Perspective on a challenge: Predicting the photochemistry of cyclobutanone. - Janoš, Jiří; List, Nanna Holmgaard; Orr-Ewing, Andrew J.; Suchan, Jiří; Barbatti, Mario; Bennett, Olivia; Brady, Marcus; Carmona-García, Javier; Crespo-Otero, Rachel; Eng, Julien; Fajen, O. Jonathan; Garavelli, Marco; et al. (Journal of Chemical Physics, 2026)