I don't know the names as they are used here, but my gym uses a ton of deep half and has a very unique 1/2guard game. bear in mind, we are mostly in gi, but the move I am thinking of works for both. It is probably the highest percentage sweep I know, even when the person knows what you are going for - you really have to alter your top game significantly to defend it, which sets up a lot of other stuff. My teacher calls it "little chair" You go deep, and then pendulum your legs back and forth to get them off balance and work their trapped leg (the one trapped by your lower body) closer to your free arm. When you can, dig your free arm under that leg near the ankle, palm up, and then rock your legs back towards them like you are going back into regular half guard. It completely opens their base up and they flop backwards. Because of your grips, if you stay tight, you have a REALLY easy pass by just scorpioning your leg. If this doesnt make sense, let me know. I'm trying to see if my friend has a video camera I can borrow, unless any of you do and live n the Bay Area...