Refraction is a vital, but little understood aspect of rule engines. In a three-part article, I’ve attempted to shed some light on what it is and the various options that rule engine designers have when implementing it.
Part 1
http://geekswithblogs.net/cyoung/archive/2010/09/07/the-dimensions-of-refraction–part-1.aspx
Part 2
http://geekswithblogs.net/cyoung/archive/2010/09/07/the-dimensions-of-refraction–part-2.aspx
Part 3
http://geekswithblogs.net/cyoung/archive/2010/09/07/the-dimensions-of-refraction–part-3.aspx