2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/39052Some recent developments in the calculation of weak matrix elements on the lattice are reviewed. In particular, we concentrate on the application of MPSTV non-perturbative renormalization method to the operators relevant to kaon physics. The chiral behaviour of the $B_K$ parameter and the long-standing question of the $ΔI=1/2$ rule are discussed.8 pages, 1 figure. Talk presented at the NATO ASI on Masses of Fundamental Particles, Cargese August 1996, to appear in the proceedingsHigh Energy Physics - Latticetext