Spotlight: Semantic processing
A module performing annotation at the tectogrammatical layer is run after the syntactic parse is available. Annotation of the meaning of a sentence at tectogrammatical layer is more explicit than its syntactic parse and lends itself for information extraction.
Semantic parsing resolves:
- Assignment of one of 69 semantic roles
- Argument structure
- Partial ellipsis resolution
- Pronominal anaphora resolution.
The semantic tree structure is derived from the syntactic parse by set of rules, tree attributes are filled using fnTBL toolkit trained on PDT 2.0 corpora. Post-parsing detection and correction of ungrammatical edges caused by long user utterances is rule based.
The resulting semantic tree is matched against tree fragments using a tree querying engine PMLTQ developed at Charles University. Queries predicates cover topics from Wizard-of-Oz corpora that were implemented in form of DAFs. Extracted information is stored by Dialog Manager in Perl objects.