Unni Cathrine Eiken February 2005

The pre-editing of the text collection will naturally have affected the resulting EPAS list. All
structures from the original texts are not extracted and the EPAS list as a consequence does not
include all relevant context patterns for the domain. Still, for the purposes of a pilot study such
as in this thesis, the central structures, which display the most typical context patterns for the
domain, include enough information to provide a tendency of the usefulness of the method. For
the purpose of subsequent analyses, the extraction process can easily be performed on unedited
original texts.
3.5 Finding the words
The process of extracting meaning structures such as the EPAS from the texts in the text
collection is a substantial undertaking. It is also quite a tedious task, and since tedious tasks tend
to benefit from being automated I wrote the Perl script Ekstraktor, which interprets the MRS-
structures of a sentence and thereby puts together the EPAS for each parsed sentence. This
chapter describes the outline of the automated extraction process.
XLE provides the user with the choice of several output formats, including a graphical user
interface that displays a tree graph of the parse as well as its F-structure and MRS-structure. By
choice, the output can also be viewed as a file of Prolog predicates. In the process of extracting
the EPAS, Ekstraktor reads the Prolog output, saves relevant information in a system of arrays,
and subsequently performs several tests and actions on the stored information in order to present
a list of all EPAS found in the parsed sentence.
The MRS structures as represented in the Prolog output, provides all the information needed to
extract the EPAS. Initially, the main EP with belonging arguments must be found. Since for the
purpose of this paper, the linguistic structures analyzed are limited to full sentences, the main EP
must display the category ‘v’ for verb. Once the main EP is identified, the semantic values for it
and for its belonging arguments must be found. Subsequently, all the remaining predicateargument
structures must be found. For them, there is no restriction as to which category they
have. Consider the sentence shown in (3-12) together with an extract of the Prolog output of the
parse shown in (3-13):
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