For simplicity,we assume that skylines are computedwith respect tomin con- ditions on all dimensions; however, all methods discussed can be applied with any combination of conditions. Using the min condition, a point pi dominates1 another point pj if and only if the coordinate of pi on any axis is not larger than the corresponding coordinate of pj . Informally, this implies that pi is preferable to pj according to any preference (scoring) function which is monotone on all attributes. For instance, hotel a in Figure 1 is better than hotels b and e since it is closer to the beach and cheaper (independently of the relative importance.
