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https://github.com/google-research/turkish-morphology

A two-level morphological analyzer for Turkish.
https://github.com/google-research/turkish-morphology

google morphological-analyser morphology natural-language-processing natural-language-understanding nlp turkish

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A two-level morphological analyzer for Turkish.

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README 

        
# Turkish Morphology



![](https://github.com/google-research/turkish-morphology/workflows/Linux%20Build%20Status/badge.svg)



A two-level morphological analyzer for Turkish.



This is not an official Google product.



## Components



This implementation is composed of three layers:



* **Lexicons:**



  This layer includes wide-coverage [Turkish lexicons][3] which are manually

  annotated and validated for part-of-speech and morphophonemic irregularities.

  They are intended to be used in building Turkish natural language processing

  tools, such as morphological analyzers. The set of base lexicons that we

  provide includes annotated lexical items for 47,202 words. The tagsets and

  the annotation scheme are described in the [lexicon annotation guidelines][4].



* **Morphotactics:**



  This layer includes [a set of FST definitions][5] which are implemented in a

  custom format which is similar to AT&T FSM format (only difference being that

  we can use strings as state names and input/output labels for each transition

  instead of integers). With each of these FSTs we define the suffixation

  patterns and the morpheme inventories together with their corresponding

  output morphological feature category-value pairs for a given part-of-speech.

  Overall morphotactic model and the morphological feature category-value

  tagsets are described in the [morphotactic model guidelines][6].



* **Morphophonemics:**



  This layer includes [a set of Thrax grammars][7], where each implements a

  standalone morphophonemic process (such as vowel harmony, vowel drop,

  consonant voicing and consonant drop and so on). Composition of the exported

  FSTs defined in these Thrax grammars yield the [morphophonemic model][8] of

  Turkish.



The first level of the morphological analysis is implemented by the

morphophonemic model, which takes a Turkish word and transforms it into the

intermediate representation. The output of the first level is all possible

hypotheses of word stem annotations with morphophonemic irregularities followed

by the meta-morphemes that correspond to the suffixes that are realized in the

surface form.



```

Input: affında

Output: af"+SH+NDA

```



Lexicon entries and morphotactic FST definitions are composed and compiled into

a single FST which acts as the second level of the morphological analysis,

namely the morphotactic model. Morphotactic model takes the intermediate

tape as the input and transforms it to all possible human-readable morphological

analyses that can be generated from the hypotheses generated by the first level.



```

Input: af"+SH+NDA

Output: (af[NN]+[PersonNumber=A3sg]+Hn[Possessive=P2sg]+NDA[Case=Loc])+[Proper=False]

```



See [Interpreting Human-Readable Morphological Analysis][12] section for a

description of such human-readable morphological analysis.



## How to Parse Words



To morphologically parse a word, simply run below from the project root

directory.



```

bazel run -c opt scripts:print_analyses -- --word=[WORD_TO_PARSE]

```



This will morphologically parse the input word against the two-level

morphological analyzer and output a set of human-readable morphological

analysis, as such:



```

bazel run -c opt scripts:print_analyses -- --word=geldiğinde

> Morphological analyses for the word 'geldiğinde':

> (gel[VB]+[Polarity=Pos])([NOMP]-DHk[Derivation=PastNom]+[PersonNumber=A3sg]+Hn[Possessive=P2sg]+NDA[Case=Loc]+[Copula=PresCop]+[PersonNumber=V3pl])+[Proper=False]

> (gel[VB]+[Polarity=Pos])([NOMP]-DHk[Derivation=PastNom]+[PersonNumber=A3sg]+Hn[Possessive=P2sg]+NDA[Case=Loc]+[Copula=PresCop]+[PersonNumber=V3pl])+[Proper=True]

> (gel[VB]+[Polarity=Pos])([NOMP]-DHk[Derivation=PastNom]+[PersonNumber=A3sg]+Hn[Possessive=P2sg]+NDA[Case=Loc]+[Copula=PresCop]+[PersonNumber=V3sg])+[Proper=False]

> (gel[VB]+[Polarity=Pos])([NOMP]-DHk[Derivation=PastNom]+[PersonNumber=A3sg]+Hn[Possessive=P2sg]+NDA[Case=Loc]+[Copula=PresCop]+[PersonNumber=V3sg])+[Proper=True]

> (gel[VB]+[Polarity=Pos])([NOMP]-DHk[Derivation=PastNom]+[PersonNumber=A3sg]+SH[Possessive=P3sg]+NDA[Case=Loc]+[Copula=PresCop]+[PersonNumber=V3pl])+[Proper=False]

> (gel[VB]+[Polarity=Pos])([NOMP]-DHk[Derivation=PastNom]+[PersonNumber=A3sg]+SH[Possessive=P3sg]+NDA[Case=Loc]+[Copula=PresCop]+[PersonNumber=V3pl])+[Proper=True]

> (gel[VB]+[Polarity=Pos])([NOMP]-DHk[Derivation=PastNom]+[PersonNumber=A3sg]+SH[Possessive=P3sg]+NDA[Case=Loc]+[Copula=PresCop]+[PersonNumber=V3sg])+[Proper=False]

> (gel[VB]+[Polarity=Pos])([NOMP]-DHk[Derivation=PastNom]+[PersonNumber=A3sg]+SH[Possessive=P3sg]+NDA[Case=Loc]+[Copula=PresCop]+[PersonNumber=V3sg])+[Proper=True]

> (gel[VB]+[Polarity=Pos])([VN]-DHk[Derivation=PastNom]+[PersonNumber=A3sg]+Hn[Possessive=P2sg]+NDA[Case=Loc])+[Proper=False]

> (gel[VB]+[Polarity=Pos])([VN]-DHk[Derivation=PastNom]+[PersonNumber=A3sg]+Hn[Possessive=P2sg]+NDA[Case=Loc])+[Proper=True]

> (gel[VB]+[Polarity=Pos])([VN]-DHk[Derivation=PastNom]+[PersonNumber=A3sg]+SH[Possessive=P3sg]+NDA[Case=Loc])+[Proper=False]

> (gel[VB]+[Polarity=Pos])([VN]-DHk[Derivation=PastNom]+[PersonNumber=A3sg]+SH[Possessive=P3sg]+NDA[Case=Loc])+[Proper=True]

