---
title: "Compression-based Language Complexity under — Serras 2026"
description: "The authors test whether compression-based metrics of linguistic complexity (so-called Kolmogorov complexity) respond to register variation in Portuguese."
authors: ["Felipe Ribas Serras", "Marcelo Finger"]
year: 2026
venue: "Proceedings of the 17th International Conference on Computational Processing of Portuguese (PROPOR 2026) - Vol. 1"
source: "https://aclanthology.org/2026.propor-1.80/"
licence: "CC BY 4.0 (ACL Anthology)"
licence_url: "https://creativecommons.org/licenses/by/4.0/"
summary_licence: "Elamur Cosmic License"
canonical: "https://research.elamur.ai/free/papers/serras-2026-compression-based-language-complexity-under/"
---
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# Compression-based Language Complexity under Register Variation in Portuguese

**Authors:** Felipe Ribas Serras, Marcelo Finger · **Year:** 2026 · **Venue:** Proceedings of the 17th International Conference on Computational Processing of Portuguese (PROPOR 2026) - Vol. 1 · **Licence:** [CC BY 4.0 (ACL Anthology)](https://creativecommons.org/licenses/by/4.0/)

**Links:** [Publisher's page](https://aclanthology.org/2026.propor-1.80/) · [PDF](https://aclanthology.org/2026.propor-1.80.pdf)

## Summary
The authors test whether compression-based metrics of linguistic complexity (so-called Kolmogorov complexity) respond to register variation in Portuguese. This effect has already been shown for English. Such metrics are convenient because they operate on raw text and require no parsers or morphological analyzers. Complexity is estimated by how well the text compresses with the gzip and bzip2 compressors. To isolate syntactic or morphological complexity, the text is randomly distorted, and the resulting change in compressed file size is observed. The analysis is conducted at the sentence level on Brazilian Portuguese from the carol-domain-sents dataset, where register is defined by the typology of the source. Instead of a single overall test, the authors separately assess the sensitivity of each metric, as well as their joint sensitivity. The metrics systematically distinguish registers, with morphological metrics being considerably more sensitive than syntactic ones. A linear trade-off between morphological and syntactic complexity is observed, as in English. This gives Portuguese-language NLP grounds for using such metrics in text simplification, readability assessment, and register classification tasks.

## Key points
- Data: the carol-domain-sents dataset (Hugging Face, carolina-c4ai); its sentences are taken from the deduplicated Carolina Corpus of contemporary Brazilian Portuguese.
- Metrics: overall complexity equals the residuals of a linear regression of compressed text size on text length. Syntactic complexity is computed by deleting 10% of words, morphological complexity by deleting 10% of characters within words. There is also a variant of the morphological metric following Juola, in which words are replaced with numerical indices. The implementation of Serras et al. (2024a) is used.
- Morphological metrics distinguish registers considerably better than syntactic ones. Whether this is specific to Portuguese remains unclear.
- The trade-off between morphological and syntactic complexity across registers is linear, just as in English and in cross-linguistic studies.
- The authors list the following limitations: written data predominate, there are fewer registers than in the English-language experiments, the tests show only overall differences without pairwise comparisons, the metrics have poor interpretability, and the compression method requires a substantial amount of data.

*Our summary of the paper, in our own words — not its text. The work belongs to its authors; read it at the links above.*

Fields: [Linguistics & languages](https://md.research.elamur.ai/free/shelves/linguistics/)

## Cite

The paper itself, not this page. BibTeX from the library's record of the work.

```bibtex
@inproceedings{serras2026compression,
  title = {{Compression-based Language Complexity under Register Variation in Portuguese}},
  author = {Serras, Felipe Ribas and Finger, Marcelo},
  booktitle = {Proceedings of the 17th International Conference on Computational Processing of Portuguese (PROPOR 2026) - Vol. 1},
  year = {2026},
  url = {https://aclanthology.org/2026.propor-1.80/}
}
```

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## References

22 references, 0 of them with a card of ours. ↗ leads to the work, «find» searches for one we have no id for yet.

