Tootfinder

Once upon a time someone who shall remain nameless (but whose initials are M.K.) added an error message to the Unix kernel's TTY driver (this was back in the early 1980's).
The message was intended to be purely internal and was generated whenever someone on a terminal hit Ctrl-C.
The message:
"Eat flaming death fascist pigs!"
Of course, being internal, it was never emitted to users, only to log files.
That is until we were demonstrating somethi…

All Substitution Is Local
Nidhish Shah, Shaurjya Mandal, Asfandyar Azhar
https://arxiv.org/abs/2604.01443 https://arxiv.org/pdf/2604.01443 https://arxiv.org/html/2604.01443
arXiv:2604.01443v1 Announce Type: new
Abstract: When does consulting one information source raise the value of another, and when does it diminish it? We study this question for Bayesian decision-makers facing finite actions. The interaction decomposes into two opposing forces: a complement force, measuring how one source moves beliefs to where the other becomes more useful, and a substitute force, measuring how much the current decision is resolved. Their balance obeys a localization principle: substitution requires an observation to cross a decision boundary, though crossing alone does not guarantee it. Whenever posteriors remain inside the current decision region, the substitute force vanishes, and sources are guaranteed to complement each other, even when one source cannot, on its own, change the decision. The results hold for arbitrarily correlated sources and are formalized in Lean 4. Substitution is confined to the thin boundaries where decisions change. Everywhere else, information cooperates. Code and proofs: https://github.com/nidhishs/all-substitution-is-local.
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