File size: 49,296 Bytes
6fa4bc9
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
{
    "paper_id": "F13-2010",
    "header": {
        "generated_with": "S2ORC 1.0.0",
        "date_generated": "2023-01-19T09:41:45.278558Z"
    },
    "title": "N-gram Language Models and POS Distribution for the Identification of Spanish Varieties",
    "authors": [
        {
            "first": "Marcos",
            "middle": [],
            "last": "Zampieri",
            "suffix": "",
            "affiliation": {
                "laboratory": "",
                "institution": "University of Cologne",
                "location": {
                    "country": "Germany"
                }
            },
            "email": ""
        },
        {
            "first": "Binyam",
            "middle": [],
            "last": "Gebrekidan Gebre",
            "suffix": "",
            "affiliation": {},
            "email": ""
        },
        {
            "first": "Sascha",
            "middle": [],
            "last": "Diwersy",
            "suffix": "",
            "affiliation": {
                "laboratory": "",
                "institution": "University of Cologne",
                "location": {
                    "country": "Germany"
                }
            },
            "email": ""
        }
    ],
    "year": "",
    "venue": null,
    "identifiers": {},
    "abstract": "Ngrammes et Traits Morphosyntaxiques pour la Identification de Vari\u00e9t\u00e9s de l'Espagnol Notre article pr\u00e9sente exp\u00e9rimentations portant sur la classification supervis\u00e9e de vari\u00e9t\u00e9s nationales de l'espagnol. Outre les approches classiques, bas\u00e9es sur l'utilisation de ngrammes de caract\u00e8res ou de mots, nous avons test\u00e9 des mod\u00e8les calcul\u00e9s selon des traits morphosyntaxiques, l'objectif \u00e9tant de v\u00e9rifier dans quelle mesure il est possible de parvenir \u00e0 une classification automatique des vari\u00e9t\u00e9s d'une langue en s'appuyant uniquement sur des descripteurs grammaticaux. Les calculs ont \u00e9t\u00e9 effectu\u00e9s sur la base d'un corpus de textes journalistiques de quatre pays hispanophones (Espagne, Argentine, Mexique et P\u00e9rou).",
    "pdf_parse": {
        "paper_id": "F13-2010",
        "_pdf_hash": "",
        "abstract": [
            {
                "text": "Ngrammes et Traits Morphosyntaxiques pour la Identification de Vari\u00e9t\u00e9s de l'Espagnol Notre article pr\u00e9sente exp\u00e9rimentations portant sur la classification supervis\u00e9e de vari\u00e9t\u00e9s nationales de l'espagnol. Outre les approches classiques, bas\u00e9es sur l'utilisation de ngrammes de caract\u00e8res ou de mots, nous avons test\u00e9 des mod\u00e8les calcul\u00e9s selon des traits morphosyntaxiques, l'objectif \u00e9tant de v\u00e9rifier dans quelle mesure il est possible de parvenir \u00e0 une classification automatique des vari\u00e9t\u00e9s d'une langue en s'appuyant uniquement sur des descripteurs grammaticaux. Les calculs ont \u00e9t\u00e9 effectu\u00e9s sur la base d'un corpus de textes journalistiques de quatre pays hispanophones (Espagne, Argentine, Mexique et P\u00e9rou).",
                "cite_spans": [],
                "ref_spans": [],
                "eq_spans": [],
                "section": "Abstract",
                "sec_num": null
            }
        ],
        "body_text": [
            {
                "text": "Spanish is a world language with official status in 21 countries. It is regarded to be a Pluricentric language with a number of interacting centres and language varieties (Thompson, 1992) . Each of these national varieties has their own characteristics in terms of phonetics, lexicon and syntax.",
                "cite_spans": [
                    {
                        "start": 171,
                        "end": 187,
                        "text": "(Thompson, 1992)",
                        "ref_id": "BIBREF11"
                    }
                ],
                "ref_spans": [],
                "eq_spans": [],
                "section": "Introduction",
                "sec_num": "1"
            },
            {
                "text": "Computational applications can benefit from identifying the correct variety of Spanish texts when undertaking tasks such as Machine Translation or Information Extraction, as they are able to handle lexical, orthographic and syntactic variation more accurately. The task is modelled as a classification problem with very similar methods to those applied to general purpose language identification (Dunning, 1994) .",
                "cite_spans": [
                    {
                        "start": 396,
                        "end": 411,
                        "text": "(Dunning, 1994)",
                        "ref_id": "BIBREF2"
                    }
                ],
                "ref_spans": [],
                "eq_spans": [],
                "section": "Introduction",
                "sec_num": "1"
            },
            {
                "text": "To the best of our knowledge, very few attempts have been made to address the problem of identifying language varieties as evidenced in 2.1. In this work we try to classify texts retrieved from newspapers published in 2008 from four different Spanish speaking countries : Spain, Argentina, Mexico and Peru. Moreover, we propose the use of new features, not limited to the classical word and character n-grams. We experimented features based on POS distribution and morphosyntactic information. The use of knowledge-rich features is not an attempt to outperform word and character n-gram-based methods, but an attempt to examine the extent to which these varieties differ in terms of grammar.",
                "cite_spans": [],
                "ref_spans": [],
                "eq_spans": [],
                "section": "Introduction",
                "sec_num": "1"
            },
            {
