The $\mathrm{\Delta }I=1\mathrm{/}2$ rule and other matrix elements

Recent work by J.Prades and myself on $K\to \pi \pi$ is described. The method we use to consistently connect long and short distances is described and numerical results for the $\mathrm{\Delta }I=1\mathrm{/}2$ rule and on $B_6$, the parameter relevant for the strong part of ${ϵ}^{\mathrm{\prime }}\mathrm{/}ϵ$, are given in the chiral limit.