Skelet #17 and the fifth Busy Beaver number

Authors :: Xu, Chris
Publication Year :: 2024
Abstract: We prove nonhalting of the Turing machine dubbed "Skelet #17", known to be one of the toughest 5-state, 2-symbol Turing machines to analyze. Combined with the efforts of The Busy Beaver Challenge, we are therefore able to show that BB(5), the fifth Busy Beaver number, equals 47,176,870.<br />Comment: added more references, fixed a broken link, and streamlined Proposition 3.4