Introduction of the Asian Language Treebank
Hammam Riza, Michael Purwoadi, Gunarso, Teduh Uliniansyah
Badan Pengkajian dan Penerapan Teknologi, Indonesia

Luong Chi Mai, †Vu Tat Thang, ‡Nguyen Phuong Thái†

Institute of Information Technology, Vietnam
University of Engineering of Technology, Vietnam†

Aw Ai Ti, Sharifah Mahani Aljunied

Institute for Infocomm Research, Singapore

Rapid Sun, Vichet Chea

National Institute of Posts, Telecoms and ICT, Cambodia‡

Khin Mar Soe, Khin Thandar Nwet

University of Computer Studies, Yangon, Myanmar

Masao Utiyama, Chenchen Ding

National Institute of Information and Communication Technology, Japan

Abstract—This paper introduces our project for developing
Asian Language Treebank (ALT). The ALT project aims to advance the state-of-the-art Asian natural language processing(NLP) techniques through the open collaboration for developing
and using ALT. The project is a joint effort of six institutes formaking a parallel treebank for seven languages: English, Indonesian, Japanese, Khmer, Malay, Myanmar, and Vietnamese. The
process of building ALT began with sampling about 20,000 sentences from English Wikinews, and then these sentences weretranslated into the other six languages. ALT will have word segmentation, part-of-speech tags, syntactic analysis annotations,
together with word alignment links among these languages.
Keywords— Asian languages; parallel corpus; treebank

I. INTRODUCTION

Natural language processing (NLP) needs raw and annotated resources for research and development. Especially, thepresent state-of-the-art NLP techniques rely on treebanks, i.e.,
linguistically annotated corpora of natural language texts. The
basic linguistic annotations in treebanks include word segmentation, part-of-speech (POS) tags, and syntactic information.
The annotated data are used to produce NLP tools, such as
word segmenters, POS taggers, and syntactic parsers. Those
NLP tools are necessary to NLP applications, such as machinetranslation (MT), Web search engines, and summarization.
Almost all NLP researches and tools are based on treebanks ina broad sense.

The main problem in creating a treebank is that it needs
high-level linguistic competency for the language of interest.
As a result, existing treebanks are limited in their sizes, annotation types, and languages. In particular, no publicly available
POS tagged and syntactically annotated corpus is available formost of the Asian languages.
This background has motivated us to launch a project forbuilding Asian Language Treebank (ALT). The purpose of the
ALT project is to advance the state-of-the-art Asian NLP technologies through the open collaboration for developing andusing ALT. At the initial stage of developing ALT, seven languages are targeted: English, Indonesian, Japanese, Khmer,
Malay, Myanmar (Burmese), and Vietnamese. One of the characteristics of ALT is that it uses parallel sentences for creating
treebanks. English sentences were first sampled from Wikinews, and then translated into the other six languages. Finally,
the sentences in each language are linguistically annotated.
Word alignment links between different languages are also
provided using English as the pivot language.
Our approach is unique that no other treebank for Asian
languages has this property. It has both scientific and engineering benefits. For the scientific benefits, we can compare various NLP techniques as applied to various languages on thesame ground, which will reveal how NLP techniques can beapplicable to different languages. For the engineering benefits,
we can easily transfer the NLP techniques available in resourcerich languages (for example, English and Japanese) into otherlanguages, which will advance Asian NLP.
The structure of this paper is as follows. First, we survey
Asian NLP resources for the six languages other than English.
The purpose of this survey is two-fold: it provides the overview
of current Asian NLP resources, so that one can readily accessthem, and it highlights the contributions of ALT to the community. Then, we describe the details of ALT. Finally, we
discuss the future of ALT, especially the availability of ALT to
the NLP community.
II. SURVEY OF ASIAN NLP RESOURCES

