Abstract: In a data-replication system, multi-way synchronization of copies of the data at different devices is achieved by employing a non-destructive data model. In this model, each replicated data object is represented by a revision graph, and every operation that is performed on a data object, e.g. a revision of data content or deletion of the object, is represented by adding a node to a revision graph at the device where the change is made. Synchronization between multiple devices is achieved by applying a graph union operator. Since the union operator is commutative and associative, it avoids the limitations normally associated with the order in which updates occur. A synchronization enforcement mechanism restricts the situations in which the nodes of a graph can be deleted, to thereby ensure integrity of the data throughout its useful life cycle.

Abstract: In a metasearch conducted across multiple document collections, a multi-phase approach is employed in which local and global statistics are dynamically exchanged between the search engines and the metasearch engine in response to a user's query. In the first phase, the query is transmitted to the search engines from the metasearch engine, and each search engine computes or retrieves previously-computed local statistics for those terms in its associated document collection. In the second phase, each search engine returns its local statistics. A third phase consists of computing metacollection level statistics at the metasearch engine, based upon the information contained in the local statistics. The metacollection level statistics are disseminated to the search engines. In the final phase, the search engines rank the documents in their respective collections pursuant to the metacollection level statistics, and transmit the rankings to the metasearch engine.

Abstract: In a data-replication system, multi-way synchronization of copies of the data at different devices is achieved by employing a non-destructive data model. In this model, each replicated data object is represented by a revision graph, and every operation that is performed on a data object, e.g. a revision of data content or deletion of the object, is represented by adding a node to a revision graph at the device where the change is made. Synchronization between multiple devices is achieved by applying a graph union operator. Since the union operator is commutative and associative, it avoids the limitations normally associated with the order in which updates occur. A synchronization enforcement mechanism restricts the situations in which the nodes of a graph can be deleted, to thereby ensure integrity of the data throughout its useful life cycle.

Abstract: In a metasearch conducted across multiple document collections, a multi-phase approach is employed in which local and global statistics are dynamically exchanged between the search engines and the metasearch engine in response to a user's query. In the first phase, the query is transmitted to the search engines from the metasearch engine, and each search engine computes or retrieves previously-computed local statistics for those terms in its associated document collection. In the second phase, each search engine returns its local statistics. A third phase consists of computing metacollection level statistics at the metasearch engine, based upon the information contained in the local statistics. The metacollection level statistics are disseminated to the search engines. In the final phase, the search engines rank the documents in their respective collections pursuant to the metacollection level statistics, and transmit the rankings to the metasearch engine.