                "text": "Language identification is the task of automatically identifying the language contained in a given document. State-of-the-art methods apply n-gram language models at the character and sometimes word-level with results usually above 95% accuracy. This level of success is very common when dealing with languages which are typologically not closely related. This is however not the case of language varieties in which the distinction is based on very subtle differences that algorithms can be trained to recognize.",
                "cite_spans": [],
                "ref_spans": [],
                "eq_spans": [],
                "section": "Related Work",
                "sec_num": "2"
            },
            {
                "text": "One of the first general purpose language identification approaches was the work of Ingle (1980) . Ingle applied Zipf's law distribution to order the frequency of stop words in a text and used this information for language identification. Dunning (1994) introduced the use of character n-grams and statistics for language identification. In this study, the likelihood of ngrams was calculated using Markov models and this was used as the most informative feature for identification. Other studies applying n-gram language models for language identification include Cavnar and Trenkle (1994) implemented as TextCat 1 , Grefenstette (1995) , and Vojtek and Belikova (2007) .",
                "cite_spans": [
                    {
                        "start": 84,
                        "end": 96,
                        "text": "Ingle (1980)",
                        "ref_id": "BIBREF5"
                    },
                    {
                        "start": 239,
                        "end": 253,
                        "text": "Dunning (1994)",
                        "ref_id": "BIBREF2"
                    },
                    {
                        "start": 565,
                        "end": 590,
                        "text": "Cavnar and Trenkle (1994)",
                        "ref_id": "BIBREF0"
                    },
                    {
                        "start": 614,
                        "end": 615,
                        "text": "1",
                        "ref_id": null
                    },
                    {
                        "start": 618,
                        "end": 637,
                        "text": "Grefenstette (1995)",
                        "ref_id": "BIBREF3"
                    },
                    {
                        "start": 644,
                        "end": 670,
                        "text": "Vojtek and Belikova (2007)",
                        "ref_id": "BIBREF13"
                    }
                ],
                "ref_spans": [],
                "eq_spans": [],
                "section": "Related Work",
                "sec_num": "2"
            },
            {
                "text": "In the recent years, a number of language identification methods were developed for internet data such as Martins and Silva (2005) and Rehurek and Kolkus (2009) . The most recent general purpose language identification method to our knowledge is the one published by Lui and Baldwin (2012) . Their software, called langid.py, has language models for 97 languages, using various data sources. The method achieved results of up to 94.7% accuracy, thus outperforming similar tools. All models described in this section neglect language varieties. Pluricentric languages, such as the case of Spanish, are represented by a unique class.",
                "cite_spans": [
                    {
                        "start": 106,
                        "end": 130,
                        "text": "Martins and Silva (2005)",
                        "ref_id": "BIBREF8"
                    },
                    {
                        "start": 135,
                        "end": 160,
                        "text": "Rehurek and Kolkus (2009)",
                        "ref_id": "BIBREF10"
                    },
                    {
                        "start": 267,
                        "end": 289,
                        "text": "Lui and Baldwin (2012)",
                        "ref_id": "BIBREF7"
                    }
                ],
                "ref_spans": [],
                "eq_spans": [],
                "section": "Related Work",
                "sec_num": "2"
            },
            {
                "text": "The identification of closely related languages is one of the bottlenecks of most n-gram-based models and there are only a few studies published about it. Ljube\u0161i\u0107 et al. (2007) propose a computational model for the identification of Croatian texts in comparison to other South Slavic languages reporting 99% recall and precision in three processing stages. One of these processing stages, includes a so-called black list, a list of forbidden words that appear only in 1. http ://odur.let.rug.nl/vannoord/TextCat/ Croatian texts, making the algorithm perform better.",
                "cite_spans": [
                    {
                        "start": 155,
                        "end": 177,
                        "text": "Ljube\u0161i\u0107 et al. (2007)",
                        "ref_id": "BIBREF6"
                    }
                ],
                "ref_spans": [],
                "eq_spans": [],
                "section": "Models for Similar Languages, Varieties and Dialects",
                "sec_num": "2.1"
            },
            {
                "text": "Ranaivo-Malancon (2006) presents a semi-supervised character-based model to distinguish between Indonesian and Malay, two closely related languages from the Austronesian family and Huang and Lee (2008) proposes a bag-of-words approach to distinguish Chinese texts from Mainland and Taiwan reporting results of up to 92% accuracy. More recently, Trieschnigg et al. Trieschnigg et al. (2012) described classification experiments for a set of sixteen Dutch dialects using the Dutch Folktale Database.",
                "cite_spans": [
                    {
                        "start": 181,
                        "end": 201,
                        "text": "Huang and Lee (2008)",
                        "ref_id": "BIBREF4"
                    },
                    {