1. Patrick Juola. 2008. Assessing linguistic complexity, pages 89–108. John Benjamins Publishing Company. [find](https://scholar.google.com/scholar?q=Patrick+Juola%2E+2008%2E+Assessing+linguistic+complexity%2C+pages+89%E2%80%93108%2E+John+Benjamins+Publishing+Company%2E)
2. Christian Bentz, Ximena Gutierrez-Vasques, Olga Sozinova, and Tanja Samardžić. 2023. Complexity trade-offs and equi-complexity in natural languages: A meta-analysis. Linguistics Vanguard, 9(s1):9–25. [find](https://scholar.google.com/scholar?q=Christian+Bentz%2C+Ximena+Gutierrez%2DVasques%2C+Olga+Sozinova%2C+and+Tanja+Samard%C5%BEic%CC%81%2E+2023%2E+Complexity+trade%2Doffs+and+equi%2Dcomplexity+in+natural+languages%3A+A+meta%2Danalysis%2E+Linguistics+Vanguard%2C+9%28s1%29%3A9%E2%80%9325%2E)
3. Douglas Biber. 1988. Variation across Speech and Writing, 1st edition. Cambridge University Press. [find](https://scholar.google.com/scholar?q=Douglas+Biber%2E+1988%2E+Variation+across+Speech+and+Writing%2C+1st+edition%2E+Cambridge+University+Press%2E)
4. Douglas Biber. 1995. Dimensions of Register Variation: A Cross-Linguistic Comparison, 1st edition. Cambridge University Press. [find](https://scholar.google.com/scholar?q=Douglas+Biber%2E+1995%2E+Dimensions+of+Register+Variation%3A+A+Cross%2DLinguistic+Comparison%2C+1st+edition%2E+Cambridge+University+Press%2E)
5. Douglas Biber and Susan Conrad. 2009. Register, Genre, and Style, 1st edition. Cambridge University Press. [find](https://scholar.google.com/scholar?q=Douglas+Biber+and+Susan+Conrad%2E+2009%2E+Register%2C+Genre%2C+and+Style%2C+1st+edition%2E+Cambridge+University+Press%2E)
6. Zach Bobbitt. 2021. What is Pillai’s Trace? (Definition & Example). [https://www.statology.org/](https://www.statology.org/) pillais-trace/. Statology. Accessed: 2026-01-06. [↗](https://www.statology.org/)
7. Jacob Cohen. 2013. Statistical Power Analysis for the Behavioral Sciences. Routledge. [find](https://scholar.google.com/scholar?q=Jacob+Cohen%2E+2013%2E+Statistical+Power+Analysis+for+the+Behavioral+Sciences%2E+Routledge%2E)
8. Angela Dean, Daniel Voss, and Danel Draguljić. 2017. Design and Analysis of Experiments. Springer Texts in Statistics. Springer International Publishing, Cham. [find](https://scholar.google.com/scholar?q=Angela+Dean%2C+Daniel+Voss%2C+and+Danel+Draguljic%CC%81%2E+2017%2E+Design+and+Analysis+of+Experiments%2E+Springer+Texts+in+Statistics%2E+Springer+International+Publishing%2C+Cham%2E)
9. Katharina Ehret. 2016. An information-theoretic approach to language complexity: variation in naturalistic corpora. Ph.D. thesis, Albert-Ludwigs-Universität Freiburg. [find](https://scholar.google.com/scholar?q=Katharina+Ehret%2E+2016%2E+An+information%2Dtheoretic+approach+to+language+complexity%3A+variation+in+naturalistic+corpora%2E+Ph%2ED%2E+thesis%2C+Albert%2DLudwigs%2DUniversit%C3%A4t+Freiburg%2E)
10. Katharina Ehret. 2021. An information-theoretic view on language complexity and register variation: Compressing naturalistic corpus data. Corpus Linguistics and Linguistic Theory, 17(2):383–410. [find](https://scholar.google.com/scholar?q=Katharina+Ehret%2E+2021%2E+An+information%2Dtheoretic+view+on+language+complexity+and+register+variation%3A+Compressing+naturalistic+corpus+data%2E+Corpus+Linguistics+and+Linguistic+Theory%2C+17%282%29%3A383%E2%80%93410%2E)
