2002 seminar talk: Sharps, pistols, and the \Sigma^1_3 correctness of K
Talk held by Ralf Schindler (KGRC) at the KGRC seminar on 2002-01-17.
I'll give a simple proof of the following result of Steel and Welch: Let x be a solution to the \Pi^1_2 property \Phi(-), and suppose that x^#, x^##, x^###, etc. exist; suppose further that 0^pistol doesn't exist. Then K contains a solution to \Phi(-).