Valid(rule(sale_house, ought_to_be_done(continuation_contract)))
Valid(rule(sale_house, ought_to_be_done(continuation_contract)))
Valid(rule(protects_inhabitants(act), ought_to_be_done(act)))
Valid(rule(?party_bound_by_contract, ?ought_to_be_done(continuation_contract)))
Rules and principles are both represented as RBL-rules.