                        "start": 345,
                        "end": 389,
                        "text": "Trieschnigg et al. Trieschnigg et al. (2012)",
                        "ref_id": "BIBREF12"
                    }
                ],
                "ref_spans": [],
                "eq_spans": [],
                "section": "Models for Similar Languages, Varieties and Dialects",
                "sec_num": "2.1"
            },
            {
                "text": "For romance languages, the DEFT2010 2 shared task aimed to classify French journalistic texts not only with respect to their geographical location but also incorporating a temporal dimension. For Portuguese, Zampieri and Gebre (2012) proposed a log-likelihood estimation method to distinguish between European and Brazilian Portuguese texts with results above 99.5% for character n-grams. The model was later applied to a multilingual setting with French and Spanish texts .",
                "cite_spans": [],
                "ref_spans": [],
                "eq_spans": [],
                "section": "Models for Similar Languages, Varieties and Dialects",
                "sec_num": "2.1"
            },
            {
                "text": "We collected four comparable corpora to use in our experiments, one for each language variety. To collect comparable samples, we retrieved texts published in the same year from local newspapers regarded to have similar register, as follows : Each sub-corpus contains a set of 1,000 documents randomly sampled to avoid bias towards a given topic or genre. These sub-corpora were divided in training and test settings of 500 documents each. Following the compilation of the corpora, four groups of features were selected. The list of features used and the aspect of language that these features aim to analyse are presented next :",
                "cite_spans": [],
                "ref_spans": [],
                "eq_spans": [],
                "section": "Methods",
                "sec_num": "3"
            },
            {
                "text": "-Character n-grams (2 to 5) : orthography and lexicon -Word uni-grams : lexicon -Word bi-grams : lexicon and syntax -POS and morphological features : morphology and syntax",
                "cite_spans": [],
                "ref_spans": [],
                "eq_spans": [],
                "section": "Methods",
                "sec_num": "3"
            },
            {
                "text": "The first three groups of features (knowledge-poor features) are standard in language identification and they were widely used in previous approaches. The fourth group of features (knowledge-rich features) is to our knowledge new and it consists of the use of POS and morphological feature annotation. The POS tags and morphological information were used as one unit in form of a compound tags (e.g. N-msc-sg or V-inf).",
                "cite_spans": [],
                "ref_spans": [],
                "eq_spans": [],
                "section": "Methods",
                "sec_num": "3"
            },
            {
                "text": "A snapshot of the tagset with nouns, adjectives and verbs is presented in table 2. The classification method is based on n-gram language models and document log-likelihood estimation (Dunning, 1993) as described in . Its performance is comparable to state-of-the-art methods in language identification which focus on similar languages. It was tested on Bosnian, Croatian and Serbian documents 3 achieving 91.0% accuracy. Models described in Ljube\u0161i\u0107 et al. (2007) achieved 90.3% and 95.7% accuracy using the same dataset.",
                "cite_spans": [
                    {
                        "start": 183,
                        "end": 198,
                        "text": "(Dunning, 1993)",
                        "ref_id": "BIBREF1"
                    },
                    {
                        "start": 441,
                        "end": 463,
                        "text": "Ljube\u0161i\u0107 et al. (2007)",
                        "ref_id": "BIBREF6"
                    }
                ],
                "ref_spans": [],
                "eq_spans": [],
                "section": "Methods",
                "sec_num": "3"
            },
            {
                "text": "The method calculates language models using Laplace probability distribution for smoothing and after this calculation computes the probability of each document to belong to a certain class using a log-likelihood function as shown in equation 1.",
                "cite_spans": [],
                "ref_spans": [],
                "eq_spans": [],
                "section": "Methods",
                "sec_num": "3"
            },
            {
                "text": "EQUATION",
                "cite_spans": [],
                "ref_spans": [],
                "eq_spans": [
                    {
                        "start": 0,
                        "end": 8,
                        "text": "EQUATION",
                        "ref_id": "EQREF",
                        "raw_str": "P(L|tex t) = arg max L N i=1 log P(n i |L) + log P(L)",
                        "eq_num": "(1)"
                    }
                ],
                "section": "Methods",
                "sec_num": "3"
            },
            {
                "text": "N is the number of n-grams in the test text, n i is the ith n-gram and L stands for the language models. Given a test text, we calculate the probability for each of the language models. The language model with higher probability determines the identified language of the text.",
                "cite_spans": [],
                "ref_spans": [],
                "eq_spans": [],
                "section": "Methods",
                "sec_num": "3"
            },
            {
                "text": "The first experiments used knowledge-poor features to classify the four Spanish varieties evaluated using precision (P), recall (R) and f-measure (F). Results ranged from 0.813 fmeasure for character 4-grams to 0.876 f-measure for word bi-grams. The results for each class remained constant for all features and this can be seen in table 3.",
