The C50 R package fits Quinlan's C5.0 classification model based on the source of from www.rulequest.com. Some of the functionality is based on

• Quinlan. C4.5: Programs For Machine Learning (1993b) Morgan Kaufmann Publishers Inc. San Francisco, CA

Other resources:

• More details on C5.0 can be found in Applied Predictive Modeling.
• A presentation on the model can be found here

To install the production version of the package, use:

install.packages("C50")

and to install the development version, use

require("devtools")
install_github("topepo/C5.0")