SIGMORPHON 2022 Shared Task on Morpheme Segmentation

Morphemes (prefixes, suffixes, root words) are linguistic descriptions, defined as the smallest meaningful unit of words. Our proposed shared task is morpheme segmentation that converts a text into a sequence of morphemes. In order to prepare a dataset for this task, we integrated all basic types of morphological databases (including UniMorph (Kirov et al., 2018b; McCarthy et al., 2020) – inflectional morphology; MorphyNet (Batsuren et al., 2021) – derivational morphology; Universal Dependencies (Nivre et al., 2017) and ten editions of Wiktionary – compound morphology and root words). In the future, we expect the NLP community will benefit a lot by innovating subword-based tokenization with this task. This shared task has two parts:

• Part 1: Word-level morpheme segmentation
• Part 2: Sentence-level morpheme segmentation

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Two subtasks will be scored separately. Participant teams may submit as many systems as they want to as many subtasks as they want.

Part 1: Word-level Morpheme Segmentation

At the word level, participants will be asked to segment a given word into a sequence of morphemes. Input words contains all types of word forms: root words, derived words, inflected words, and compound words.

Data

Training and development data are UTF-8-encoded tab-separated values files. Each example occupies a single line and consists of input word, the corresponding morpheme sequence, and the corresponding morphological category. The following shows three lines of English data:

inaccuracies in @@accurate @@cy @@s 110
dictionary dictionary 000
screwdriver screw @@drive @@er 011

Note: The third column as the morphological category is an optional feature that can only be used to oversample or undersample training data.

First example is a derived word with prefix (in-) and suffixes (-cy and -s), and second example is a root word. Third example is a compound word. In the test datasets, we will provide only first column of data as input words.

Languages

Development languages are:

1. ces: Czech
2. eng: English
3. fra: French
4. hun: Hungarian
5. spa: Spanish
6. ita: Italian
7. lat: Latin
8. rus: Russian

Surprise language is:

9. mon: Mongolian

Data Statistics

word class	English	Spanish	Hungarian	French	Italian	Russian	Czech	Latin	Mongolian
100	126544	502229	410662	105192	253455	221760	-	831991	7266
010	203102	18449	24923	67983	41092	72970	-	0	2201
101	13790	458	101189	478	317	1909	-	0	35
000	101938	15843	6952	13619	21037	2921	-	50338	1604
011	5381	82	1654	506	140	328	-	0	0
110	106570	346862	323119	126196	237104	481409	-	0	7855
001	16990	248	3320	1684	431	259	-	0	5
111	3059	343	54279	186	158	2658	-	0	0
total words	577374	884514	926098	382797	553734	784214	38682	882329	18966

Word category description

For some of the development languages, we are providing the word categories so that participant can deal with imbalanced situation of morphological categories.

word class	Description	English example (input ==> output)
100	Inflection only	played ==> play @@ed
010	Derivation only	player ==> play @@er
101	Inflection and Compound	wheelbands ==> wheel @@band @@s
000	Root words	progress ==> progress
011	Derivation and Compound	tankbuster ==> tank @@bust @@er
110	Inflection and Derivation	urbanizes ==> urban @@ize @@s
001	Compound only	hotpot ==> hot @@pot
111	Inflection, Derivation, Compound	trackworkers ==> track @@work @@er @@s

Baseline results

The following table shows the word-level task results of pretrained BertTokenizer on English. This pretrained model was employed from HuggingFace.

word class	inflection	derivation	compound	R	P	F1	lev. distance
001	no	no	yes	64.11	46.60	53.97	1.42
101	yes	no	yes	50.12	51.57	50.83	1.51
011	no	yes	yes	38.93	36.85	37.86	2.96
111	yes	yes	yes	28.30	34.81	31.22	3.22
010	no	yes	no	33.90	25.29	28.97	2.75
110	yes	yes	no	26.17	24.92	25.53	3.31
100	yes	no	no	19.14	12.16	14.87	2.73
000	no	no	no	5.55	2.02	2.96	2.11
total	-	-	-	28.79	20.99	24.28	2.69

Part 2: Sentence-level Morpheme Segmentation

At the sentence level, participating systems are expected to predict a sequence of morphemes for a given sentence. The following shows two lines of English data:

Six weeks of basic training . Six week @@s of base @@ic train @@ing .
Fistfights , please . Fist @@fight @@s , please .