ALT is a parallel treebank, which has word segmentation,
POS tags, and syntax annotations with word alignment links.
Hence, we mainly focus on NLP resources and tools related tothese annotations. We are also aware of the importance of parallel corpora in developing NLP tools and applications, especially machine translation. Therefore, parallel corpora are alsomentioned. For example, the 3rd Workshop on Asian Translation focuses on machine translation among Asian languages

and makes use of Chinese, English, Hindi, Indonesian, Japanese and Korean parallel texts [1].
A. Indonesian NLP resources
Indonesia has a long history on computational linguistics
research. In 1987-1994, BPPT has been involved in CICCJapan Project for Multilingual Machine Translation System(MMTS) based on inter-lingual approach. This project has animportant role in the research and development of Indonesiancomputational linguistics. Many basic resources and tools were
produced, such as Indonesian Basic Dictionary that containmorphological, syntactic, and semantic information (24,000
word roots), Indonesian Gazetteer, Indonesian Monolingual
Corpus (1 million words), Indonesian Analysis System, etc.
and those resources has become a foundation for other projects.
Furthermore, Indonesia have also involved in the UNL project
started in 1997.

Indonesia has joined PAN localization in 2010-2012
through the collaboration of BPPT and University of Indonesia
with Pakistan, China, Nepal, Sri Lanka, Laos, Cambodia, Bhutan and Thailand. Indonesia also joined international researchcollaboration with A-STAR, U-STAR Consortium, Asian
WordNet, ASEAN MT, and others. These projects have makeuse of the early Bahasa Indonesian resources, which resulted inother resources and improving existing resources. Up to now,
BPPT has collected around 10 million sentences of Indonesianmonolingual corpus, 250 thousand sentences of EnglishIndonesian parallel corpus, and enhanced the Indonesian Electronic Dictionary. Indonesian POS Tagger and Corpus Management System are also created to support various projects.
Two leading universities in Indonesia, Indonesian University and Bandung Institute of Technology, have also been very
active in the field of computational linguistics. Many resources
and tools have been developed such as statistical POS tagger,
Indonesian WordNet, Indonesian POS Tagged Corpus, Indonesian Named Entity Tagged Corpus, Indonesian Syntactical Tree
Tagged Corpus, Indonesian Dependency Tree Tagged Corpus,
Indonesian-English Parallel Corpus and Indonesian-Japanese
Parallel Corpus. Other universities have begun to be involvedin this field such as Gadjah Mada University, Syarif Hidayatullah State Islamic University, Telkom University, Surabaya Institute of Technology, Electronics Engineering Polytechnic
Institute of Surabaya, Trisakti University, Bina Nusantara University, Gunadarma University, Indonesia University of Education Petra University, etc. which has been organized into the
new Indonesian Association of Computational Linguistics(INACL).

B. Japanese NLP resources
Japanese is one of the languages without spaces between
words. Consequently, word segmentation is the first step forthe most of NLP applications. Note that POS tagging is usuallyconducted together with word segmentation, because these areclosely related and jointly determined in Japanese. Then, dependency analysis is often performed, while phrase structure
analysis is considered as another option.
One of the well-known treebanks in Japanese is Kyoto
University Text Corpus [2], which is “a text corpus that is

manually annotated with various linguistic information. It consists of approximately 40,000 sentences from Mainichi newspaper in 1995 with morphological and syntactic annotations.
Out of these sentences, 5,000 sentences are annotated withpredicate-argument structures including zero anaphora andco-references.” However, “note that this package does not include original sentences but include only annotation information. To recover the complete annotated corpus, it is necessary to obtain the Mainichi 1995 CD-ROM.” Consequently, it
is not easy to use this corpus outside Japan. Based on this corpus, JUMAN, a morphological analyzer, and KNP, a dependency, case structure, and anaphora analyzer, have been developed and made available to the public [3].
Other word segmentation or morphological analysis tools
are ChaSen, MeCab and KyTea [4]. As stated above, in Japanese, the word segmentation and POS tagging is tightly coupled. Consequently, the above tools conduct both analyses
simultaneously. However, because their models are trained onother corpora that are not available to the public, it is hard tocompare a new method or tool with them in the same setting.

