Rationing in the United Kingdom meat, tea, jam, biscuits, breakfast cereals, cheese, eggs, lard, milk, and canned and dried fruit. In June 1942 the Combined Food Board was set up by Great Britain and the United States to coordinate the world supply of food to the Allies, with special attention to flows from the U.S. and Canada to Britain. Almost all foods apart from vegetables and bread were rationed by August 1942. Strict rationing inevitably created a black market. Almost all controlled items were rationed by weight but meat was rationed by price. Fresh vegetables and fruit were not rationed but supplies were limited. Some
Item-item collaborative filtering Earlier collaborative filtering systems based on rating similarity between users (known as user-user collaborative filtering) had several problems: Item-item models resolve these problems in systems that have more users than items. Item-item models use rating distributions "per item", not "per user". With more users than items, each item tends to have more ratings than each user, so an item's average rating usually doesn't change quickly. This leads to more stable rating distributions in the model, so the model doesn't have to be rebuilt as often. When users consume and then rate an item, that item's similar items are picked from