2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/79635We prove a decomposition theorem for the equivariant K-theory of actions of affine group schemes G of finite type over a field on regular separated noetherian algebraic spaces, under the hypothesis that the actions have finite geometric stabilizers and satisfy a rationality condition together with a technical condition which holds e.g. for G abelian or smooth. We describe in an Appendix various complicial bi-Waldhausen categories (in Thomason's terminology) modelling the equivariant K-theory of regular noetherian separated algebraic spaces.39 pages, no figures, ScientificWord 2.0. Final revised version accepted for publication in Duke Math. JAlgebraic GeometryK-Theory and Homology19E08; 14L30text