 Independently, unaware of Bayes work, Pierre-Simon Laplace developed Bayes' theorem in 1774.Bayesian inference was widely used until 1900s when there was a shift to frequentist inference, mainly due to computational limitations.Based on Bayes' theorem, the bayesian approach combines the prior probability of a tree P(A) with the likelihood of the data (B) to produce a posterior probability distribution on trees P(A|B).