Example of a rule set generated by BioHEL. Rule sets are generated by BioHEL to classify samples. The combination of rules in the rules sets are used to assign samples to their respective treatment groups. Each rule contains one or more gene and an expression value which each gene should either be above or below, depending on the rule. At the end of each line is the group to which each rule relates. For example, the 1st rule of the rule set shown classifies all samples as belonging to the OA class if the value of the gene attribute 207211_at is greater than 100.