                "cite_spans": [],
                "ref_spans": [],
                "eq_spans": [],
                "section": "Results",
                "sec_num": "4"
            },
            {
                "text": "3. http ://www.nljubesic.net/resources/tools/bs-hr-sr-language-identifier/ Feature P R F C 2-grams 0.835 0.804 0.819 C 3-grams 0.848 0.806 0.826 C 4-grams 0.842 0.787 0.813 C 5-grams 0.854 0.811 0.832 W 1-grams 0.879 0.848 0.848 W 2-grams 0.880 0.870 0.876",
                "cite_spans": [],
                "ref_spans": [],
                "eq_spans": [],
                "section": "Results",
                "sec_num": "4"
            },
            {
                "text": "The Peninsular Spanish class seemed to be the most difficult for the algorithm to identify in this setting. As an example, table 4 presents a confusion matrix for the character 4-grams feature in which the algorithm obtained its worst performance. The best results were obtained for the classification of texts from Argentina and Mexico reaching 0.999 average accuracy. As the confusion matrix in 4 indicated, the worst setting was again Spain x Argentina with an average result of 0.842 accuracy. All the results obtained were substantially higher than the 4-class classification setting. As classification algorithms tend to perform better in binary settings, this was an expected outcome.",
                "cite_spans": [],
                "ref_spans": [],
                "eq_spans": [],
                "section": "TABLE 3 -4-Class Classification",
                "sec_num": null
            },
            {
                "text": "Next we present the results obtained using POS distribution and morphological features, combined in sets of 2, 3 and 4 compound tags as explained in section 3. The classification between Mexican and Spanish texts obtained the best results reaching 0.831 using combinations of two tags. These two varieties also obtained satisfactory scores for character and The poorest results were obtained once again in the classification of Spanish and Argentinian texts, which also obtained the worst performance using knowledge-poor features. Even though the results are lower than those obtained using knowledge-poor features, the algorithm scored better than the expected 0.50 baseline, indicating that it is able to identify patterns in the datasets using only sets of morphosyntactical information. Named entities which usually help algorithms to identify varieties at the lexical level are not present in the experiments using POS tags and therefore do not influence the performance of the classifier.",
                "cite_spans": [],
                "ref_spans": [],
                "eq_spans": [],
                "section": "POS and Morphology",
                "sec_num": "4.1"
            },
            {
                "text": "To evaluate the relationship between the features explored here, we analysed results using hierarchical clustering. For each cluster, two p-values (between 0 and 1) are calculated via multiscale bootstrap resampling. These values indicate how strong the cluster is supported by data. The two p-values are : the AU (Approximately Unbiased), in red, computed by multiscale bootstrap resampling and BP (Bootstrap Probability) in green, computed by normal bootstrap resampling. The graphic shows the difference between the performance of knowledge-poor and knowledge-rich features, arranging each in a different cluster 1.",
                "cite_spans": [],
                "ref_spans": [],
                "eq_spans": [],
                "section": "Relationship Between Features",
                "sec_num": "4.2"
            },
            {
                "text": "The analysis grouped the two word-based feature groups in the same cluster, as they performed on average better than the character-based methods. Another interesting point of the analysis is that the results of character 4-and 5-grams are grouped in the same cluster due to an increase in performance when a larger amount of characters are taken into account. Character 4-and 5-grams features are closer to the lexical level taking whole words into account, which suggests that the model is more effective when using complete lexical items as features.",
                "cite_spans": [],
                "ref_spans": [],
                "eq_spans": [],
                "section": "FIGURE 1 -Cluster Dendogram with AU/BP Values",
                "sec_num": null
            },
            {
                "text": "As stated before, the morphological features were not expected to outperform the knowledgepoor models, but to be used to investigate differences in grammar. An interesting outcome of these experiments is the direct relationship between the algorithm's performance using knowledge-poor and knowledge-rich features. One clear example is the classification of Argentina and Spain which obtained the worst results with characters and words as well as when using POS and morphology : 0.843 and 0.666 accuracy respectively. Another example is Argentina and Mexico which achieved the best results using characters and words, 0.999 accuracy and the second best results with POS tags, 0.801 accuracy.",
                "cite_spans": [],
                "ref_spans": [],
                "eq_spans": [],
                "section": "FIGURE 1 -Cluster Dendogram with AU/BP Values",
                "sec_num": null
            },
            {
                "text": "For these reasons, the results presented here are an encouraging perspective for further studies. It is possible to use the outcome of the classification as a source of information for contrastive linguistics to provide quantitative overview on how these varieties converge and diverge in terms of grammar and lexicon. Linguistic analysis may be carried out using the most informative features in classification.",
                "cite_spans": [],
                "ref_spans": [],
                "eq_spans": [],
                "section": "FIGURE 1 -Cluster Dendogram with AU/BP Values",
