LFX

That's a known issue. But the last time I read about it no one had a clue what's the reason. I have the problem regularly, and just by luck, through deleting of the cache, it works after some tries.

You need to specify points. Like p6-7. The way I've done it the last time was grouping points, and then use the strreplace function to place the ‘-’ inbetween. Off the top of my head it goes like this:

p`strreplace(pointlist(), “ ”, “-”)

I recall someone made an operator for edge selection, but I couldn't find the topic.

Sry, but I don't get what are you after? The group you want to delete doesn't exist here, and you translate input B down, so there is no intersection with input A.