Three Bayesian concepts in the context of the breaking of the naval Enigma code during World War II

Maíra Bittencourt

IFCH – Unicamp

**Abstract.** Jack Good (1916-2009) was a Bayesian statistician who worked with Alan Turing (1912-1954) as his assistant at Bletchley Park during the World War II, from 1941 to 1943. They worked as cryptanalysts at the Government Code and Cypher School (GC&CS) with about eight more people, trying to break the naval enigma code used by the German navy. They were able to break the code by a process Turing called *Banburismus*. Good (2000, p. 101) refers to this method as a “sequential Bayesian procedure”. The main goal of this seminar is to explain three Bayesian concepts related to this procedure: the Bayes factor, weight of evidence and information update.

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