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

Chapter 8
Onto.PT: a lexical ontology for
Portuguese
In the previous chapters, we have presented individual automatic steps towards
the acquisition and integration of lexical-semantic knowledge in a LKB. Each step
is implemented by a module and, if combined with the others, as described by the
diagram in figure 8.1, results in the three step approach we propose to the automatic
construction of a wordnet-like resource. This approach was named ECO, which
stands for Extraction, Clustering and Ontologisation. Briefly, the ECO approach
starts by extracting instances of semantic relations, represented as tb-triples, from
textual sources. Then, synsets are discovered from the extracted synonymy tbtriples
(synpairs). If there is a an available synset-based thesaurus, its synsets are
first augmented, and new synsets are only discovered from the remaining synpairs.
Finally, the term arguments of the non-synonymy tb-triples are ontologised, which
means that they are attached to the synsets, in the thesaurus, that transmit suitable
meanings and make the tb-triple true. This results in a wordnet, where synsets are
connected by semantic relations (sb-triples).
Figure 8.1: Diagram of the ECO approach for creating wordnets from text.
Each module of ECO is completely independent of the others and can be used
alone, in order to achieve its specific task. For instance, given a set of synpairs,
an existing thesaurus may be enriched automatically and have its original synsets