Learn More
Compressed bitmap indexes are increasingly used for efficiently querying very large and complex databases. The Word Aligned Hybrid (WAH) bitmap compression scheme is commonly recognized as the most efficient compression scheme in terms of CPU efficiency. However, WAH compressed bitmaps use a lot of storage space. This paper presents the Position List Word(More)
On-line analytical processing (OLAP) systems considerably improve data analysis and are finding widespread use. OLAP systems typically employ multidimensional data models to structure their data. This paper identifies 11 modeling requirements for multidimensional data models. These requirements are derived from an assessment of complex data found in(More)
With the recent and continuing advances in areas such as wireless communications and positioning technologies, mobile, location-based services are becoming possible. % Such services deliver loca\-tion-dependent content to their users. More specifically, these services may capture the movements of their users in multidimensional databases, and their delivery(More)
csj ¡ afc ¡ tbp¡ pfoser¡ simas ¡ tryfona¢ Abstract. We are heading rapidly towards a global computing and information infrastructure that will contain billions of wirelessly connected devices, many of which will offer so-called location-based services to their mobile users always and everywhere. Indeed, users will soon take ubiquitous wireless access to(More)
Any software made available via TIMECENTER is provided " as is " and without any express or implied warranties , including, without limitation, the implied warranty of merchantability and fitness for a particular purpose. The TIMECENTER icon on the cover combines two " arrows. " These " arrows " are letters in the so-called Rune alphabet used one millennium(More)
On-Line Analytical Processing (OLAP) based on a dimensional view of data is being used increasingly in traditional business applications as well as in applications such as health care for the purpose of analyzing very large amounts of data. Pre-aggregation, the prior materializa-tion of aggregate queries for later use, is an essential technique for ensuring(More)
On-Line Analytical Processing (OLAP) enables analysts to gain insight into data through fast and interactive access to a variety of possible views on information, organized in a dimensional model. The demand for data integration is rapidly becoming larger as more and more information sources appear in modern enterprises. In the data warehousing approach,(More)
The popularity of embedded positioning technologies in mobile devices and the development of mobile communication technology have paved the way for powerful location-based services (LBSs). To make LBSs useful and user- friendly, heavy use is made of context information, including patterns in user location data which are extracted by data mining methods.(More)
This paper describes the convergence of some of the most influential technologies in the last few years, namely data warehousing (DW), on-line analytical processing (OLAP), and the Semantic Web (SW). OLAP is used by enterprises to derive important business-critical knowledge from data inside the company. However, the most interesting OLAP queries can no(More)