A branch of math named for him associates probabilities with degrees of (*)  belief, a paradigm of probability theory contrasted with frequentism.
This mathematician's namesake networks are directed acyclic graphs in which each node is a random variable and the edges are probabilistic dependencies. He conceived of the problem of inferring a distribution for a model about which we only know the outcomes. As more evidence becomes available, one statement named for this man updates a quantity's prior form to its posterior form; that method is called his namesake "inference." A branch of math named for him associates probabilities with degrees of (*)  belief, a paradigm of probability theory contrasted with frequentism. Spam filters use math inspired by, for 10 points, what 18th-century English statistician whose most famous theorem relates the conditional probability of  X  given  Y  to the conditional probability of  Y  given  X ?
This mathematician's namesake networks are directed acyclic graphs in which each node is a random variable and the edges are probabilistic dependencies.
Thomas  Bayes  [or  Bayes ian; or  Bayes  networks; or  Bayes'  theorem]