Context-sensitive ranking

Rakesh Agrawal, Ralf Rantzau, Evimaria Terzi
2006 Proceedings of the 2006 ACM SIGMOD international conference on Management of data - SIGMOD '06  
Contextual preferences take the form that item i1 is preferred to item i2 in the context of X. For example, a preference might state the choice for Nicole Kidman over Penelope Cruz in drama movies, whereas another preference might choose Penelope Cruz over Nicole Kidman in the context of Spanish dramas. Various sources provide preferences independently and thus preferences may contain cycles and contradictions. We reconcile democratically the preferences accumulated from various sources and use
more » ... them to create a priori orderings of tuples in an off-line preprocessing step. Only a few representative orders are saved, each corresponding to a set of contexts. These orders and associated contexts are used at query time to expeditiously provide ranked answers. We formally define contextual preferences, provide algorithms for creating orders and processing queries, and present experimental results that show their efficacy and practical utility. 2. Techniques for using these preferences to generate a few representative orderings of the tuples and their associated contexts. 3. Techniques for using these pre-orderings to quickly provide ranked answers to the queries taking into consideration the condition part of the query. EXAMPLE 1: Consider the movie relation with schema (title, actor, genre, language). Assume that we have the following contextual preferences (written omitting attribute names):
doi:10.1145/1142473.1142517 dblp:conf/sigmod/AgrawalRT06 fatcat:22vskpcknzgupdu6dyuumrsdhq