11. Katharina Ehret and Benedikt Szmrecsanyi. 2016. An information-theoretic approach to assess linguistic complexity, pages 71–94. De Gruyter, Berlin, Boston. [find](https://scholar.google.com/scholar?q=Katharina+Ehret+and+Benedikt+Szmrecsanyi%2E+2016%2E+An+information%2Dtheoretic+approach+to+assess+linguistic+complexity%2C+pages+71%E2%80%9394%2E+De+Gruyter%2C+Berlin%2C+Boston%2E)
12. Marcelo Finger, Maria Clara Paixão De Sousa, Cristiane Namiuti, Vanessa Martins Do Monte, Aline Silva Costa, Felipe Ribas Serras, Mariana Lourenço Sturzeneker, Miguel De Mello Carpi, Mayara Feliciano Palma, and Gabriela Alves Lachi. 2025. Building Carolina: Metadata for Provenance and Typology in a… [find](https://scholar.google.com/scholar?q=Marcelo+Finger%2C+Maria+Clara+Paix%C3%A3o+De+Sousa%2C+Cristiane+Namiuti%2C+Vanessa+Martins+Do+Monte%2C+Aline+Silva+Costa%2C+Felipe+Ribas+Serras%2C+Mariana+Louren%C3%A7o+Sturzeneker%2C+Miguel+De+Mello+Carpi%2C+Mayara+Feliciano+)
13. Peter D. Grünwald and Paul M.B. Vitányi. 2008. Algorithmic information theory. In Pieter Adriaans and Johan van Benthem, editors, Philosophy of Information, Handbook of the Philosophy of Science, pages 281–317. North-Holland, Amsterdam. [find](https://scholar.google.com/scholar?q=Peter+D%2E+Gr%C3%BCnwald+and+Paul+M%2EB%2E+Vit%C3%A1nyi%2E+2008%2E+Algorithmic+information+theory%2E+In+Pieter+Adriaans+and+Johan+van+Benthem%2C+editors%2C+Philosophy+of+Information%2C+Handbook+of+the+Philosophy+of+Science%2C+page)
14. Carl J. Huberty and Stephen Olejnik. 2006. Applied MANOVA and Discriminant Analysis, 1st edition. Wiley Series in Probability and Statistics. Wiley. [find](https://scholar.google.com/scholar?q=Carl+J%2E+Huberty+and+Stephen+Olejnik%2E+2006%2E+Applied+MANOVA+and+Discriminant+Analysis%2C+1st+edition%2E+Wiley+Series+in+Probability+and+Statistics%2E+Wiley%2E)
15. Sidney Evaldo Leal and Sandra Maria Aluísio. 2024. Complexidade textual e suas tarefas relacionadas. In H. M. Caseli and M. G. V. Nunes, editors, Processamento de Linguagem Natural: Conceitos, Técnicas e Aplicações em Português, 3rd edition, book chapter 25. BPLN. [find](https://scholar.google.com/scholar?q=Sidney+Evaldo+Leal+and+Sandra+Maria+Alu%C3%ADsio%2E+2024%2E+Complexidade+textual+e+suas+tarefas+relacionadas%2E+In+H%2E+M%2E+Caseli+and+M%2E+G%2E+V%2E+Nunes%2C+editors%2C+Processamento+de+Linguagem+Natural%3A+Conceitos%2C+T%C3%A9cnica)
16. Sidney Evaldo Leal, Magali Sanches Duran, Carolina Evaristo Scarton, Nathan Siegle Hartmann, and Sandra Maria Aluísio. 2024. NILC-Metrix: Assessing the complexity of written and spoken language in Brazilian Portuguese. Language Resources and Evaluation, 58(1):73–110. [find](https://scholar.google.com/scholar?q=Sidney+Evaldo+Leal%2C+Magali+Sanches+Duran%2C+Carolina+Evaristo+Scarton%2C+Nathan+Siegle+Hartmann%2C+and+Sandra+Maria+Alu%C3%ADsio%2E+2024%2E+NILC%2DMetrix%3A+Assessing+the+complexity+of+written+and+spoken+language+in+Bra)
