I. Introduction
Today, many people are constantly using user-generated and commercially generated recipe sites, such as Food.com
Food.com http://www.food.com/
(U.S.), Mis RecetasMis Recetas http://www.misrecetas.com/
(Hispanic), Beitai ChufangBeitaichufang http://www.beitaichufang.com/
(China) and CookpadCookpad http://cookpad.com/
(Japan), when they prepare their meals. Users search for recipes for their meals from the recipe sites. When a user searches for a recipe, the user poses queries of two types, typically incorporating food names such as beef stew or lasagna, and ingredient names such as chicken, cabbage, or onions. Maruha-Nichiro Holdings investigated which query is more used when users search recipes posted on recipe sites[1]. Results show that ingredient keywords are used more often than food name keywords. In fact, ingredient names account for 75% of all keywords. Therefore, when users use recipe sites, they input an ingredient name as a query. However, when they search for a recipe using an ingredient name, they are often deluged by similar recipes which use the same ingredients. Consequently, they become confused. Such similar recipes impede a user's recipe searches. For instance, when a user inputs “Chicken and Onion” in Cookpad, a famous Japanese user-generated recipe site, the search results extend to more than 46,000 pages. Numerous similar pages are found. The similar pages which have become coincidentally similar or which are plagiarized. The resultant “information overload” confuses users.