PERSPECTIVES ON PARSING ISSUES 
Jane J. Robinson, Chair 
Artificial Intelligence Center 
SRZ International 
Nowhere is the tension between the two areas of our 
field--computatlon and llnguistlcs--more apparent than 
in the issues that arise in connection with parsing 
natural language input. This panel addresses those 
issues from both computational and linguisric 
perspectives. Each panelist has submitted a position 
paper on some of the questions that appear below. The 
questions are loosely grouped in three sections. The 
first concentrates on the computational aspect, the 
second on the linguistic aspect, and the third on their 
interactions. 
A preliminary definition: 
For purposes of providing common ground or possibly a 
common point of departure at the outset, I will define 
parsln~ as the assigning of labelled syntactic structure 
to an input by applying a grammar that defines 
syntactically well-formed sentences and phrases. Note 
that the question of whether the grammar does other 
things as well is left open. In this sense, parsing is 
distinguished from interpretation, which may take many 
forms, such as assigning representations in an 
unambiguous formal language and integrating those 
representations into a data base or into a hearer's 
belief system. 
The questions: 
I. Th_.__eeComputational Perspective: 
What useful purposes, if any, are served by 
distinguishing parsing from interpretation? Is 
computational efficiency increased? Is system building 
made easier? Or is an insistence on parsing a 
hindrance? (Can we compute an interpretation better 
without assigning l&belled syntactic structures?) 
Computational linguists, using available computational 
equipment that is almost exclusively serial in design, 
have devised parsing algorithms that involve serial 
search. Yet it is obvious that many parts of the 
parsing process could be done in parallel. How might 
notions of parallel processing, VLSI, and the llke 
change our views on parsing? 
What might motivate our trying to make parsing 
procedures simulate human behavior, e.g., by intermixing 
syntactic with semantic and pragmatic processing? And 
for that matter, how do we know what human processing is 
like? Do our intuitions agree and are they to be 
trusted? 
2. The Lin~uistlc Perspective: 
Have our tools (computers and formal grammars) warped 
our views of what human languages and human language 
processing may be like? What legitimate inferences 
about human linguistic competence and performance can we 
draw from our experiences with mechanical parsing of 
formal grammars? 
Our most efficient parsing algorithms are for context 
free (and even regular) grammars. Does this suggest 
that the core of grammars for natural languages is 
context free or even regular? 
3. The Interactions: 
Why do we usually have one grammar and procedure for 
sentence recognition and another grammar and procedure 
for sentence generation? Do we need a different pair 
for each direction? 
What is the nature of the relationship between a grammar 
and a procedure for applying it? Are we influenced in 
the way we devise computational grammars by the 
algorithms we expect to apply to them? Can a grammar be 
psychologically valid (validated) independently of the 
parsing algorithm that works with it? Can a parsing 
algorithm be psychologically valid (validated) 
independently of ~he grammar? 
The discussion to follow: 
The position papers will serve to focus the discussion. 
That discussion may take the form of a debate about the 
best methods for language processing, bot it can also be 
viewed as gathering of diverse experiences with 
processing n:tural language. 
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