```



If the input string is not accepted as a Turkish word, morphological analyzer

outputs an empty result.



```

bazel run -c opt scripts:print_analyses -- --word=foo

> 'foo' is not accepted as a Turkish word

```



## Interpreting Human-Readable Morphological Analysis



An example output human-readable morphological analysis is as follows;



**Input Word** (*evlerindekilerin* = those that belongs to ones in their

homes):



```

bazel run -c opt scripts:print_analyses -- --word=evlerindekilerin

```



**Sample Output Morphological Analysis String**:



```

(ev[NN]+[PersonNumber=A3sg]+lArH[Possessive=P3pl]+NDA[Case=Loc])([PRF]-ki[Derivation=Pron]+lAr[PersonNumber=A3sg]+[Possessive=Pnon]+NHn[Case=Gen])+[Proper=False]

```



Human-readable morphological analyses can be decomposed into parts:



* **Inflectional groups:**



  Each human-readable morphological analysis is composed of inflectional groups.

  An inflectional group is a sub-word span, and it is created by affixation of a

  derivational morpheme. Inflectional group analyses are enclosed in

  parenthesis. Above example contains two inflectional groups:

   - `(ev[NN]+[PersonNumber=A3sg]+lArH[Possessive=P3pl]+NDA[Case=Loc])`

   - `([PRF]-ki[Derivation=Pron]+lAr[PersonNumber=A3pl]+[Possessive=Pnon]+NHn[Case=Gen])`



* **Word stem:**



  First inflectional group contains the word stem (e.g. `ev` is the root form

  for the above example input word *evlerindekilerin*).



* **Analysis of morphemes:**



  Within each inflectional group meta-morphemes and

  their corresponding morphological feature category-value tags are separated

  with either `+` or `-` delimiters. (e.g. `+[PersonNumber=A3sg]`,

  `+lArH[Possessive=P3pl]`, `-ki[Derivation=Pron]`, etc.). Strings that are

  immediate followers of the delimiters `+` or `-` are the meta-morphemes (e.g.

  `NDA` is the meta-morpheme in morpheme analysis `+NDA[Case=Loc]`).

  Morphological feature category-value tags are enclosed in brackets right

  after the meta-morphemes (e.g. `Case` is the feature category and `Loc` is

  feature value in morpheme analysis `+NDA[Case=Loc]`).



* **Part-of-speech:**



  Part-of-speech tag of each inflectional group is the first bracketed tag of

  the inflectional group (e.g. `NN` is the part-of-speech of the first

  inflectional group and `PRF` is for the second inflectional group).



* **Inflectional vs. Derivational morphemes:**



  Meta-morphemes that are separated with `+` delimiter do not create a new

  inflectional group. They are inflectional morphemes (e.g.

  `+[PersonNumber=A3sg]`, `+NDA[Case=Loc]`, `+[Possessive=Pnon]`, etc.).

  Meta-morphemes that are separated with `-` delimiter create a new

  inflectional group. They are the derivational morphemes (e.g.

  `-ki[Derivation=Pron]`). Therefore, first meta-morpheme in an inflectional

  group always follows the delimiter `-`, but not `+`.



* **Surface realization of inflections:**



  Some meta-morphemes are not realized in the surface form. These meta-morphemes

  do not correspond to a span of characters in the input word. For them we do

  not output any meta-morpheme in the morpheme analysis (e.g.

