Onto.PT: Towards the Automatic Construction of a Lexical Ontology ...

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144 Chapter 8. Onto.PT: a lexical ontology for Portuguese To give an idea on the quality of each relation type, table 8.6 presents the results of the evaluation of the 300 non-hypernymy tb-triples. The number of evaluated sb-triples is not enough to take strong conclusions, but the quantity of dizSeDoQue correct tb-triples stands out. It is higher than the extraction accuracy of these relations (adj property-of v, 71-77% correct in section 4.2.5) from dictionaries. Given that most of the problems about these relations were due to incorrect arguments, we view this improvement as a consequence both of the new lemmatisation rules, and of the removal of tb-triples with arguments not occurring in the corpus, performed before ontologisation. On the other hand, the quality of the parteDe sb-triples is quite low. Similarly to what happens with hypernymy, the main problem about this relation seems to be the ambiguity and underspecification of its arguments. This has a negative impact both on the establishment of correct synsets with these words and on the ontologisation of tb-triples. 8.3.3 Global coverage If compared to the number of sb-triples in Princeton WordNet 3.0 (see section 3.1.1), developed manually between 1985 and 2006, Onto.PT v.0.35 is larger because all of its relations can be inverted. This means that Onto.PT contains about 346,000 sb-triples against the 285,000 of WordNet 3.0. This number, which may soon increase, if more resources are exploited, highlights the potential of an automatic approach. As this number is insufficient to quantify the coverage of Onto.PT, we evaluated its coverage of base concepts, that should be represented in wordnets. The Global WordNet Association 5 provides several lists with this kind of concepts. One of them contains 164 base concepts, referred to as the “most important” in the wordnets of English, Spanish, Dutch and Italian 6 . The concepts are divided into 98 abstract and 66 concrete, and are represented as Princeton WordNet 1.5 synsets. In order to evaluate the global coverage of Onto.PT, we tried to make rough matches, manually, between the 164 base concepts and Onto.PT synsets. Given the WordNet synset denoting each of the 164 concepts, we selected the Onto.PT synset closer to its meaning. In the end, we concluded that Onto.PT roughly covers most of the concepts in the list, more precisely 92 abstract and 61 concrete synsets (93%). All the defined matches are reported in the appendix B of this thesis. More precisely, the concrete concepts are in table B.1, and the abstract in tables B.2. There, we can see that the Onto.PT synsets are, on average, larger than WordNet’s, which means, on the one hand, that they are very rich, with many synonyms – most synsets include various levels of language (formal, informal, figurative, older forms...) and variants of Portuguese (Portugal, Brazil, Africa). This can be very useful for tasks from information retrieval (see section 8.4.3) to creative writing (e.g. poetry). On the other hand, the matches show that there are synsets that go beyond including only synonyms – most noisy items are more like near-synonyms and some are closely related words. Considering just the abstract concepts not covered by Onto.PT (e.g. change magnitude, definite quantity, visual property), they seem to have been created ar- 5 See website at http://www.globalwordnet.org/ (September 2012) 6 See more about this list in http://www.globalwordnet.org/gwa/ewn_to_bc/corebcs.html (September 2012)
8.3. Evaluation 145 Relation parteDe 15 10 parteDeAlgoComPropriedade 20 18 membroDe 17 14 propriedadeDeAlgoMembroDe 4 4 contidoEm 2 2 contidoEmAlgoComPropriedade 1 1 materialDe 4 4 causadorDe 5 5 propriedadeDeAlgoQueCausa 2 2 accaoQueCausa 32 30 produtorDe 7 4 propriedadeDeAlgoProdutorDe 1 1 fazSeCom 24 22 fazSeComAlgoComPropriedade 1 1 finalidadeDe 24 21 localOrigemDe 4 4 temQualidade 2 2 devidoAQualidade 11 10 devidoAEstado 1 1 antonimoNDe 5 5 antonimoAdvDe 1 1 antonimoVDe 6 9 antonimoAdjDe 9 8 dizSeSobre 29 29 dizSeDoQue 53 48 maneiraPorMeioDe 9 8 maneiraComPropriedade 7 6 Quantity Correct Judge A B A B IAA J1 J2 33.3% 46.7% 50.0% 70.0% 80.0% J1 J2 85.0% 80.0% 94.4% 88.9% 94.4% J1 J2 82.4% 82.4% 100% 100% 100% J1 J2 75.0% 100% 75.0% 100% 75.0% J1 J2 100% 50.0% 100% 50.0% 50.0% J1 J2 100% 100% 100% 100% 100% J1 J2 75.0% 100% 75.0% 100% 75.0% J1 J2 100% 80.0% 100% 80.0% 80.0% J1 J2 50.0% 50.0% 50.0% 50.0% 100% J1 J2 84.4% 90.6% 90.0% 96.7% 93.3% J1 J2 42.9% 28.6% 75.0% 50.0% 75.0% J1 J2 100% 100% 100% 100% 100% J1 J2 70.8% 75.0% 77.3% 81.8% 86.4% J1 J2 100% 100% 100% 100% 100% J1 J2 70.8% 83.3% 81.0% 95.2% 85.7% J1 J2 50.0% 75.0% 50.0% 75.0% 75.0% J1 J2 100% 100% 100% 100% 100% J1 J2 81.8% 90.9% 90.0% 100% 90.0% J1 J2 100% 100% 100% 100% 100% J1 J2 80.0% 80.0% 80.0% 80.0% 100% J1 J2 100% 100% 100% 100% 100% J1 J2 66.7% 66.7% 100% 100% 100% J1 J2 88.8% 88.8% 100% 100% 100% J1 J2 96.6% 93.1% 96.6% 93.1% 96.6% J1 J2 81.1% 88.7% 90.0% 97.9% 87.5% J1 J2 88.9% 88.9% 100% 100% 100% J1 J2 85.7% 85.7% 100% 100% 100% Table 8.6: Results of the manual evaluation of sb-triples per relation type. tificially, and work as “covert categories” of more specific concepts. All the verb synsets are covered by Onto.PT. If we compare these results with the coverage of the concepts by MWN.PT, Onto.PT covers all the verbs, which are not included in MWN.PT. Furthermore, despite covering the concepts of human action and magnitude relation, their correspondence in MWN.PT are gaps, possibly because its authors did not find a suitable translation for them. Onto.PT does not cover the latter concept too, but we could find a suitable match for the former (feito, obra,
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PhD Thesis Doctoral Program in Info
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Preface About six years ago, almost
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Resumo Não há grandes dúvidas qu
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Contents Chapter 1: Introduction .
