Dimitri Theodoratos

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In the data warehousing approach to the integration of data from multiple information sources, selected information is extracted in advance and stored in a repository. A data warehouse (DW) can therefore be seen as a set of materialized views defined over the sources. When a query is posed, it is evaluated locally, using the materialized views, without(More)
A Data Warehouse (DW) can be seen as a set of materialized views de ned over remote source relations. During the initial design and evolution of a DW, the DW designer is faced, on many occasions, with the problem of selecting views to materialize in the DW. This problem has been addressed for di erent classes of queries/views, and with di erent design(More)
A Data Warehouse (DW) can be used to integrate data from multiple distributed data sources. A DW can be seen as a set of materialized views that determine its schema and its content in terms of the schema and the content of the data sources. DW applications require high query performance. For this reason, the design of a typical DW consists of selecting(More)
OBJECTIVE To develop a semantic representation for clinical research eligibility criteria to automate semistructured information extraction from eligibility criteria text. MATERIALS AND METHODS An analysis pipeline called eligibility criteria extraction and representation (EliXR) was developed that integrates syntactic parsing and tree pattern mining to(More)
In the data warehousing approach to the integration of data from multiple information sources, selected information is extracted in advance and stored in a repository. A data warehouse (DW) can therefore be seen as a set of materialized views deened over the sources. When a query is posed, it is evaluated locally, using the materialized views, without(More)
Nowadays, huge volumes of data are organized or exported in a tree-structured form. Querying capabilities are provided through queries that are based on branching path expression. Even for a single knowledge domain structural differences raise difficulties for querying data sources in a uniform way. In this paper, we present a method for semantically(More)
A data warehouse (DW) can be seen as a set of materialized views defined over remote base relations. When a query is posed, it is evaluated locally, using the materialized views, without accessing the original information sources. The DWs are dynamic entities that evolve continuously over time. As time passes, new queries need to be answered by them. Some(More)
On-line analytical processing (OLAP) is a technology that encompasses applications requiring a multidimensional and hierarchical view of data. OLAP applications often require fast response time to complex grouping/aggregation queries on enormous quantities of data. Commercial relational database management systems use mainly multiple one-dimensional indexes(More)