                "sec_num": null
            },
            {
                "text": "We presented a first attempt to identify a set of four Spanish varieties in written texts with f-measure results ranging from 0.813 to 0.876. As expected, the binary classification settings have achieved significantly better results in comparison to the 4-class classification setting. The algorithm was able to distinguish between texts from Argentina and Mexico with an average accuracy of 0.999. As previously discussed, the integration of these language models in real-world NLP applications, should improve results in a number of NLP tasks.",
                "cite_spans": [],
                "ref_spans": [],
                "eq_spans": [],
                "section": "Conclusion and Future Perspectives",
                "sec_num": "5"
            },
            {
                "text": "The experiments used not only the classical character and word n-gram models but also morphosyntactic information combined with POS. This is to our knowledge a new contribution of our work to this kind of experiments. The classification with knowledge-rich features achieved up to 0.831 accuracy for Mexican and Peninsular Spanish. We observed a direct relationship between the performance of knowledge-poor and knowledge-rich features, binary settings which obtained good performance using characters and words also present good results using morphosyntactic information. This aspect should be better explored in future work through a careful linguistic analysis.",
                "cite_spans": [],
                "ref_spans": [],
                "eq_spans": [],
                "section": "Conclusion and Future Perspectives",
                "sec_num": "5"
            },
            {
                "text": "As future perspectives, first we wish to compare the performance of our method with general purpose language identification methods such as langid.py (Lui and Baldwin, 2012) . Second, we are replicating our experiments to a set of French varieties. Finally, we would like to experiment the combination of POS and word n-grams to investigate if performance increases.",
                "cite_spans": [
                    {
                        "start": 150,
                        "end": 173,
                        "text": "(Lui and Baldwin, 2012)",
                        "ref_id": "BIBREF7"
                    }
                ],
                "ref_spans": [],
                "eq_spans": [],
                "section": "Conclusion and Future Perspectives",
                "sec_num": "5"
            },
            {
                "text": "c ATALA",
                "cite_spans": [],
                "ref_spans": [],
                "eq_spans": [],
                "section": "",
                "sec_num": null
            }
        ],
        "back_matter": [
            {
                "text": "We would like to thank the anonymous reviewers for their careful feedback. TALN-R\u00c9CITAL 2013, 17-21 Juin, Les Sables d'Olonne ",
                "cite_spans": [],
                "ref_spans": [],
                "eq_spans": [],
                "section": "Acknowledgements",
                "sec_num": null
            }
        ],
        "bib_entries": {
            "BIBREF0": {
                "ref_id": "b0",
                "title": "N-gram-based text catogorization",
                "authors": [
                    {
                        "first": "W",
                        "middle": [],
                        "last": "Cavnar",
                        "suffix": ""
                    },
                    {
                        "first": "J",
                        "middle": [],
                        "last": "Trenkle",
                        "suffix": ""
                    }
                ],
                "year": 1994,
                "venue": "",
                "volume": "",
                "issue": "",
                "pages": "",
                "other_ids": {},
                "num": null,
                "urls": [],
                "raw_text": "Cavnar, W. and Trenkle, J. (1994). N-gram-based text catogorization. 3rd Symposium on Document Analysis and Information Retrieval (SDAIR-94).",
                "links": null
            },
            "BIBREF1": {
                "ref_id": "b1",
                "title": "Accurate methods for the statistics of surprise and coincidence",
                "authors": [
                    {
                        "first": "T",
                        "middle": [],
                        "last": "Dunning",
                        "suffix": ""
                    }
                ],
                "year": 1993,
                "venue": "Computational Linguistics -Special Issue on Using Large Corpora",
                "volume": "19",
                "issue": "1",
                "pages": "",
                "other_ids": {},
                "num": null,
                "urls": [],
                "raw_text": "Dunning, T. (1993). Accurate methods for the statistics of surprise and coincidence. Compu- tational Linguistics -Special Issue on Using Large Corpora, 19(1).",
                "links": null
            },
            "BIBREF2": {
                "ref_id": "b2",
                "title": "Statistical identification of language",
                "authors": [
                    {
                        "first": "T",
                        "middle": [],
                        "last": "Dunning",
                        "suffix": ""
                    }
                ],
                "year": 1994,
                "venue": "",
                "volume": "",
                "issue": "",
                "pages": "",
                "other_ids": {},
                "num": null,
                "urls": [],
                "raw_text": "Dunning, T. (1994). Statistical identification of language. Technical report, Computing Research Lab -New Mexico State University.",
                "links": null
            },
            "BIBREF3": {
                "ref_id": "b3",
                "title": "Comparing two language identification schemes",
