which will be very useful for improving our work for the final version

The networks is most expressive if it only finds isomorphic graphs to be not different. We will add extensive captions to the figures to clarify. We indeed mean that global syms restrict to local syms and will clarify. R1 that for more general non-linear kernels, such a general statement does not hold. This is implied by Eq. (4), when the isomorphism is between different edges neighbourhoods.