---
title: "Introducing, evaluating ukWaC, a very large web-derived corpus"
description: "They describe ukWaC, built in 2007 within the WaCky project by crawling the .uk web domain. 17 references."
authors: ["Adriano Ferraresi", "Eros Zanchetta", "Marco Baroni", "Silvia Bernardini"]
year: 2008
venue: "Proceedings of the 4th Web as Corpus Workshop"
source: "https://aclanthology.org/2008.wac-1.8/"
licence: "CC BY-NC-SA 3.0 (ACL Anthology, before 2016)"
licence_url: "https://creativecommons.org/licenses/by-nc-sa/3.0/"
summary_licence: "Elamur Cosmic License"
canonical: "https://research.elamur.ai/free/en/papers/ferraresi-2008-introducing-evaluating-ukwac-very-large/"
---
[Elamur Research](https://md.research.elamur.ai/free/en/) · [this page in HTML](https://research.elamur.ai/free/en/papers/ferraresi-2008-introducing-evaluating-ukwac-very-large/)

[home](https://md.research.elamur.ai/free/en/) / [papers](https://md.research.elamur.ai/free/en/papers/) / [2008](https://md.research.elamur.ai/free/en/papers/2008/page/2/) / Introducing, evaluating ukWaC, a very large web-derived corpus of English

# Introducing, evaluating ukWaC, a very large web-derived corpus of English

**Authors:** [Adriano Ferraresi](https://md.research.elamur.ai/free/en/authors/adriano-ferraresi/), Eros Zanchetta, [Marco Baroni](https://md.research.elamur.ai/free/en/authors/marco-baroni/) and [Silvia Bernardini](https://md.research.elamur.ai/free/en/authors/silvia-bernardini/) · **Year:** 2008 · **Venue:** Proceedings of the 4th Web as Corpus Workshop · **Publisher:** [European Language Resources Association (ELRA)](https://md.research.elamur.ai/free/en/publishers/european-language-resources-association-elra/) · **Licence:** [CC BY-NC-SA 3.0 (ACL Anthology, before 2016)](https://creativecommons.org/licenses/by-nc-sa/3.0/)

**Links:** [Publisher's page](https://aclanthology.org/2008.wac-1.8/) · [PDF](https://aclanthology.org/2008.wac-1.8.pdf)

## Summary
The authors wanted a freely available English corpus that is much larger than traditional reference collections but still mixes genres and topics the way a balanced corpus does. They describe ukWaC, built in 2007 within the WaCky project by crawling the .uk web domain. Seed URLs came from Google queries made of random word pairs. The words were drawn from three vocabulary sources so that both formal and personal-interest pages would turn up. The crawled pages then passed through a cleaning pipeline:
- size and mime-type filters;
- removal of exact duplicates;
- a heuristic boilerplate stripper based on tag density;
- a filter based on the share of function words;
- removal of pornographic spam;
- detection of near-duplicates with shingling.

The result has more than 2 billion tokens, POS tags and lemmas. The authors evaluated what the corpus contains by comparing its vocabulary with the BNC. The resource matters because, at the time, it was among the largest English corpora of its kind and the only freely available, linguistically annotated English corpus taken from the web.

## Key points
- Seeds came from 1,000 word pairs of mid-frequency BNC content words, 500 pairs from the spoken BNC and 500 pairs from a learners' vocabulary list. Each query returned at most 10 URLs, and only one URL was kept per domain.
- The crawl used Heritrix, was restricted to .uk and ran for 10 days. Only text/html documents between 5 and 200KB were kept, and every document with an exact duplicate was dropped, including all of its copies.
- The boilerplate stripper keeps the text span that maximises the number of tokens minus the number of tags. On the CLEANEVAL text-only task it scored 85.41 on average, while the best competitor scored 84.07.
- The connected-text filter used 151 function words. A page needed at least 10 types and 30 tokens, and at least a quarter of its words had to be function words. Near-duplicates were found by comparing 25 randomly chosen 5-grams per document, after function words had been removed.
- The corpus is distributed in a format ready for the IMS Open Corpus Workbench (CWB) and is also available through the Sketch Engine. The authors later parsed it with a dependency parser.

