ABSTRACT:

With the advance of wireless communication technology, it is quite common for people to read maps or get related services from the handheld devices, like mobile phones and PDAs. Range queries, as one of the most commonly used tools, are usually posed by the users to retrieve needful data from a spatial database. However, thanks to the boundaries of communication bandwidth and hardware power of handheld devices, displaying all the results of a vary query on a handheld device is neither communication-efficient nor informative to the users. This is merely because that there are often too several results came from a range question. In read of this problem, we gift a completely unique idea that a concise illustration of a specified size for the vary query results, whereas incurring minimal data loss, shall be computed and came to the user. Such a concise vary query not solely reduces communication prices, however also offers better usability to the users, providing an chance for interactive exploration. The usefulness of the concise vary queries is confirmed by comparing it with different potential alternatives, like sampling and clustering. Unfortunately, we prove that finding the optimal representation with minimum data loss is an NP-laborious problem. Therefore, we propose many effective and nontrivial algorithms to search out a sensible approximate result. Extensive experiments on real-world knowledge have demonstrated the effectiveness and potency of the proposed techniques.