Christmas cracker tradition of wearing festive hats is believed to date back to Roman times and the Saturnalia celebrations, which also involved decorative headgear. Christmas crackers are also associated with Knut's parties, held in Sweden at the end of the Christmas season. The "Oxford English Dictionary" records the use of "cracker bonbons" and the pulling of "crackers" from 1847. Tradition tells of how Tom Smith of London invented crackers in 1847. He created the crackers as a development of his bon-bon sweets, which he sold in a twist of paper (the origins of the traditional sweet-wrapper). As sales of bon-bons slumped, Smith
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".