## Interesting ideas
- The genre balance of a crawl can be steered by where the seed words come from: words from newspapers and reference corpora bring public-sphere texts, while basic everyday vocabulary brings blogs and forums.
- Boilerplate can be found without supervision by picking the stretch of a page where text is dense and markup is sparse. This cheap heuristic beat the supervised competitors in its evaluation.
- A minimum share of function words is a single test that rejects lists and catalogues, keeps real connected prose and also works as a rough language identifier.
- When data is plentiful, prefer precision over recall. Drop every copy of an exact duplicate, and detect near-duplicates only after cleaning, so that shared boilerplate does not cause false matches.
- Judge a new corpus by comparing its vocabulary with an established reference corpus, so that differences in topic and register become visible.

## For Mova

How these ideas could serve Mova, our small open language model — its files, stages and tests:

- **I1** (learn): when collecting raw English for silver parsing, draw query or selection words from several vocabulary sources, so the silver data covers both formal prose and casual narrative.
- **I2** (tokens): add a tag-density cleaner in front of the tokenizer, so navigation menus and disclaimers never become sentences that the tagger and parser have to handle.
- **I3** (learn): run this test before sending text to the witness parsers, so that agreement among them is not inflated by easy fragments that are not real sentences.
- **I4** (learn): deduplicate silver and teacher-labelled sentences with shingles on cleaned text, which also lowers the risk of evaluation items leaking into training data.
- **I5** (learn): compare the vocabulary of the silver data with the vocabulary of the UD treebanks, to find domains where the parsers are likely to be weak and need negative controls.

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

📚 Shelves (2): [🖥️ Computer Science](https://md.research.elamur.ai/free/en/shelves/computer-science/) · 18,614 works · [🤖 Artificial Intelligence](https://md.research.elamur.ai/free/en/shelves/computer-science/artificial-intelligence/) · 17,965 works

🧭 Topics (2): [English](https://md.research.elamur.ai/free/en/topics/english/) · 2,379 works · [📏 Evaluation & benchmarks](https://md.research.elamur.ai/free/en/topics/evaluation-benchmarks/) · 1,341 works

## Cite

Cite as: Adriano Ferraresi, Eros Zanchetta, Marco Baroni and Silvia Bernardini. 2008. Introducing, evaluating ukWaC, a very large web-derived corpus of English. Proceedings of the 4th Web as Corpus Workshop.

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

```bibtex
@inproceedings{ferraresi2008introducing,
  title = {{Introducing, evaluating ukWaC, a very large web-derived corpus of English}},
  author = {Adriano Ferraresi, Eros Zanchetta, Marco Baroni and Silvia Bernardini},
  booktitle = {Proceedings of the 4th Web as Corpus Workshop},
  year = {2008},
  url = {https://aclanthology.org/2008.wac-1.8/}
}
```

- [← previous Exploiting Lexical Resources for Disambiguating CJK and Arabic Orthographic Variants](https://md.research.elamur.ai/free/en/papers/halpern-2008-exploiting-lexical-resources-disambiguating-cjk/)
- [next → Iʿrāb, Tanwīn and Status Constructus: Some Thoughts on the History of the Nominal Declension in Semitic and Arabic](https://md.research.elamur.ai/free/en/papers/stempel-2026-irab-tanwin-status-constructus-some/)
- [↑ back to papers of 2008](https://md.research.elamur.ai/free/en/papers/2008/page/2/)

## References

17 references, 1 of them with a card of ours. ↗ leads to the work, «find» searches for one we have no id for yet.