Besides KNP, CaboCha [5] and J.DepP [6] also conduct
Japanese dependency analysis. Note that CaboCha is used with
MeCab to conduct Japanese morphological and dependency
analyses, while J.DepP alone carries out both analyses. J.DepP
can be trained on the freely-available Kyoto-University and
NTT Blog Corpus [7], comprising about 4,000 sentences. Another parser is Ckylark [8], a latent-annotated probabilistic context-free grammar parser.
A manually annotated word alignment data is available as“Kyoto Free Translation Task Japanese-English Alignment
Data” [9]. This corpus is a derivative of “Japanese-English
Bilingual Corpus of Wikipedia's Kyoto Articles” [10], which isalso a derivative of Japanese Wikipedia. Because the copyrightof Wikipedia is Creative Commons Attribution-Share-Alike
3.0 License, the translation of Japanese Wikipedia articles into
English and the word alignment between Japanese and English
are also available under that license. This is an example where
the license can foster the development of NLP resources.

C. Khmer NLP resources
As an Asian Language, Cambodian language, which is referred to as Khmer, is also written continuously without using
spaces between words. Thus, Khmer word segmenter is themost important tool for Khmer NLP. The recent paper about
Khmer Word Segmention [13] demonstrated the highest accuracy up to 0.99 of F-score. The tool was trained with around97,000 of manually annotated sentences. The corpus was collected from various domains. This corpus is currently not open
to the public.
Because Khmer language is a low resource language in
NLP, collecting and making data is time consuming. Public
POS tagged data is only found at PAN localization’s website[14]. The corpus is about 3,000 manually annotated sentences,which were used to train for POS tagger for Khmer language.
The tool is published by PAN localization [15].
Currently, NIPTICT has been manually annotating POS
tagged data about 30,000 sentences, which is segmented byKhmer Word Segmenter [13]. The data is not open to the public.
Other useful textual resources are government documents
such as law and declaration. Most documents are officiallywritten in three languages, Khmer, English, and French, in parallel. These files are open to the public as PDF format only,
and can be found freely on the government websites (for example, the constitution of the kingdom of Cambodia [16]).
These are confidential documents to share as editable format.
So, it is another time consuming task for converting them into
text format. It needs good OCR and human corrections.
D. Malay NLP resources
Bahasa Malaysia is a language spoken mostly by the Malay
people in Peninsular Malaysia, Brunei, Singapore and otherareas in Southeast Asia. The language is considered as low
resource for both NLP and MT tasks as there are not many
annotated data or bilingual texts available. As a result, mostworks on Malay language processing is linguistically and/or
heuristically driven.

One of the earliest works on Malay language processing
was Othman’s Stemming Algorithm [17] for information retrieval, which has 121 rules for prefixes, suffixes and infixes.
Muhamad [18] further improved the work by Fatimah [19]using Rule Frequency Order with 426 rules and a root word
dictionary. Similarly most Part-of-Speech tagging for Malay
language was predicted based on the word morphology. The
first Malay tagger developed by Mohamed [20] combined ahidden Markov model with morphological information to identify the POS of unknown words in the Malay language. Juhaida[21] further improved the POS tagging for unknown words
using Decision Tree and Nearest Neighbor. However, the data
used for the training algorithm was not mentioned
A Malay corpus database was created under Malaysia’s
Language and Literature Agency (DBP) for the storage andretrieval of large texts. Chuah [22] reported that the databasehas over 71,444,326 words over different sub-domains and isaugmented with Malay Text Analysis system. Aw [23] developed a rule-based system that performs morphological analysis
and syntactic parsing on the Malay text and use the linguistic
information from the parsing trees to reorder the word, transfer
the syntactic structure and generate the final English text. Vu[24] used morphological information of both Malay and English language to extract bilingual terms from Malay-English
comparable corpora.

E. Myanmar NLP resources
Myanmar language does not use spaces between words.
Therefore, word segmentation of Myanmar sentences is needed.
The current Myanmar word segmenter achieves a precision of
97.9% [25]. The segmenter uses the annotated corpus containing 60,000 sentences currently. This corpus is not available tothe public.
Myanmar POS tagging and parsing are also required for
NLP tasks such as machine translation, name entity recognition
and text summarization. Myanmar POS tagging and parsing arestill under research at NLP Lab, University of Computer Study,
Yangon.