                "authors": [
                    {
                        "first": "G",
                        "middle": [],
                        "last": "Grefenstette",
                        "suffix": ""
                    }
                ],
                "year": 1995,
                "venue": "Proceedings of JADT 1995, 3rd International Conference on Statistical Analysis of Textual Data",
                "volume": "",
                "issue": "",
                "pages": "",
                "other_ids": {},
                "num": null,
                "urls": [],
                "raw_text": "Grefenstette, G. (1995). Comparing two language identification schemes. In Proceedings of JADT 1995, 3rd International Conference on Statistical Analysis of Textual Data, Rome.",
                "links": null
            },
            "BIBREF4": {
                "ref_id": "b4",
                "title": "Contrastive approach towards text source classification based on top-bag-of-word similarity",
                "authors": [
                    {
                        "first": "C",
                        "middle": [],
                        "last": "Huang",
                        "suffix": ""
                    },
                    {
                        "first": "L",
                        "middle": [],
                        "last": "Lee",
                        "suffix": ""
                    }
                ],
                "year": 2008,
                "venue": "Proceedings of PACLIC 2008",
                "volume": "",
                "issue": "",
                "pages": "404--410",
                "other_ids": {},
                "num": null,
                "urls": [],
                "raw_text": "Huang, C. and Lee, L. (2008). Contrastive approach towards text source classification based on top-bag-of-word similarity. In Proceedings of PACLIC 2008, pages 404-410.",
                "links": null
            },
            "BIBREF5": {
                "ref_id": "b5",
                "title": "A Language Identification Table",
                "authors": [
                    {
                        "first": "N",
                        "middle": [],
                        "last": "Ingle",
                        "suffix": ""
                    }
                ],
                "year": 1980,
                "venue": "",
                "volume": "",
                "issue": "",
                "pages": "",
                "other_ids": {},
                "num": null,
                "urls": [],
                "raw_text": "Ingle, N. (1980). A Language Identification Table. Technical Translation International.",
                "links": null
            },
            "BIBREF6": {
                "ref_id": "b6",
                "title": "Language identification : How to distinguish similar languages ?",
                "authors": [
                    {
                        "first": "N",
                        "middle": [],
                        "last": "Ljube\u0161i\u0107",
                        "suffix": ""
                    },
                    {
                        "first": "N",
                        "middle": [],
                        "last": "Mikelic",
                        "suffix": ""
                    },
                    {
                        "first": "D",
                        "middle": [],
                        "last": "Boras",
                        "suffix": ""
                    }
                ],
                "year": 2007,
                "venue": "Proceedings of the 29th International Conference on Information Technology Interfaces",
                "volume": "",
                "issue": "",
                "pages": "",
                "other_ids": {},
                "num": null,
                "urls": [],
                "raw_text": "Ljube\u0161i\u0107, N., Mikelic, N., and Boras, D. (2007). Language identification : How to distinguish similar languages ? In Proceedings of the 29th International Conference on Information Technology Interfaces.",
                "links": null
            },
            "BIBREF7": {
                "ref_id": "b7",
                "title": "langid.py : An off-the-shelf language identification tool",
                "authors": [
                    {
                        "first": "M",
                        "middle": [],
                        "last": "Lui",
                        "suffix": ""
                    },
                    {
                        "first": "T",
                        "middle": [],
                        "last": "Baldwin",
                        "suffix": ""
                    }
                ],
                "year": 2012,
                "venue": "Proceedings of the 50th Meeting of the ACL",
                "volume": "",
                "issue": "",
                "pages": "",
                "other_ids": {},
                "num": null,
                "urls": [],
                "raw_text": "Lui, M. and Baldwin, T. (2012). langid.py : An off-the-shelf language identification tool. In Proceedings of the 50th Meeting of the ACL.",
                "links": null
            },
            "BIBREF8": {
                "ref_id": "b8",
                "title": "Language identification in web pages",
                "authors": [
                    {
                        "first": "B",
                        "middle": [],
                        "last": "Martins",
                        "suffix": ""
                    },
                    {
                        "first": "M",
                        "middle": [],
                        "last": "Silva",
                        "suffix": ""
                    }
                ],
                "year": 2005,
                "venue": "Proceedings of the 20th ACM Symposium on Applied Computing (SAC)",
                "volume": "",
                "issue": "",
                "pages": "763--768",
                "other_ids": {},
                "num": null,
                "urls": [],
