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Internet search engines have popularized the keywordbased search paradigm. While traditional database management systems offer powerful query languages, they do not allow keyword-based search. In this paper, we discuss DBXplorer, a system that enables keywordbased search in relational databases. DBXplorer has been implemented using a commercial relational(More)
We consider the problem of finding rules relating patterns in a time series to other patterns in that series, or patterns in one series to patterns in another series. A simple example is a rule such as "a period of low telephone call activity is usually followed by a sharp rise ill call vohune". Examples of rules relating two or more time series are "if the(More)
The Göttingen State and University Library provides access to digitized documents strictly for noncommercial educational, research and private purposes and makes no warranty with regard to their use for other purposes. Some of our collections are protected by copyright. Publication and/or broadcast in any form (including electronic) requires prior written(More)
Matrix decomposition methods represent a data matrix as a product of two factor matrices: one containing basis vectors that represent meaningful concepts in the data, and another describing how the observed data can be expressed as combinations of the basis vectors. Decomposition methods have been studied extensively, but many methods return real-valued(More)
Euclidean spanners are important data structures in geometric algorithm design, because they provide a means of approximating the complete Euclidean graph with only O(n) edges, so that the shortest path length between each pair of points is not more than a constant factor longer than the Euclidean distance between the points. In many applications of(More)
We study the problem of group recommendation. Recommendation is an important information exploration paradigm that retrieves interesting items for users based on their profiles and past activities. Single user recommendation has received significant attention in the past due to its extensive use in Amazon and Netflix. How to recommend to a group of users(More)
The problem of obtaining efficient answers to top-<i>k</i> queries has attracted a lot of research attention. Several algorithms and numerous variants of the top-<i>k</i> retrieval problem have been introduced in recent years. The general form of this problem requests the <i>k</i> highest ranked values from a relation, using monotone combining functions on(More)
1. Motivation Internet search engines have popularized keyword based search. While relational database systems offer powerfifl structured query languages such as SQL, there is no support for keyword search over databases. The simplicity of keyword search as a querying paradigm offers compelling values for data exploration. Specifically, keyword search does(More)
Let <italic>G=(V,E)</italic> be a <italic>n</italic>-vertex connected graph with positive edge weights. A subgraph <italic>G</italic>&#8242; is a <italic>t</italic>-spanner if for all <italic>u,v</italic><inline-equation> <f> &#8712;</f> </inline-equation><italic>V</italic>, the distance between <italic>u</italic> and <italic>v</italic> in the subgraph is(More)