2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/59302We prove a conjecture of Nakajima (for type A the result was announced by Ginzburg- Vasserot) giving a geometric realization, via quiver varieties, of the Yangian of type ADE (and more in general of the Yangian associated to every symmetric Kac-Moody Lie algebra). As a corollary we get that tthe characters of the simple finite dimensional representations of the quantized affine algebra and that of the yangian coincide.9 pages, AMS-tex, final version accepted for publication in Letters in Math. PhysQuantum Algebratext