Restricted inflectional form generation in management of morphological keyword variation

Word form normalization through lemmatization or stemming is a standard procedure in information retrieval because morphological variation needs to be accounted for and several languages are morphologically non-trivial. Lemmatization is effective but often requires expensive resources. Stemming is also effective in most contexts, generally almost as good as lemmatization and typically much less expensive; besides it also has a query expansion effect. However, in both approaches the idea is to turn many inflectional word forms to a single lemma or stem both in the database index and in queries. This means extra effort in creating database indexes. In this paper we take an opposite approach: we leave the database index un-normalized and enrich the queries to cover for surface form variation of keywords. A potential penalty of the approach would be long queries and slow processing. However, we show that it only matters to cover a negligible number of possible surface forms even in morpho...

• Type: Journal
• Year: 2007
• Where: IR
• Authors: Kimmo Kettunen, Eija Airio, Kalervo Järvelin
• Keywords: IR 2007, Natural Language Processing, Surface Form, Word Form Normalization, Word Forms