Anthropic's Claude Fable 5.1 appears to have cracked a centuries-old number puzzle that researchers considered unsolved. The 'Cyphral Distich' by Sir Thomas Urquhart, published in 1653, consists of two lines of 32 numbers each. It is the company's first major cryptanalysis breakthrough since its initial release in 2023.
Vals AI reported that Fable 5.1 solved the puzzle in 44 minutes with no human help. That compares with months of effort by other frontier models, which none produced a verifiable solution. The key was hiding in the book itself.
Each number points to a word in one of the 32 sections of Urquhart's publication.
"The solution is simple, and humans could have solved it too," said Vals AI. "Fable 5.1 succeeded not through better cryptanalysis but through systematic trial and error and sheer persistence." The announcement follows a series of AI breakthroughs in historical codebreaking.
The source did not say how the model identified the puzzle, and it remains unclear if other similar puzzles exist. The company did not comment on potential applications for historical research or cryptography.
Source: thedecoder