Since Myanmar language is still low-resource for NLP
tasks, the very first work for NLP tasks is creating the corpus.
NLP Lab has created a corpus of 20,000 sentences (travel domain) in order to implement “the Network based ASEAN Languages Translation Public Service” (www.aseanmt.org) collaborating with the ASEAN countries. The lab has also prepared
Myanmar part in ALT collaborating with NICT [12].
Myanmar-English-Myanmar bilingual Dictionary has beendeveloped to obtain a structurally similar WordNet for Myanmar language. The dictionary consists of 30,000 words currently [26].

F. Vietnamese NLP resources
Like many other Asian languages such as Chinese, Japanese and Thai, there is no word delimiter in Vietnamese. The
space is a syllable delimiter but not a word delimiter, so a Vietnamese sentence can often be segmented in many ways. Second, Vietnamese is an isolating language in which words do
not change their forms according to their grammatical function
in a sentence. Third, the Vietnamese syntax conforms to thesubject verb-object (SVO) word order.

Vietnamese treebank (VTB) [27] is a branch of a national
project which aims to develop basic resources and tools for
Vietnamese Language and Speech Processing (VLSP) [28]. In
addition to treebank, the VLSP project also develops other textprocessing resources and tools including a Vietnamese machine readable dictionary, an English-Vietnamese parallel corpus, a word segmenter, a POS tagger, a chunker, and a syntactic parser. The Vietnamese treebank (VTB) and other resources
and tools developed by the VLSP project have been posted on
the VLSP web page [29] since 2010. The main goal was tobuild a corpus of 70,000 word segmented sentences, 20,000
POS tagged sentences, and 10,000 syntactic trees. As a resource, raw texts from the news domain focusing on social andpolitical topics were extracted. VTB construction is an iterative
process involving three phases: annotation, guideline revision,and tool upgrade. Annotators were supported by automaticlabeling tools, which are based on statistical machine learning
methods, for sentence pre-processing. A tree editor is developed to support manual annotation. As a result, an annotationagreement of around 90% was achieved.
For word segmentation, vnTokenizer - a highly accuratesegmenter (over 95%) which uses a hybrid approach to automatically tokenize Vietnamese text is used. This approachcombines a finite-state automata technique, regular expression
parsing, and a maximal-matching strategy augmented by statistical methods that resolve ambiguities of segmentation [30].
Also JVnTagger - a POS tagger based on Conditional Random
Fields and Maximum Entropy is developed. The training data
size is 10,000 sentences. Experiments with 5-fold cross validation showed that F1 scores for CRFs and Maxent were 90.40%
and 91.03%, respectively [28]. Another tool used was a syntactic parser based on lexicalized probabilistic context-freeGrammars (LPCFGs). Bikel's parser was also customized
which is well designed and easy to adapt to new languages. An
entropy-based method is investigated for detecting errors andinconsistencies in the word-segmented and POS-tagged partsof VTB data.

Vietnam team joined international research collaboration
with A-STAR, U-STAR Consortium, ASEAN MT, and others
III. PROPOSAL OF ASIAN LANGUAGE TREE BANK (ALT)A. Overview of ALT
The ALT project was initiated by the National Institute ofInformation and Communications Technology, Japan (NICT)
in 2014. NICT started to build Japanese and English ALT andworked with the University of Computer Studies, Yangon,
Myanmar (UCSY) to build Myanmar ALT in 2014. Then, theBadan Pengkajian dan Penerapan Teknologi, Indonesia (BPPT),the Institute for Infocomm Research, Singapore (I2R), the Institute of Information Technology, Vietnam (IOIT), and the National Institute of Posts, Telecoms and ICT, Cambodia(NIPTICT) joined to make ALT for Indonesian, Malay, Vietnamese, and Khmer in 2015 [11].

The data are represented in an XML format. Thus, the server is flexible enough to accept different POS tags for different
languages, for example. It is also possible to mix automatic andmanual annotations. That is, at first, automatic analysis is conducted by NLP tools. Then, it can be manually corrected using
the server.

This server also supports users, groups and task management and has a multilingual help system. The administrator canassign particular tasks to users considering their linguistic expertise (such as assigning only translation tasks etc.). If the user
is assigned all tasks he/she can continuously and efficiently
work through all processes for the given sentence. For wordalignment, POS tagging and syntax annotation, user input canbe performed using only the mouse. Fig. 1 shows the user interface for word alignment annotation between an English sentence and the corresponding translated Myanmar sentence, andFig. 2 shows the user interface for syntax annotation, or constituency tree building [12].