                "raw_text": "Martins, B. and Silva, M. (2005). Language identification in web pages. Proceedings of the 20th ACM Symposium on Applied Computing (SAC), Document Engineering Track. Santa Fe, EUA., pages 763-768.",
                "links": null
            },
            "BIBREF9": {
                "ref_id": "b9",
                "title": "Automatic identification of close languages -case study : Malay and indonesian",
                "authors": [
                    {
                        "first": "B",
                        "middle": [],
                        "last": "Ranaivo-Malancon",
                        "suffix": ""
                    }
                ],
                "year": 2006,
                "venue": "ECTI Transactions on Computer and Information Technology",
                "volume": "2",
                "issue": "",
                "pages": "126--134",
                "other_ids": {},
                "num": null,
                "urls": [],
                "raw_text": "Ranaivo-Malancon, B. (2006). Automatic identification of close languages -case study : Malay and indonesian. ECTI Transactions on Computer and Information Technology, 2 :126- 134.",
                "links": null
            },
            "BIBREF10": {
                "ref_id": "b10",
                "title": "Language identification on the web : Extending the dictionary method",
                "authors": [
                    {
                        "first": "R",
                        "middle": [],
                        "last": "Rehurek",
                        "suffix": ""
                    },
                    {
                        "first": "M",
                        "middle": [],
                        "last": "Kolkus",
                        "suffix": ""
                    }
                ],
                "year": 2009,
                "venue": "Proceedings of CICLing. Lecture Notes in Computer Science",
                "volume": "",
                "issue": "",
                "pages": "357--368",
                "other_ids": {},
                "num": null,
                "urls": [],
                "raw_text": "Rehurek, R. and Kolkus, M. (2009). Language identification on the web : Extending the dictionary method. In Proceedings of CICLing. Lecture Notes in Computer Science, pages 357-368. Springer.",
                "links": null
            },
            "BIBREF11": {
                "ref_id": "b11",
                "title": "Spanish as a pluricentric language",
                "authors": [
                    {
                        "first": "R",
                        "middle": [],
                        "last": "Thompson",
                        "suffix": ""
                    }
                ],
                "year": 1992,
                "venue": "Pluricentric Languages : Different Norms in Different Nations",
                "volume": "",
                "issue": "",
                "pages": "45--70",
                "other_ids": {},
                "num": null,
                "urls": [],
                "raw_text": "Thompson, R. (1992). Spanish as a pluricentric language. In Clyne, M., editor, Pluricentric Languages : Different Norms in Different Nations, pages 45-70. CRC Press.",
                "links": null
            },
            "BIBREF12": {
                "ref_id": "b12",
                "title": "An exploration of language identification techniques for the dutch folktale database",
                "authors": [
                    {
                        "first": "D",
                        "middle": [],
                        "last": "Trieschnigg",
                        "suffix": ""
                    },
                    {
                        "first": "D",
                        "middle": [],
                        "last": "Hiemstra",
                        "suffix": ""
                    },
                    {
                        "first": "M",
                        "middle": [],
                        "last": "Theune",
                        "suffix": ""
                    },
                    {
                        "first": "F",
                        "middle": [],
                        "last": "De Jong",
                        "suffix": ""
                    },
                    {
                        "first": "T",
                        "middle": [],
                        "last": "Meder",
                        "suffix": ""
                    }
                ],
                "year": 2012,
                "venue": "Proceedings of LREC2012",
                "volume": "",
                "issue": "",
                "pages": "",
                "other_ids": {},
                "num": null,
                "urls": [],
                "raw_text": "Trieschnigg, D., Hiemstra, D., Theune, M., de Jong, F., and Meder, T. (2012). An exploration of language identification techniques for the dutch folktale database. In Proceedings of LREC2012.",
                "links": null
            },
            "BIBREF13": {
                "ref_id": "b13",
                "title": "Comparing language identification methods based on markov processess",
                "authors": [
                    {
                        "first": "P",
                        "middle": [],
                        "last": "Vojtek",
                        "suffix": ""
                    },
                    {
                        "first": "M",
                        "middle": [],
                        "last": "Belikova",
                        "suffix": ""
                    }
                ],
                "year": 2007,
                "venue": "Slovko, International Seminar on Computer Treatment of Slavic and East European Languages",
                "volume": "",
                "issue": "",
                "pages": "",
                "other_ids": {},
                "num": null,
                "urls": [],
                "raw_text": "Vojtek, P. and Belikova, M. (2007). Comparing language identification methods based on markov processess. In Slovko, International Seminar on Computer Treatment of Slavic and East European Languages.",
