IDOL 12.13

# Linguistic Adjustments

After IDOL Server has processed the tokens to remove any that you do not want to index, it indexes the remaining tokens. During this process, it modifies the tokens to make it easier to return the correct documents. This involves the following processes:

- Stemming

- Character Normalization

- Transliteration

## Stemming

Main Topic: Stemming

In many languages, a related set of words have a common root. For example, help, helping, helpful and helped, all stem from the common root help. You can reduce words to their common root without losing meaning.

The IDOL stemming algorithm reduces all words to their stem, and indexes the stem. This process allows you to search for a word, and return documents with related concepts that do not specifically include that word.

## Character Normalization

In some languages, there is more than one way to represent a character. For example:

- the Roman alphabet has uppercase and lowercase forms of all letters.

- the Japanese katakana script can have full width or half width characters.

- the Chinese language has two scripts, usually known as Chinese Traditional and Chinese Simplified.

- languages with multibyte scripts sometimes use multibyte versions of Latin characters such as punctuation or numeric digits.

IDOL Server uses canonicalization to ensure that it treats all character forms equally. It automatically converts to an internationally recognized canonical form. Retrieval then matches all versions of a character.

Character normalization is controlled by the same configuration settings as Transliteration.

## Transliteration

Transliteration is like Character Normalization in that it aims to map sets of characters to a standard form so that a search for different forms match documents containing any of those forms. An important example is the removal of accents from letters so that a search for cafe matches documents containing café, and the reverse. Similarly, the German letter ß is transliterated to ss.

Transliteration schemes differ by language. For example in German, the letter ö transliterates to oe, whereas in Swedish it transliterates to o. Several languages that use non-Roman scripts can also be transliterated to Roman. For example in Russian, IDOL transliterates Владимир to Vladimir. For details of the transliteration schemes used, see Transliteration Tables.

When you have multiple languages in your server, Micro Focus recommends setting `GenericTransliteration` to `True`. See Cross-Lingual Search.

NOTE: Transliteration affects only the characters used to represent a word. IDOL Server does not translate terms from one language to another.

Turn Transliteration Off

Several languages have unusual linguistic behavior, such that even if you set `Transliteration` to `False` for that language, some characters are still transliterated. To prevent all transliteration, set:

    [LanguageTypes]
    GenericTransliteration=True

and then set `Transliteration` to `False` in the individual language sections.

Related Topics

- Advanced Tokenization

- Stemming

- Order of Language Processes

© Copyright 2022 Micro Focus or one of its affiliates
Version 12.13 | Last updated October 2022

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Product: IDOL 12.13

Topic Title: Linguistic Adjustments