Didn't really enjoy this one. Only solved one group, before running out of time, and couldn't get the link term. I got another link after the wall resolved, and was kicking myself for missing the group itself, but to be honest I didn't really understand the explanations two of the other three groups, including the one I'd sorted out. If I do vaguely understand those groupings, I don't really think they should be in the same grid, as there's a distinct overlap.