The M-tree is an index structure that can be used for the efficient resolution of similarity queries on complex objects to be compared using an arbitrary metric, i.e. a distance function d that satisfies the positivity, symmetry, and triangle inequality p
Search engine users click the results listings' top entry much more often than can be explained by relevancy ratings. Once again, people tend to stick to the defaults.
ConceptNet is a freely available commonsense knowledgebase and natural-language-processing toolkit which supports many practical textual-reasoning tasks over real-world documents right out-of-the-box.