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8.2.1 Semantic Web model . . . . .
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6.1 Illustrative synonymy network.
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6.3 Evaluation against intersection
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Chapter 1 Introduction A substantia
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1.2. Approach 5 • They are not bu
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1.4. Outline of the thesis 7 which
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Chapter 2 Background Knowledge The
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2.1. Lexical Semantics 11 that, in
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2.1. Lexical Semantics 13 Meronymy
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2.2. Lexical Knowledge Formalisms a
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2.3. Information Extraction from Te
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2.3. Information Extraction from Te
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2.4. Remarks on this section 25 usi
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28 Chapter 3. Related Work in group
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30 Chapter 3. Related Work ple rela
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32 Chapter 3. Related Work knowledg
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34 Chapter 3. Related Work the ELRA
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36 Chapter 3. Related Work resource
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38 Chapter 3. Related Work English
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40 Chapter 3. Related Work of super
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42 Chapter 3. Related Work • part
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44 Chapter 3. Related Work LSIE fro
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46 Chapter 3. Related Work modifier
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48 Chapter 3. Related Work 6. {,}
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50 Chapter 3. Related Work 1. Extra
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52 Chapter 3. Related Work Due to t
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54 Chapter 3. Related Work comparis
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56 Chapter 3. Related Work creation
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58 Chapter 4. Acquisition of Semant
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80 Chapter 5. Synset Discovery Ther
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82 Chapter 5. Synset Discovery the
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84 Chapter 5. Synset Discovery tb-t
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86 Chapter 5. Synset Discovery cota
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88 Chapter 5. Synset Discovery θ W
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90 Chapter 5. Synset Discovery Tabl
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92 Chapter 5. Synset Discovery word
Page 113 and 114: Chapter 6 Thesaurus Enrichment Gene
Page 115 and 116: 6.1. Automatic Assignment of synpai
Page 117 and 118: 6.2. Evaluation of the assignment p
Page 119 and 120: 6.3. Clustering and integrating new
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Page 149 and 150: Chapter 8 Onto.PT: a lexical ontolo
Page 151 and 152: 8.1. Overview 133 items inside a sy
Page 153 and 154: 8.2. Access and Availability 135 no
Page 155 and 156: 8.2. Access and Availability 137 Ex
Page 157 and 158: 8.3. Evaluation 139 Figure 8.3: Ins
Page 159 and 160: 8.3. Evaluation 141 the most reliab
Page 161: 8.3. Evaluation 143 imation of the
Page 165 and 166: 8.4. Using Onto.PT 147 • S: (n) a
Page 167 and 168: 8.4. Using Onto.PT 149 todos os fun
Page 169 and 170: 8.4. Using Onto.PT 151 In addition
Page 171 and 172: 8.4. Using Onto.PT 153 based approa
Page 173: 8.4. Using Onto.PT 155 Uma populaç
Page 176 and 177: 158 Chapter 9. Final discussion 3.
Page 178 and 179: 160 Chapter 9. Final discussion - G
Page 180 and 181: 162 Chapter 9. Final discussion Any
Page 183 and 184: References Agichtein, E. and Gravan
Page 185 and 186: References 167 for storing and quer
Page 187 and 188: References 169 15th International C
Page 189 and 190: References 171 Symposium (STAIRS 20
Page 191 and 192: References 173 Hovy, E., Hermjakob,
Page 193 and 194: References 175 ACM, 38(11):39-41. M
Page 195 and 196: References 177 ACL Press. Partee, B
Page 197 and 198: References 179 Russell, S. and Norv
Page 199 and 200: References 181 Proceedings of 13th
Page 201 and 202: Appendix A Description of the extra
Page 203 and 204: • x propriedadeDeAlgoQueCausa y -
Page 205: • x antonimoAdjDe y Property - x
Page 208 and 209: 190 Appendix B. Coverage of EuroWor
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194 Appendix B. Coverage of EuroWor
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