Academic-turned-teacher (but still doing research as a hobby), interested in mathematical logic - specifically, computability theory and reverse mathematics, set theory, and abstract model theory. I'm also interested in other Nifty Things, in mathematics and elsewhere.

Since the SE system only allows temporary bounties, I am here informally "perma-bountying" the following ten questions, each for 1000 points:

**Geometry and topology**:**Model theory**:**Descriptive set theory**:**Set theory**:**Computability theory**: