In papers usually Cross-Lingual Information Retrieval (CLIR) and Multi-Lingual Information Retrieval (MLIR) use equivalently or distinctly. I want to know is there any difference between these two terms?
In this paper they differentiate between these two terms as follows:
While CLIR is concerned with retrieval for given language pairs (i.e. all the documents are given in a specific language and need to be retrieved to queries in another language), MLIR is concerned with retrieval from a document collection where documents in multiple languages co-exist and need to be retrieved to a query in any language. MLIR is thus inherently more difficult than CLIR.