ALT comprises about 20,000 sentences originally sampledfrom the English Wikinews in 2014. These were already translated into the other six languages. These will be annotated withword segmentation, POS tags, and syntax information, in addition to the word alignment information. An example of parallel
sentences of English, Indonesian, Japanese, Khmer, Malay,
Myanmar, and Vietnamese is shown below.

[EN] Italy have defeated Portugal 31-5 in Pool C of the 2007
Rugby World Cup at Parc des Princes, Paris, France.
[ID] Italia berhasil mengalahkan Portugal 31-5 di grup C dalam
Piala Dunia Rugby 2007 di Parc des Princes, Paris, Perancis.
[JA] フランスのパリ、パルク・デ・プランスで行われた2007 年ラグビーワールドカップのプール C で、イタリア
は 31 対 5 でポルトガルを下した。
[KH] អុី លី នឈះេលព័រទុយ ល់ 31-5
កងប៉ូ លCៃនពីធី បកួ ត នរ ន់ពិភពេ កៃនកី
ល់ឱប
ំ2007ែដល ប ពឹតេ៉ សេឌស បីន កង ៉ រសងំ ។[MS] Itali telah mengalahkan Portugal 31-5 dalam Pool C pada
Piala Dunia Ragbi 2007 di Parc des Princes, Paris, Perancis.
[MY] ြပင်သစ် င်ိ င ံ ပါရီ မိ ပါ့ဒက်စ် ပရင်စ့ က် ၌ ၂၀၀၇ခ စ် ရပ်ဘီ

Fig. 1.

Word alignment interface

Fig. 2.

Tree building interfaceကမာ့ ဖလား တွင ် အီတလီ သည် ေပ တဂီ ကိ ၃၁-၅ ဂိး ြဖင့်
ေရကးကန် စီ တွင ် ံးနိမသ့် ာွ းပါသည် ။[VI] Ý đã đánh bại Bồ Đào Nha với tỉ số 31-5 ở Bảng C Giải vôđịch Rugby thế giới 2007 tại Parc des Princes, Pari, Pháp.

It is easily understood that development of ALT needs international collaboration of NLP researchers, because ALT
needs high level of linguistic expertise for each language.
B. ALT annotation Web server
NICT has built an annotation server for developing ALT. It
has been used to build Myanmar and Japanese ALT. The annotation server helps all steps of the development; translation,
word segmentation, word alignment, POS tagging, and syntax
annotation.

C. Current progress
The translation of the English sentences into the six languages has been completed. In addition to the six languages,
the English sentences have also been translated into additional
three languages, Laos, Thai, and Philippine. However, we currently have no institute to annotate them with linguistic information for ALT of these three languages.

Myanmar parts of ALT has been constructed within a year[12]. We will use it for Myanmar NLP. We are checking andimproving the Myanmar data. The construction of Japaneseand English ALT are ongoing. The construction of other ALT
has begun in 2015.
IV. DISCUSSION AND CONCLUSION

We make ALT to support the advancement of Asian NLP.
In order to reach this goal, the license of ALT is very important.
We selected English Wikinews as the original texts, because its license is Creative Commons Attribution 2.5 License.
This is a very open license under which we can use it evencommercially, provided that we give appropriate credit. This is
in contrast with many treebanks whose original texts havestricter copyrights.

We are now discussing on the licensing of ALT. The license should help us promote the open collaboration for developing and using ALT to the community.

This paper has discussed the ALT project being conductedby the six institutes. ALT is intended to accelerate NLP development in low resource Asian languages. The corpus comprises about 20,000 sentences from the news domain consisting of
Asian language translations from a shared English source text
annotated with word segmentation, word alignment, POS tags,
and syntax trees. ALT includes English, Indonesian, Japanese,
Khmer, Malay, Myanmar and Vietnamese in the short term,and extend to other languages in the long term through collaboration with international research organizations.
ACKNOWLEDGMENT

This work is partly supported by the ASEAN IVO Project“Open Collaboration for Developing and Using Asian Language Treebank”.
[1]

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