2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/61346We prove an equivariant Grothendieck-Ogg-Shafarevich formula. This formula may be viewed as an étale analogue of well-known formulas for Zariski sheaves generalizing the classical Chevalley-Weil formula. We give a new approach to those formulas (first proved by Ellingsrud/Lønsted, Nakajima, Kani and Ksir) which can also be applied in the étale case.16 pages; v2: generalizations of a theorem of Ksir added and substantially revisedAlgebraic Geometry14F20; 14L30; 14H30text