+The `R` package `eratosthenes` (named after Eratosthenes of Cyrene, author of the _Chronographiai_) provides functions for chronology-building, above all to bring artifact dating within the scope of formal mathematical estimation. Hence, an investigator can obtain separate probability density functions (p.d.f.) for the production, use, and deposition of an artifact type, in addition to marginal p.d.f.s for all relative sequential events (howsover determined) and absolute constraints (howsoever defined). It uses Gibbs sampling, by now a conventional Markov Chain Monte Carlo method in archaeological chronology [@geman_stochastic_1984; @buck_bayesian_1996]. Using `Rcpp`, [@eddelbuettel_extending_2018], `eratosthenes` performs a two-step Gibbs routine, the first a preliminiary sampler to select a starting date, and a second main sampler that uses consistent batch means (CBM) as a stopping rule, given that convergence in distribution is assured [@jones_fixed-width_2006; @flegal_markov_2008]. Full reporting on the Monte Carlo standard errors (MCSE) is provided, giving an error in +/- years for each marginal density. Finally, `eratosthenes` provides functions for assessing the level of dependence of events upon each other within the joint conditional. Changes in dates brought about by any alteration in the structure of a chronology can therefore be readily evaluted. In sum, `eratosthenes` allows for expedient revision of chronologies, transparency in the definition of the full joint conditional, and statistics on the certainty of estimates via MCSE.
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