In scorelore and reckoninglore, Bayes' Rede is a rede for either knowing some haps' oftenness together, or for frothering belief after haps.
The mean form of Bayes' rede works if haps A and B are not the same, and B happens oftener than naught.
As with many scorelored redes, Bayes' rede tells of two worths that are the same.
- The worth of the oftenness of A times the oftenness B given A is the same as the worth of the oftenness of B times the oftenness of A given B.
- The oftenness of hap A is the same as the worth of the oftenness of A given B times the oftenness of B split by the oftenness of B given A
In unknownworthings reckoning,
p(A|B) * p(B) = p(B|A)*p(A)
The rede is named for Thomas Bayes, a trustman and scoreloreman, though folk believe in it thanks to a Frenchman named Pierre-Simon Laplace.