Eckhard Bick - VISL

6
The semantic perspective:
Incremental Semantic Parsing (ISP)
6.1 Semantic tagging
Language analysis in a parsing perspective (both manual and automatic) is traditionally
subdivided into different levels, where different applications take an interest in different
levels. Thus a morphological or word class (PoS) analysis may be satisfactory for
corpus based lexical frequency analyses, while internet based grammar teaching as in
the VISL project (Bick 1998 and http://visl.hum.sdu.dk) needs syntactic, and machine
translation needs semantic analysis.
One might assume that each of these levels needs its own parsing tools, - for instance,
probabilistic tools for PoS-tagging, generative grammars for syntactic parsing and
logical meta-languages for the semantic level. My research, however, indicates that it is
possible to extend at least one rule based tool - Constraint Grammar - to ever “higher”
levels of analysis - provided a lexical data base containing the necessary lexicographic
information is developed in parallel. One could say that in the case of Constraint
Grammar, the quality and granularity of the analysis is not inherent in the technique, but
rather goal driven, and that it can be improved in an incremental way.
Are semantic tags practical?
After morphological and syntactic tagging the next logical step in Progressive Level
Parsing appears to be the semantic tagging of word items. But is semantic tagging
possible, and is tagging a sensible approach at all to the semantic analysis of free text?
Clearly, in terms of referent resolution or information content, any type of semantic
analysis of NL texts is a task not to be fully resolved in the near future, - whatever the
notational conventions used. Since human language is intertwined with human
intelligence and human knowledge, full semantic analysis will not work without a
certain degree of artificial intelligence and a huge bank of "knowledge about the
world", both unavailable at the present time.
Nevertheless, in a more limited sense, semantic tags can be useful for present day
tasks:
For one, semantic tags can be used, as secondary tags, for the disambiguation of
syntactic ambiguity. , for instance, in a noun connected to the verb "build",
would rule out the object reading, and favour a subject reading, in a language where
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