Devin
index
Devin O’Keefe
Write-ups of things I’ve built or worked out, most with something you can run in the page.
github
Index
Mathematics
1 piece
The travelling salesman’s constant
Oct 2026
We prove an upper bound of 0.8618 for the travelling salesman’s constant, a result accepted into Terence Tao’s table of Optimisation Constants in Mathematics.
explainer · finished
Game-playing AI
3 pieces
Hnefatafl
Oct 2026
Using RL to train the world’s best AI for Hnefatafl, an ancient Viking board game, beating the previous world-best AI with 14 wins and 2 unfinished in 16 games
playable · finished
Jieqi
Oct 2026
An engine for Jieqi, Chinese chess played face down, beat the six other programs that could be run; its biggest gain came from valuing its own gambles better.
playable · finished
Solving Senet
Oct 2026
A program has solved a modern five-piece version of the ancient Egyptian race game senet. The side that throws first wins 50.25% with perfect play, and a small network plays almost as well.
playable · finished
Cryptography
3 pieces
The cardinal’s cipher
Oct 2026
In six lines of cipher that both editions left out, the cardinal governing Castile told Charles V in 1520 that the rebels had turned on the great nobles.
explainer · finished
An address and two key poems
Oct 2026
Number pairs printed unread among Iskra’s cipher letters give Lenin’s London address, and two printed poems are the keys to two other ciphers in the same letters.
explainer · finished
The ambassador’s cipher
Oct 2026
The decipherments bound with a French ambassador’s letters of 1558 give a key to his cipher, which reads part of the one letter left without a decipherment and finds the plain text of two more of his cipher passages in a book of 1895.
explainer · finished