Symmetry Restrictions onK→2πAmplitudes

The restrictions on the $K\to 2\pi$ amplitudes which follow from the general $\mathrm{SU}\left(3\right)\mathrm{}$ and chiral $\mathrm{SU}\left(3\right)\mathrm{}\otimes \mathrm{SU}\left(3\right)\mathrm{}$ effective weak interactions are investigated. In particular it is found that the peculiar zero-energy limits obtained in the "current-algebra" approach are a consequence of $\mathrm{SU}\left(3\right)\mathrm{}$ invariance for the current-current weak Hamiltonian wherein the symmetry breaking is thought to result from continuation of the external meson masses to their physical values.