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

60 Chapter 4. Acquisition of Semantic Relations
1. Part of a grammar, with rules for extracting hypernymy (HIPERONIMO DE), part-of/haspart
(PARTE DE/TEM PARTE), and purpose-of (FAZ SE COM) relations, and the definitions
of an empty head (CABECA VAZIA):
RAIZ ::= HIPERONIMO DE ...
...
RAIZ ::= CABECA VAZIA
CABECA VAZIA ::= parte
...
RAIZ ::= ... usado para FAZ SE COM
RAIZ ::= parte de TEM PARTE
RAIZ ::= ... que contém DET PARTE DE
2. Dictionary entries (definiendum, POS, definition) and relations extracted using the
previous rules:
candeia nome utensílio doméstico rústico usado para iluminaç~ao, com
pavio abastecido a óleo
→ utensílio HIPERONIMO DE candeia
→ com FAZ SE COM candeia
→ iluminaç~ao FAZ SE COM candeia
espiga nome parte das gramíneas que contém os gr~aos
→ espiga PARTE DE gramíneas
→ gr~aos PARTE DE espiga
3. POS-tagging, cleaning and lemmatisation:
candeia nome utensílio#n doméstico#adj rústico#adj usado#v-pcp
para#prp iluminaç~ao#n ,#punc com#prp pavio#n
abastecido#v-pcp a#prp óleo#n
→ utensílio HIPERONIMO DE candeia
→ iluminaç~ao FAZ SE COM candeia
espiga nome parte#n de#prp as#art gramíneas#n que#pron-indp
contém#v-fin os#art gr~aos#n
→ espiga PARTE DE gramínea
→ gr~ao PARTE DE espiga
Figure 4.2: Extraction of semantic relations from dictionary definitions.
4.2 A large lexical network for Portuguese
The relation acquisition procedure was used to create CARTÃO (Gonçalo Oliveira
et al., 2011), a large term-based lexical-semantic network for Portuguese, extracted
from dictionaries. Regarding the incompleteness of dictionaries (Ide and Véronis,
1995)), we exploited not one, but three electronic dictionaries of Portuguese, namely:
• Dicionário PRO da Língua Portuguesa (DLP, 2005), indirectly with the results
of the project PAPEL;
• Dicionário Aberto (DA) (Simões and Farinha, 2011; Simões et al., 2012);
• Wiktionary.PT 6 .
6 Available from http://pt.wiktionary.org/ (September 2012)