The following shows two lines of Mongolian data:

Гэрт эмээ хоол хийв . Гэр @@т эмээ хоол хийх @@в .
Би өдөр эмээ уусан . Би өдөр эм @@ээ уух @@сан .

In above example, эмээ is a hononym of two different words, first means a grandmother and second is medicine. Depending on the context, the second homonym word is inflectional form of medicine and it is segmentable.

Languages

Development languages are:

1. ces: Czech
2. eng: English
3. mon: Mongolian

Data Statistics

	train	dev	test
Czech	1000	500	500
English	11007	1783	1845
Mongolian	1000	500	600

Baseline results

Language	Precison	Recall	F-measure	Lev. distance
Czech	36.76	30.35	33.25	21.01
English	63.68	65.77	64.71	5.50
Mongolian	20.00	29.95	23.99	28.86

Evaluation

We will provide python evaluation scripts, reporting the following evaluation measures:

• Precision - fraction of correctly predicted morphemes on all predicted morphemes
• Recall - ratio of correctly predicted morphemes on all gold morphemes
• F-measure - the harmonic mean of the precision and recall
• Edit distance - average Levenshtein distance between the predicted output and the gold instance.

Submission

Please submit your team's results to khuyagbaatar.b@gmail.com CCing your teammates by May 13th, 2022 (AoE). Each submission should be a .tar.gz or .zip file.

Timeline

Development Phase

• February 23, 2022: Training splits for development languages are released at https://github.com/sigmorphon/2022SegmentationST/tree/v0.2
• February 28, 2022: Development splits for development languages are released at https://github.com/sigmorphon/2022SegmentationST/tree/v0.2
• March 15, 2022: Evaluation tool of word-level task (English baseline results included) is released at https://github.com/sigmorphon/2022SegmentationST/tree/v0.2
• March 22, 2022: Evaluation tool of sentence-level task is released at /evaluation
• March 29, 2022: Full baseline results are released at /baseline

Generalization Phase

• April 8 April 18, 2022: Training and development splits for surprise languages released /data/surprise

Evaluation Phase

• April 15 April 29, 2022: Test splits for development and surprise languages are released at /data
• April 29 May 13, 2022: Participants' submissions due.

Write-up Phase

• May 13 May 27, 2022: Participants' draft system description papers due.
• May 20 June 3, 2022: Participants' camera-ready system description papers due.

Organizers

• Khuyagbaatar Batsuren (National University of Mongolia)
• Gábor Bella (University of Trento)
• Aryaman Arora (Georgetown University)
• Viktor Martinović (University of Vienna)
• Kyle Gorman (Graduate center, City University Of New York)
• Zdeněk Žabokrtský (Charles University)
• Amarsanaa Ganbold (National University of Mongolia)
• Šárka Dohnalová (Charles University)
• Magda Ševčíková (Charles University)
• Kateřina Pelegrinová (University of Ostrava)
• Fausto Giunchiglia (University of Trento)
• Ryan Cotterell (ETH Zürich)
• Ekaterina Vylomova (University of Melbourne)

License

The data is released under the Creative Commons Attribution-ShareAlike 3.0 Unported License inherited from Wiktionary itself.

References

Kirov, C., Cotterell, R., Sylak-Glassman, J., Walther, G., Vylomova, E., Xia, P., Faruqui, M., Mielke, S., McCarthy, A., Kübler, S., Yarowsky, D., Eisner, J., and Hulden, M. (2018). UniMorph 2.0: Universal Morphology. Proceedings of LREC 2018.

McCarthy, A.D., Kirov, C., Grella, M., Nidhi, A., Xia, P., Gorman, K., Vylomova, E., Mielke, S.J., Nicolai, G., Silfverberg, M. and Arkhangelskij, T., (2020). UniMorph 3.0: Universal Morphology.. Proceedings of LREC 2020.

Batsuren, K., Bella, G. and Giunchiglia, F., (2021). MorphyNet: a Large Multilingual Database of Derivational and Inflectional Morphology. In Proceedings of SIGMORPHON 2021 (pp. 39-48).

Nivre, J., Agić, Ž., Ahrenberg, L., Antonsen, L., Aranzabe, M.J., Asahara, M., Ateyah, L., Attia, M., Atutxa, A., Augustinus, L. and Badmaeva, E., (2017). Universal Dependencies 2.1.