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Discovering Relative Importance of Skyline Attributes

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					    Discovering Relative Importance of
                    Skyline Attributes
                VLDB`09



1
Outline
       Introduction

       Basic Notions

       P-skyline Discovery

       Experiments

       Conclusions


    2
Introduction
       Querying databases with preferences
           All attributes are of the same importance in skyline preference
            relations
       P-skyline (P:prioritize)
           Add the notion of attribute importance




    3
(Cont.)




4
Basic Notions
       Atomic preferences (H): total orders over (single)
        attributes
       Skyline preference relation (skyH): t1 preferred to t2 if
           t1 equal or better than t2 in every attribute, and
           t1 strictly better than t2 in at least one attribute
       Skyline: the set wskyH(O) of best tuples (according to
        skyH) in a set of tuples O




    5
(Cont.)
       Prioritized skyline (p-skyline)
       p-skyline relations
           Induced by an atomic preference relation >A ∈ H



           Pareto accumulation (        equally important as   )



           Prioritized accumulation (       more important than    )




    6
(Cont.)
       Pareto      Prioritized




    7
(Cont.)
       p-graph
            represents attribute importance induced by a p-
        skyline relation
           Nodes: attributes
           Edges: from more important to less important attributes




    8
P-skyline Discovery
       Discovery of p-skyline relations from user feedback
         Problem:
         Given a set A of relevant attributes and a set H of
          atomic preferences over A, discover the relative
          importance of attributes [in the form of a p-skyline
          relation    ], based on user feedback.




    9
(Cont.)
    Computing maximal         favoring G in O
        Construct a system N of negative constraints from G and O




    10
Experiments




11
(Cont.)




12
Conclusion
    generalizing skylines to p-skylines to capture relative
     attribute importance




    13

				
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