What is Divide and Conquer

Location-based Skyline queries select the nearest objects to a point that best meet the user's preferences. Particularly, this chapter focuses on location-based Skyline queries over web-accessible data. Web-accessible may have geographical location and be geotagged with documents containing ratings by web users. Location-based Skyline queries may express preferences based on dynamic features such as distance and changeable ratings. In this context, distance must be recalculated when a user changes his position while the ratings must be extracted from external data sources which are updated each time a user scores an item in the Web. This chapter describes and empirically studies four solutions capable of answering location-based Skyline queries considering user's position change and information extraction from the Web inside an area search around the user. They are based on an M-Tree index and Divide & Conquer principle.