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| en:pojmy:lemma [2016/12/09 21:35] – [Lemmatizace] veronikapojarova | en:pojmy:lemma [2022/04/20 14:07] (current) – [Sublemma] lukes |
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| The lemma as a unit originates from an abstraction of a [[en:pojmy:word|word form's]] morphological characteristics, and represents a set of forms which have the same root and differ only on their respective morphological affixes or orthographic form. In some approaches, the selected morphological variants are also associated with the lemma. | The lemma as a unit originates from an abstraction of a [[en:pojmy:word|word form's]] morphological characteristics, and represents a set of forms which have the same root and differ only on their respective morphological affixes or orthographic form. In some approaches, the selected morphological variants are also associated with the lemma. |
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| | ===== Sublemma ===== |
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| | Starting with the SYN2020 corpus, Czech corpora feature two-level lemmatization: each form is given a sublemma attribute in addition to the lemma attribute. While a lemma may include multiple variants of a single word (e.g. the lemma //filozof// represents all forms with both //filozof// and //filosof// stems), sublemmas delimit subgroups of forms according to this alternation (the sublemma //filozof// represents only forms with the stem //filozof//, while the sublemma //filosof// represents only forms with the stem //filosof//). If the word has no variants, the sublemma is identical to the lemma (e.g. the lemma //kniha// represents the same set of forms as the sublemma //kniha//). |
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| | Different types of variants are handled as sublemmas (e.g. //mýdlo/mejdlo//, //okno/vokno//, //citron/citrón//, //email/e-mail//, //myslet/myslit//, //mýt/mejt//, //péci/péct/píct//, //kuchyně/kuchyň//, //antivirus/antivir//, //sedm/sedum//, //tenhle/tendle/tenle//, //ačkoli/ačkoliv//, proper names //Robert/Róbert/Roberto//, //Atény/Athény//). Sublemmas are also used to distinguish some specific groups of forms that are subsumed under one lemma (e.g. negated forms of adjectives and adverbs //černý/nečerný//, //hezky/nehezky//, short forms of adjectives //mladý/mlád//, suppletive forms //dobře/lépe/líp//, //člověk/lidé//). |
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| ===== The link between a lemma and lexeme ===== | ===== The link between a lemma and lexeme ===== |
| ==== Problems with lemmatization ==== | ==== Problems with lemmatization ==== |
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| Velkým lingvistickým i počítačovým problémem je lemmatizace víceslovných spojení. Jiným neřešeným problémem při automatické lemmatizaci je lemmatizace všech tvarů pod jediné lemma i tam, kde to není patřičné: např. zdvořilá prosba o dovolení projít //Dovolíte?// se neodráží v žádném z registrovaných významů slova //dovolit//, protože není součástí výlučně morfologické lemmatizace. Podobné je to i u frazémů, kde nelze tvar //holičkách// (frazému //nechat na holičkách//) lemmatizovat jako //holičky// (tvar, který navíc vůbec neexistuje). | One of the biggest linguistic and computational problems is the lemmatization of multiword expressions. Another problem of automatic lemmatization which remains unsolved is the lemmatization of all forms under one lemma even in cases where it is not appropriate e.g. //Cheers!//, when no registered meaning of the word //cheer// corresponds with the pragmatic meaning, because it does not fall under strictly morphological lemmatization. |
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| ==== The lemmatization process ==== | ==== The lemmatization process ==== |
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| Automatickou lemmatizaci provádí počítačový program zvaný //lemmatizátor//, který bývá součástí morfologického [[pojmy:tag|taggeru]], provádějícího morfologickou [[pojmy:desambiguace|desambiguaci]] textu. Smyslem lemmatizace je jednak identifikovat v daném kontextu náležitý lexém u homonymních slovních tvarů, jednak umožnit uživateli pracovat nikoli jen se slovními tvary, nýbrž i s lemmaty jakožto reprezentanty příslušných lexémů a jejich paradigmat, což mu podstatně usnadňuje práci s korpusem. | Automatic lemmatization is done by a computer program called a //lemmatizátor//, which is often part of a morphological [[en:pojmy:tag|tagger]] carrying out the [[en:pojmy:desambiguace|disambiguation]] of the text. The purpose of lemmatization is firstly to identify in a given context the appropriate lexeme among homonymous word forms, and secondly to enable the user to work not only with word forms, but also lemmas as representations of the given lexemes and their paradigms, all of which facilitates work with the corpus. |
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| ==== Related links ==== | ==== Related links ==== |
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| <WRAP round box 49%> | <WRAP round box 49%> |
| [[en:pojmy:anotace|Annotation]] • [[en:pojmy:desambiguace|Disambiguation]] • [[en:pojmy:tag|Tags and tagging]] • [[en:pojmy:word|Word form | [[en:pojmy:anotace|Annotation]] • [[en:pojmy:desambiguace|Disambiguation]] • [[en:pojmy:tag|Tags and tagging]] • [[en:pojmy:word|Word form]] |
| </WRAP> | </WRAP> |
