For many RE applications, such as knowledge base population, patterns are not only relevant if they express the target relation explicitly, but also if they extract facts from which the target relation can be inferred.
for example, all patterns below can be utilized for extracting pairs of people who are or were involved in a marriage relation: P1: PERSON 1 <marry> PERSON 2 1 P2: PERSON 1 <be widow of> PERSON 2 P3: PERSON 1 <divorce from> PERSON 2 only pattern P1 expresses the target relation explicitly.