1. A. Baayen. 2001. Word frequency distributions. Kluwer, Dordrecht. [find](https://scholar.google.com/scholar?q=A%2E+Baayen%2E+2001%2E+Word+frequency+distributions%2E+Kluwer%2C+Dordrecht%2E)
2. M. Baroni and S. Bernardini, editors. 2006. Wacky! Working papers on the Web as Corpus, Bologna. Gedit. [http://corpus.leeds.ac.uk/internet.html](http://corpus.leeds.ac.uk/internet.html) [↗](http://corpus.leeds.ac.uk/internet.html)
3. M. Baroni, S. Bernardini, A. Ferraresi, and E. Zanchetta. 2008. The WaCky Wide Web: A Collection of Very Large Linguistically Processed Web-Crawled Corpora. submitted. [find](https://scholar.google.com/scholar?q=M%2E+Baroni%2C+S%2E+Bernardini%2C+A%2E+Ferraresi%2C+and+E%2E+Zanchetta%2E+2008%2E+The+WaCky+Wide+Web%3A+A+Collection+of+Very+Large+Linguistically+Processed+Web%2DCrawled+Corpora%2E+submitted%2E)
4. D. Biber, S. Johansson, G. Leech, S. Conrad, and E. Finegan. 1999. Longman grammar of spoken and written English. Harlow, London. [find](https://scholar.google.com/scholar?q=D%2E+Biber%2C+S%2E+Johansson%2C+G%2E+Leech%2C+S%2E+Conrad%2C+and+E%2E+Finegan%2E+1999%2E+Longman+grammar+of+spoken+and+written+English%2E+Harlow%2C+London%2E)
5. A. Broder, S. Glassman, M. Manasse, and G. Zweig. 1997. Syntactic clustering of the web. In Proceedings of the Sixth International World Wide Web Conference, pages 391–404, Santa Clara, California. [find](https://scholar.google.com/scholar?q=A%2E+Broder%2C+S%2E+Glassman%2C+M%2E+Manasse%2C+and+G%2E+Zweig%2E+1997%2E+Syntactic+clustering+of+the+web%2E+In+Proceedings+of+the+Sixth+International+World+Wide+Web+Conference%2C+pages+391%E2%80%93404%2C+Santa+Clara%2C+California%2E)
6. C. Fairon, H. Naets, A. Kilgarriff, and G.-M. de Schryver, editors. 2007. Building and exploring web corpora – Proceedings of the 3rd Web as Corpus Workshop, incorporating Cleaneval. Presses Universitaires de Louvain, Louvain. [find](https://scholar.google.com/scholar?q=C%2E+Fairon%2C+H%2E+Naets%2C+A%2E+Kilgarriff%2C+and+G%2E%2DM%2E+de+Schryver%2C+editors%2E+2007%2E+Building+and+exploring+web+corpora+%E2%80%93+Proceedings+of+the+3rd+Web+as+Corpus+Workshop%2C+incorporating+Cleaneval%2E+Presses+Universit)
7. A. Ferraresi. 2007. Building a very large corpus of English obtained by web crawling: ukWaC. Master’s thesis, University of Bologna. Retrieved January 28, 2008 from [http://wacky.sslmit.unibo.it](http://wacky.sslmit.unibo.it). [↗](http://wacky.sslmit.unibo.it)
8. W. Fletcher. 2004. Making the web more useful as a source for linguistic corpora. In U. Connor and T. Upton, editors, Corpus Linguistics in North America 2002, Amsterdam. Rodopi. [find](https://scholar.google.com/scholar?q=W%2E+Fletcher%2E+2004%2E+Making+the+web+more+useful+as+a+source+for+linguistic+corpora%2E+In+U%2E+Connor+and+T%2E+Upton%2C+editors%2C+Corpus+Linguistics+in+North+America+2002%2C+Amsterdam%2E+Rodopi%2E)
9. M. Hundt, N. Nesselhauf, and C. Biewer, editors. 2007. Corpus linguistics and the web. Rodopi, Amsterdam. [find](https://scholar.google.com/scholar?q=M%2E+Hundt%2C+N%2E+Nesselhauf%2C+and+C%2E+Biewer%2C+editors%2E+2007%2E+Corpus+linguistics+and+the+web%2E+Rodopi%2C+Amsterdam%2E)
