Researchers in [12] carried out a research to retrieve
English documents relevant to Persian queries using
bilingual ontologies to annotate the documents and queries.
A bilingual ontology consists of an ontology and a bilingual
dictionary. Ontology is a formal, explicit specification of a
shared conceptualization. It contains a set of distinct and
identified concepts related by a set of relations [13]. They
use the ontology to expand the query with related terms in
pre and post translation expansion and the combined
approach significantly improves cross-lingual performance.