We're studying the reactions of alkenes with halogens, and while I understand the mechanism, I don't see why a bromonium ion would be more stable than a carbocation. Doesn't it have an increase in energy from ring strain?
Also, for something to undergo anti addition, does it have to add from opposite sides *every* time? Because the mechanism reminded me of the addition of HX to alkynes, where they say that you usually have a trans product, but that there are exceptions. Would this reaction count as anti addition, or do the exceptions make this not count as anti?