2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/78108We compute the convolution product on the equivariant K-groups of the cyclic quiver variety. We get a q-analogue of double-loop algebras, closely related to the toroidal quantum groups previously studied by the authors. We also give a geometric interpretation of the cyclic quiver variety in terms of equivariant torsion-free sheaves on the projective plane.22 pages, AMS-texAlgebraic Geometrytext