                "links": null
            },
            "BIBREF14": {
                "ref_id": "b14",
                "title": "Automatic identification of language varieties : The case of Portuguese",
                "authors": [
                    {
                        "first": "M",
                        "middle": [],
                        "last": "Zampieri",
                        "suffix": ""
                    },
                    {
                        "first": "B",
                        "middle": [
                            "G"
                        ],
                        "last": "Gebre",
                        "suffix": ""
                    }
                ],
                "year": 2012,
                "venue": "Proceedings of KONVENS2012",
                "volume": "",
                "issue": "",
                "pages": "233--237",
                "other_ids": {},
                "num": null,
                "urls": [],
                "raw_text": "Zampieri, M. and Gebre, B. G. (2012). Automatic identification of language varieties : The case of Portuguese. In Proceedings of KONVENS2012, pages 233-237, Vienna, Austria.",
                "links": null
            },
            "BIBREF15": {
                "ref_id": "b15",
                "title": "Classifying pluricentric languages : Extending the monolingual model",
                "authors": [
                    {
                        "first": "M",
                        "middle": [],
                        "last": "Zampieri",
                        "suffix": ""
                    },
                    {
                        "first": "B",
                        "middle": [
                            "G"
                        ],
                        "last": "Gebre",
                        "suffix": ""
                    },
                    {
                        "first": "S",
                        "middle": [],
                        "last": "Diwersy",
                        "suffix": ""
                    }
                ],
                "year": 2012,
                "venue": "Proceedings of the Fourth Swedish Language Technlogy Conference (SLTC2012)",
                "volume": "",
                "issue": "",
                "pages": "79--80",
                "other_ids": {},
                "num": null,
                "urls": [],
                "raw_text": "Zampieri, M., Gebre, B. G., and Diwersy, S. (2012). Classifying pluricentric languages : Extending the monolingual model. In Proceedings of the Fourth Swedish Language Technlogy Conference (SLTC2012), pages 79-80, Lund, Sweden.",
                "links": null
            }
        },
        "ref_entries": {
            "TABREF1": {
                "content": "<table/>",
                "num": null,
                "text": "",
                "html": null,
                "type_str": "table"
            },
            "TABREF3": {
                "content": "<table/>",
                "num": null,
                "text": "TagsetAlthough research in language identification and text classification shows that character and word n-gram-based methods outperform knowledge-rich features, we believe that these features are still worth experimenting with. Firstly, from an NLP perspective, these new features",
                "html": null,
                "type_str": "table"
            },
            "TABREF5": {
                "content": "<table><tr><td>Feature</td><td colspan=\"7\">ARGxMEX ARGxPER MEXxPER SPAxARG SPAxMEX SPAxPER Average</td></tr><tr><td>C 2-grams</td><td>0.999</td><td>0.996</td><td>0.860</td><td>0.852</td><td>0.957</td><td>0.940</td><td>0.934</td></tr><tr><td>C 3-grams</td><td>0.999</td><td>1.000</td><td>0.911</td><td>0.847</td><td>0.987</td><td>0.991</td><td>0.956</td></tr><tr><td>C 4-grams</td><td>1.000</td><td>0.999</td><td>0.922</td><td>0.827</td><td>0.992</td><td>0.996</td><td>0.965</td></tr><tr><td>C 5-grams</td><td>0.999</td><td>0.999</td><td>0.927</td><td>0.802</td><td>0.991</td><td>0.993</td><td>0.952</td></tr><tr><td>W 1-grams</td><td>0.999</td><td>0.999</td><td>0.945</td><td>0.851</td><td>0.994</td><td>0.992</td><td>0.963</td></tr><tr><td>W 2-grams</td><td>0.999</td><td>0.997</td><td>0.951</td><td>0.881</td><td>0.998</td><td>0.989</td><td>0.969</td></tr><tr><td>Average</td><td>0.999</td><td>0.998</td><td>0.919</td><td>0.843</td><td>0.986</td><td>0.983</td><td>0.955</td></tr></table>",
                "num": null,
                "text": "Confusion MatrixFrom the 500 texts from Spain used for testing, only 218 were correctly classified, 280 were tagged as Argentinian and 2 as Peru. We subsequently classified the varieties in binary settings. Results are reported in terms of accuracy and can be seen in table 5.",
                "html": null,
                "type_str": "table"
            },
            "TABREF6": {
                "content": "<table/>",
                "num": null,
                "text": "",
                "html": null,
                "type_str": "table"
            },
            "TABREF7": {
                "content": "<table><tr><td>Feature</td><td colspan=\"7\">ARGxMEX ARGxPER MEXxPER SPAxARG SPAxMEX SPAxPER Average</td></tr><tr><td>PoS 2-grams</td><td>0.766</td><td>0.650</td><td>0.742</td><td>0.637</td><td>0.831</td><td>0.702</td><td>0.721</td></tr><tr><td>PoS 3-grams</td><td>0.815</td><td>0.670</td><td>0.753</td><td>0.673</td><td>0.821</td><td>0.741</td><td>0.746</td></tr><tr><td>PoS 4-grams</td><td>0.823</td><td>0.732</td><td>0.737</td><td>0.690</td><td>0.806</td><td>0.667</td><td>0.743</td></tr><tr><td>Average</td><td>0.801</td><td>0.684</td><td>0.744</td><td>0.666</td><td>0.819</td><td>0.703</td><td>0.736</td></tr><tr><td/><td/><td colspan=\"4\">TABLE 6 -Classification with POS Tags</td><td/><td/></tr></table>",
                "num": null,
                "text": "word-based features, 0.986 on average. Accuracy results for all binary classification settings are presented in table 6.",
                "html": null,
                "type_str": "table"
            }
        }
    }
}