Lab Lunch: 23 April 2019 - John Longley

Title: Hercules and the Hydra

Abstract:

The marvellous battle between Hercules and the hydra was introduced by Kirby and Paris in 1982 to give an accessible example of an arithmetical statement that is true but not provable in Peano Arithmetic. I shall describe the original work, then show how some of the progeny of the original Kirby-Paris hydra have wormed their way into various areas of logic and computer science.