2.3. Generalization
As was mentioned earlier, the main advantage of
PDL2 is that it needs not rely on some external source
for its rules. Rather, it may inductively discover those
rules from a set of observations. Even with a simple
generalization rule, such as the dropping condition
rule [14], the system is able to make a useful inductive
leap (see Section 4). The process of generalization
allows the discovery of rules that may not have been
supplied as precepts (if any were) by an external
source, as well as the potential modification of existing
rules