THIS DIFFICULT PAPER is a sampling of the extraordinary thinking that physicists studying complexity and black holes are engaged in, and how purely mathematical and logical operations are being used to dissect the possibilities within such an inscrutable object. An exceptionally interesting and challenging paper.
https://onlinelibrary.wiley.com/doi/full/10.1002/prop.201500092?casa_token=8OO3b1OY4e4AAAAA%3ARqriAgTwtxnvsxl09CqnNy79m7l4ye7ZrkZxcLtObB9kHsTwYgzBuIV2X-xXQ7ezoR6VQPfQLCS-vnI