A Lemmatizer produces lemmas for each noun and adjective in the document contexts. A lemma is the semantic root of a word that has different inflections. For example, a lemma of geese is goose.
Use the Lemmatizer to match singular/plural and masculine/feminine versions of words.
The output from the Lemmatizer is typically used by other semantic processors in the document analysis chain.
When to Use
There are two use cases for the lemmatizer query expansion module:
• If you have configured the Ontology Matcher, Rules Matcher, Fast Rules Matcher, or Semantic Extractor for lemma matches, you must define a Lemmatizer before it in the document analysis pipeline.
• To perform lemma query expansion for languages tokenized by the Basis Tech (Extended Languages) tokenizer, you must configure the Lemmatizer semantic processor, and follow some additional steps for tokenization.