Annotated search and element retrieval

Abstract

Despite the great interest in diferent forms of textual an- notation (named entity extraction, semantic tagging, syntactic and setmantic parsing, etc.), there is still no consensus about which search tasks can be improved with such annotations, and what search algorithms are required to implement eficient engines to solve these tasks. We define formally two retrieval tasks in annotated collections: Annotated retrieval and element retrieval. We discuss their differences and describe eficient indexing structures, and how they can be implemented in Lucene and MG4J, two open source retrieval engines. Finally, we give a technical overview of two element retrieval use cases.