LX-Tokenizer's documentation
LX-Tokenizer
LX-Tokenizer is a freely available online service for tokenizing Portuguese text. It was developed and is mantained by the NLX-Natural Language and Speech Group at the University of Lisbon, Department of Informatics.
You may also be interested to use our LX Sentence Splitter, LX-Tagger, or LX-Suite online services for delimiting sentences, part-of-speech tagging and sub-syntactic analysis of Portuguese.
Features and evaluation
The LX-Tokenizer service is composed by two processing tools:
- LX Sentence Splitter:
Marks sentence boundaries with<s>…</s>, and paragraph boundaries with<p>…</p>.
Unwraps sentences split over different lines.A f-score of 99.94% was obtained when testing on a 12,000 sentence corpus accurately hand tagged with respect to sentence and paragraph boundaries.
- LX-Tokenizer:
- Segments text into lexically relevant tokens, using
whitespace as the separator. Note that, in these examples,
the
|(vertical bar) symbol is used to mark the token boundaries more clearly. um exemplo → |um|exemplo|- Expands contractions. Note that the first element of an
expanded contraction is marked with an
_(underscore) symbol: do → |de_|o|- Marks spacing around punctuation or symbols. The
\*and the*/symbols indicate a space to the left and a space to the right, respectively: um, dois e três → |um|,*/|dois|e|três|5.3 → |5|.|3|1. 2 → |1|.*/|2|8 . 6 → |8|\*.*/|6|- Detaches clitic pronouns from the verb. The detached pronoun
is marked with a
-(hyphen) symbol. When in mesoclisis, a-CL-mark is used to signal the original position of the detached clitic. Additionally, possible vocalic alterations of the verb form are marked with a#(hash) symbol: dá-se-lho → |dá|-se|-lhe_|-o|afirmar-se-ia → |afirmar-CL-ia|-se|vê-las → |vê#|-las|- This tool also handles ambiguous strings. These are words that, depending on their particular occurrence, can be tokenized in different ways. For instance:
deste → |deste|when occurring as a Verbdeste → |de|este|when occurring as a contraction (Preposition + Demonstrative)
This tool achieves a f-score of 99.72%.
- Segments text into lexically relevant tokens, using
whitespace as the separator. Note that, in these examples,
the
These tools work in a pipeline scheme, where each tool takes as input the output of the previous tool.
Authorship
LX-Tokenizer was developed by António Branco and João Silva at the NLX—Natural Language and Speech Group at the University of Lisbon, Department of Informatics.
Acknowledgments
The development of a state-of-the-art, complete suite of shallow processing tools for Portuguese was supported by FCT-Fundação para a Ciência e Tecnologia under the contract POSI/PLP/47058/2002 for the project TagShare and the contract POSI/PLP/61490/2004 for the project QueXting, and the European Commission under the contract FP6/STREP/27391 for the project LT4eL.
Publications
Irrespective of the most recent version of this tool you may use, when mentioning it, please cite this reference:
- Silva, João, António Branco, Sérgio Castro and Ruben Reis, 2010, "Out-of-the-Box Robust Parsing of Portuguese". In Proceedings of the 9th International Conference on the Computational Processing of Portuguese (PROPOR2010), Lecture Notes in Artificial Intelligence, 6001, Berlin, Springer, pp. 75–85.
Contact us
Contact us using the following email address: 'nlxgroup' concatenated with 'at' concatenated with 'di.fc.ul.pt'.
Why LX-Tokenizer?
LX because LX is the "code" name Lisboners like to use to refer to their hometown.