17. Danielle S. McNamara, Arthur C. Graesser, Philip M. McCarthy, and Zhiqiang Cai. 2014. Automated Evaluation of Text and Discourse with Coh-Metrix, 1st edition. Cambridge University Press. [find](https://scholar.google.com/scholar?q=Danielle+S%2E+McNamara%2C+Arthur+C%2E+Graesser%2C+Philip+M%2E+McCarthy%2C+and+Zhiqiang+Cai%2E+2014%2E+Automated+Evaluation+of+Text+and+Discourse+with+Coh%2DMetrix%2C+1st+edition%2E+Cambridge+University+Press%2E)
18. Felipe Serras, Miguel Carpi, Matheus Branco, and Marcelo Finger. 2024a. Analysing and validating language complexity metrics across South American indigenous languages. In Proceedings of the Workshop on Cognitive Modeling and Computational Linguistics, pages 152–165, Bangkok, Thailand. Association f… [find](https://scholar.google.com/scholar?q=Felipe+Serras%2C+Miguel+Carpi%2C+Matheus+Branco%2C+and+Marcelo+Finger%2E+2024a%2E+Analysing+and+validating+language+complexity+metrics+across+South+American+indigenous+languages%2E+In+Proceedings+of+the+Workshop+)
19. Felipe Ribas Serras, Miguel de Mello Carpi, Mariana Lourenço Sturzeneker, Mayara Feliciano Palma, Aline Silva Costa, Vanessa Martins do Monte, Cristiane Namiuti, Maria Clara Ramos Morales Crespo, Maria Clara Paixão de Sousa, and Marcelo Finger. 2026. Automatic analysis and classification of discours… [find](https://scholar.google.com/scholar?q=Felipe+Ribas+Serras%2C+Miguel+de+Mello+Carpi%2C+Mariana+Louren%C3%A7o+Sturzeneker%2C+Mayara+Feliciano+Palma%2C+Aline+Silva+Costa%2C+Vanessa+Martins+do+Monte%2C+Cristiane+Namiuti%2C+Maria+Clara+Ramos+Morales+Crespo%2C+Mari)
20. Felipe Ribas Serras, Mariana Sturzeneker, Miguel de Mello Carpi, Mayara Feliciano Palma, Maria Clara Ramos Morales Crespo, Aline Silva Costa, Vanessa Martins Do Monte, Cristiane Namiuti, Maria Clara Paixão de Souza, and Marcelo Finger. 2024b. Exploring computational discernibility of discourse domai… [find](https://scholar.google.com/scholar?q=Felipe+Ribas+Serras%2C+Mariana+Sturzeneker%2C+Miguel+de+Mello+Carpi%2C+Mayara+Feliciano+Palma%2C+Maria+Clara+Ramos+Morales+Crespo%2C+Aline+Silva+Costa%2C+Vanessa+Martins+Do+Monte%2C+Cristiane+Namiuti%2C+Maria+Clara+P)
21. Olena Shcherbakova, Volker Gast, Damián E. Blasi, Hedvig Skirgård, Russell D. Gray, and Simon J. Greenhill. 2023. A quantitative global test of the complexity trade-off hypothesis: the case of nominal and verbal grammatical marking. Linguistics Vanguard, 9(s1):155–167. [find](https://scholar.google.com/scholar?q=Olena+Shcherbakova%2C+Volker+Gast%2C+Dami%C3%A1n+E%2E+Blasi%2C+Hedvig+Skirg%C3%A5rd%2C+Russell+D%2E+Gray%2C+and+Simon+J%2E+Greenhill%2E+2023%2E+A+quantitative+global+test+of+the+complexity+trade%2Doff+hypothesis%3A+the+case+of+nominal)
22. Benedikt Szmrecsanyi. 2009. Typological parameters of intralingual variability: Grammatical analyticity versus syntheticity in varieties of english. Language Variation and Change, 21(3):319–353. [find](https://scholar.google.com/scholar?q=Benedikt+Szmrecsanyi%2E+2009%2E+Typological+parameters+of+intralingual+variability%3A+Grammatical+analyticity+versus+syntheticity+in+varieties+of+english%2E+Language+Variation+and+Change%2C+21%283%29%3A319%E2%80%93353%2E)