Tuesday, February 18 from 2 to 3pm
Room: Mathematics 136
Speaker: Andrés Caicedo (BSU)
Title: An absoluteness result
Abstract: We present examples of some (Ramsey-theoretic) theorems of ZFC (whose standard proofs make blatant use of choice) that can be established in ZF as well. We provide a combinatorial proof of one of these statements, and also a general metamathematical argument (due to Asaf Karagila) showing they must be provable in ZF based simply on their logical complexity.