Saga Lemmatizer stage uses a dictionary file to identify words and reduce them to their basic form. For example it will identify that "running" is a verb form (gerund) and will reduce it to its base infinitive form "run".
The Lemmatizer will also expand the word to its synonyms in case there are synonyms available in the dictionary.
An important note here is that Saga Lemmatizer Stage code is agnostic to what reductions or expansions it uses. The set of reductions and expansions which are called Relationship Types are defined in the dictionary file and in the Lemmatizer configuration.
This means that when creating the dictionary file for each language, we need to be careful to understand which relationship types we want the lemmatizer to use and make sure to include them in the dictionary file.
In order to produce the dictionary file an internal tool called "Wiktionary Dump Parser" is used. In addition this tool uses an open source library called "Java Wiktionary Library" or "JWKTL" that helps with the parsing of the Wiktionary.
In the following diagram you can see different components and different stages the tool uses to produce a dictionary file:
Stage 1: Wiktionary dump parser tool, using JWKL, will parse the language specific Wiktionary dump file and produce an index in Oracle Berkeley DB format.
Stage 2: Wiktionary dump parser tool, reads the contents in the index, transform them and stores entries in a Mongo DB collection.
Stage 3: Wiktionary dump parser tool, reads and parses entries stored in Mongo DB and produces a JSON file in a format that SAGA lemmatizer can use.
On the following steps you will know where to get Wiktionary dump files, what code you need to add/modify to support an additional language and how to test your new generated dictionary file.
Step-by-step guide
Step 1: Download Wiktionary dump file
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