Gittin 25: Retroactive Clarification
When a man wants to divorce a wife, and he has at least two, and he doesn't want to specify which one, and devises a plan for, let's say, whichever one comes to greet him first - the Gemara says, no. The get needs to be written in her name - they can't discover after the fact which wife was, lo and behold, the divorced one. But there many other circumstances where retroactive clarification does work.
The skinny
The skinny isn't ready yet — notes appear once the transcript is processed.