10. A. Kilgarriff and G. Grefenstette. 2003. [Introduction to the special issue on the web as corpus](https://md.research.elamur.ai/free/en/papers/kilgarriff-2003-introduction-special-issue-web-as/). Computational Linguistics, 29(3):333–347.
11. D. Lee. 2001. Genres, registers, text types, domains, and styles: Clarifying the concepts and navigating a path through the BNC jungle. Language Learning & Technology, 5(3):37–72. [find](https://scholar.google.com/scholar?q=D%2E+Lee%2E+2001%2E+Genres%2C+registers%2C+text+types%2C+domains%2C+and+styles%3A+Clarifying+the+concepts+and+navigating+a+path+through+the+BNC+jungle%2E+Language+Learning+%26+Technology%2C+5%283%29%3A37%E2%80%9372%2E)
12. P. Rayson and R. Garside. 2000. Comparing corpora using frequency profiling. In Proceedings of Workshop on Comparing Corpora of ACL 2000, pages 1–6, Hong Kong, China. [find](https://scholar.google.com/scholar?q=P%2E+Rayson+and+R%2E+Garside%2E+2000%2E+Comparing+corpora+using+frequency+profiling%2E+In+Proceedings+of+Workshop+on+Comparing+Corpora+of+ACL+2000%2C+pages+1%E2%80%936%2C+Hong+Kong%2C+China%2E)
13. M. Santini and S. Sharoff, editors. 2007. Proceedings of the CL 2007 Colloquium: Towards a Reference Corpus of Web Genres, Birmingham, UK. [find](https://scholar.google.com/scholar?q=M%2E+Santini+and+S%2E+Sharoff%2C+editors%2E+2007%2E+Proceedings+of+the+CL+2007+Colloquium%3A+Towards+a+Reference+Corpus+of+Web+Genres%2C+Birmingham%2C+UK%2E)
14. M. Santini. 2007. Characterizing genres of web pages: genre hybridism and individualization. In Proceedings of the 40th Hawaii International Conference on System Sciences, poster session, pages 1–10, Waikoloa, Hawaii. [find](https://scholar.google.com/scholar?q=M%2E+Santini%2E+2007%2E+Characterizing+genres+of+web+pages%3A+genre+hybridism+and+individualization%2E+In+Proceedings+of+the+40th+Hawaii+International+Conference+on+System+Sciences%2C+poster+session%2C+pages+1%E2%80%9310%2C+)
15. S. Sharoff. 2006. Creating general-purpose corpora using automated search engine queries. In M. Baroni and S. Bernardini, editors, Wacky! Working papers on the Web as Corpus, pages 63–98, Bologna. Gedit. [find](https://scholar.google.com/scholar?q=S%2E+Sharoff%2E+2006%2E+Creating+general%2Dpurpose+corpora+using+automated+search+engine+queries%2E+In+M%2E+Baroni+and+S%2E+Bernardini%2C+editors%2C+Wacky%21+Working+papers+on+the+Web+as+Corpus%2C+pages+63%E2%80%9398%2C+Bologna%2E+Ged)
16. M. Thelwall. 2005. Creating and using web corpora. International Journal of Corpus Linguistics, 10(4):517–541. [find](https://scholar.google.com/scholar?q=M%2E+Thelwall%2E+2005%2E+Creating+and+using+web+corpora%2E+International+Journal+of+Corpus+Linguistics%2C+10%284%29%3A517%E2%80%93541%2E)
17. M. Ueyama. 2006. Evaluation of japanese web-based reference corpora: Effects of seed selection and time interval. In M. Baroni and S. Bernardini, editors, Wacky! Working papers on the Web as Corpus, pages 99–126, Bologna. Gedit. [find](https://scholar.google.com/scholar?q=M%2E+Ueyama%2E+2006%2E+Evaluation+of+japanese+web%2Dbased+reference+corpora%3A+Effects+of+seed+selection+and+time+interval%2E+In+M%2E+Baroni+and+S%2E+Bernardini%2C+editors%2C+Wacky%21+Working+papers+on+the+Web+as+Corpus%2C+p)

*Updated 2 November 2026*