkrati vse povezave iste dolžine, včrtano sfero, ki se vsake povezave dotika v eni sami točki, ter dvodelen povezavni graf. Pokažemo, da je vsak tak politop v dimenziji d ≥ 4 točkovno tranzitiven. Ključne besede: Konveksni politopi, simetrija politopov, točkovno tranzitiven, povezavno tranzitiven. Math. Subj. Class. (2020): 52B15, 52B11 *Ta članek predstavlja 6. poglavje doktorske disertacije drugega avtorja iz leta 2021. Avtorja se zahvaljujeta neznanim recenzentom za skrbno branje in številne pripombe, ki so vodile k marsikaterim izboljšavam. †Kontaktni avtor. E-poštna naslova: frank.goering@mathematik.tu-chemnitz.de (Frank Göring), martin.h.winter@warwick.ac.uk (Martin Winter) cb To delo je objavljeno pod licenco https://creativecommons.org/licenses/by/4.0/