Semantic similarity functions and measures

Similarity is the process through which two or more objects are compared in order to identify to what extent they are alike. This is useful, for instance, when there is the need to identify common elements among a set of objects or when a new object has to be classified w.r.t. the others. Similarity is a very generic notion spanning among different disciplines from psychology to computer science. In this paper, the focus will be on computational methods that exploit ontologies or search engines as primary source of «background» knowledge. In particular, after surveying on the most popular similarity measures recently proposed, the Similarity Library will be presented, which has the aim to provide researchers and practitioners with a flexible tool encompassing several similarity measures both between words and sentences.