Scope

Revision as of 22:05, 10 July 2010

The UNL representation is a hyper-graph and may consist of several interlinked or subordinate sub-graphs, which are used to define the boundaries and the scope of the semantic entities being represented. These sub-graphs correspond roughly to the concept of "clauses", i.e., groups of words that consist of a subject and a predicate. For instance, the sentence "Mary saw Peter when John arrived" is represented, in UNL, as follows:

In the above, the dependent clause "John arrived" is represented as a hyper-node linked to the main clause by the relation "tim" (which corresponds to the value of the conjunction "when"). In the UNL table representation, hyper-nodes are indexed by ":XX", where XX is a two-digit hyper-node index. Hyper-node indexes must also be associated to every relation inside the node.

agt:00(saw, Mary)
obj:00(saw, Peter)
tim:00(saw, :01)
agt:01(arrived, John)

They are said to be independent if they can stand alone as a sentence, or dependent (embedded, subordinate), otherwise. In the UNL framework, dependent clauses are represented as hyper-nodes (the so-called scopes) linked to the main clause, as indicated below:

• English: Mary saw Peter when John arrived.
  • Mary saw Peter (independent clause)
  • when John arrived (dependent clause)
• UNL:
  • Mary saw Peter (independent clause) = agt(saw, Mary), obj(saw,Peter)
  • John arrived (dependent clause) = agt:01(arrived, John)
  • dependency relation = tim(saw, :01)

Where :01 (to be assigned to every relation inside the scope) is the scope index.