Applicability
For all sentences Fact and State_of_affairs,
a. Applicable(rule(condition, conclusion), fact, state_of_affairs) is true if and only if Reason(fact, applies(rule(condition, conclusion), fact, state_of_affairs)) is true.
b. If Applicable(rule(condition, conclusion), fact, state_of_affairs) is true, then Fact is true.
If and only if a rule is applicable, the fact that makes the rule applicable is a reason to apply the rule.
A rule can only be applicable if its condition is satisfied.