  `+lArH[Possessive=P3pl]` and `+NDA[Case=Loc]` are realized in the surface

  form, thus they have explicit meta-morphemes `lArH` and `NDA` in their

  morpheme analysis. However, `+[PersonNumber=A3sg]` and `+[Possessive=Pnon]`

  are not realized in the surface form, therefore only morphological feature

  category-value tags are output for them in their morpheme analysis).



* **Surface realization of derivations:**



  Derivational morphemes must always realize in the surface form. They always

  correspond to a span of characters in the input word. Therefore, we always

  output non-empty meta-morphemes in the corresponding morpheme analysis of

  derivational morphemes. Meaning that no zero-derivations are allowed in the

  morphotactic model.



* **Proper noun analysis:**



  An optional proper noun feature analysis is output at the end of each

  inflectional group (e.g. `+[Proper=False]` which follows the second

  inflectional group). Proper noun feature category can take two values `True`

  or `False`. If it is specified as `True`, the inflectional group that it

  follows is considered to be a part of a proper noun. This feature is used to

  capture the internal structure of proper nouns that are composed of multiple

  words (e.g. for multi-word movie names the true part-of-speech and

  morphological feature of words that compose a multi-word movie name can be

  annotated, while marking the fact that they are part of a proper noun using

  this feature).



  Proper noun feature analysis is omitted for some of the inflectional groups

  to have a compact representation and to minimize the number of morphological

  analyses generated by the morphological analyzer. In such cases, proper noun

  feature analysis of an inflectional group applies to all preceding

  inflectional groups that does not have one (e.g. first inflectional group of

  the above example inherits its proper noun feature analysis `Proper=False`

  from the second inflectional group).



## Python API



We also provide a [Python API][15] that can be used to morphologically analyze

Turkish words, generate Turkish word forms from morphological analyses, parse

human-readable morphological analyses into protobuf messages, validate their

structural well-formedness and to generate human-readable analyses from them.

You can see some example use cases in [`//examples`][17].



If you are using [Bazel][16], you can depend on this repository as an external

dependency of your project by adding the following to your WORKSPACE file:



```

git_repository(

  name = "google_research_turkish_morphology",

  remote = "https://github.com/google-research/turkish-morphology.git",

  tag = "{version-tag}",

)

```



Then, you can simply use

`@google_research_turkish_morphology//turkish_morphology:analyze`

(or other modules of the API) as a dependecy of your relevant `py_library` or

`py_binary` BUILD targets.



The API is also available on PyPi. To install the latest release from PyPi, run:



```

python3 -m pip install turkish-morphology

```



To install from source, run below from the project root directory (preferably

within a Python virtual environment):



```

bazel build //...

bazel-bin/setup install

```



## Requirements



To build and run the morphological analyzer install [Bazel version 5.0.0][9] and

[Python 3.9][10]. All other intrinsic dependencies will be imported, built and

taken care of by Bazel according to the [WORKSPACE][2] setup throughout the

first invocation of the morphological analyzer runtime. If you are installing

from PyPi, you need [pip][14].



## Citing



If you use or discuss the code, data or tools from this repository in your work,

please cite:



Öztürel, A., Kayadelen, T. & Demirşahin, I (2019, September). [A syntactically

expressive morphological analyzer for Turkish][13]. In Proceedings of the 14th

International Conference on Finite-State Methods and Natural Language

Processing (pp. 65-75).



```

@inproceedings{

    title = "A Syntactically Expressive Morphological Analyzer for Turkish",

    author = "\"{O}zt\"{u}rel, Adnan and Kayadelen, Tolga and Demir\c{s}ahin,

        I\c{s}{\i}n",

    booktitle = "Proceedings of the 14th International Conference on Finite-State

        Methods and Natural Language Processing",

    month = "23--25" # sep,

    year = "2019",

    address = "Dresden, Germany",

    publisher = "Association for Computational Linguistics",

    url = "https://www.aclweb.org/anthology/W19-3110",

    pages = "65--75",

}

```



## License



Unless otherwise noted, all original files are licensed under an

[Apache License, Version 2.0][1].



[1]: LICENSE

[2]: WORKSPACE.bazel

[3]: ./src/analyzer/lexicon/base

[4]: ./src/analyzer/lexicon/README.md

[5]: ./src/analyzer/morphotactics/model

[6]: ./src/analyzer/morphotactics/README.md

[7]: ./src/analyzer/morphophonemics

[8]: ./src/analyzer/morphophonemics/model.grm

[9]: https://docs.bazel.build/versions/master/install.html

[10]: https://www.python.org/downloads/

[12]: #interpreting-human-readable-morphological-analysis

[13]: https://www.aclweb.org/anthology/W19-3110

[14]: https://pip.pypa.io/en/stable/installing/

[15]: ./turkish_morphology

[16]: https://bazel.build/

[17]: ./examples