German grammar with the natural gender of what is described. However, since the diminutive forms ending in "-chen" or "-lein" are grammatically neuter, there exist several notable counterexamples such as "das Mädchen" ("girl") and "das Fräulein" ("miss"). Thus these are not illogical, whereas "das Weib" (old, regional or anthropological: woman; a cognate of the English "wife") is really an exception. Furthermore, in German, the gender of nouns without natural gender is not predictable. For example, the three common pieces of cutlery all have different genders: "das Messer" ("knife") is neuter, "die Gabel" ("fork") is feminine, and "der Löffel" ("spoon") is masculine. Students
Item-item collaborative filtering Item-item collaborative filtering Item-item collaborative filtering, or item-based, or item-to-item, is a form of collaborative filtering for recommender systems based on the similarity between items calculated using people's ratings of those items. Item-item collaborative filtering was invented and used by Amazon.com in 1998. It was first published in an academic conference in 2001. The authors of that paper, Badrul Sarwar, George Karypis, Joseph Konstan, and John Riedl, won the 2016 "Test of Time Award" for their paper "Item-based collaborative filtering recommendation algorithms". The International World Wide Web Conference committee stated that "this outstanding paper has had a considerable real-world impact".