3. In assessing the usefulness of the separation of
The tripartite approach is based on a strict separation
grammar and algorithm, it is important to keep in
of grammar and algorithm; the parsing program here
consists of three basic portions: the machine dictionary
mind the well-known distinction between context-free
and context-sensitive grammars. In this author’s frame
with grammar codes, a stored grammar, and a parsing
of reference, this distinction can be formulated very
algorithm which utilizes the codes furnished by the
dictionary and applies the grammar.
simply as follows: a context-free grammar is one in
The purpose of this paper is to examine the validity
which only the internal structure of a given construc-
of the frequently repeated contention that the tripartite
tion is taken into account; a context-sensitive one is
one in which both the internal structure and the exter-
approach, consisting in the separation of algorithm and
nal functioning are taken into account. This view fol-
grammar, is particularly desirable in automatic-parsing
lows from the conception that internal structure and
programs. This examination will be restricted to the
external functioning are two separate, related, but not
area of automatic parsing of natural languages with
identical, functional characteristics of the units of
particular attention to the parsing problems encoun-
language such as syntactic units.
tered in machine translation.
There are two important considerations which follow
It must be noted at the outset that in this author’s
from this. One is that very often the internal structure
opinion the aim of the automatic-parsing component
of a construction is not adequate to determine its ex-
of a machine-translation program is the adequate
ternal functioning. The well-known fact must be taken
recognition of the boundaries and functions of syntac-
into account that sequences with identical internal
tic units. On the basis of this recognition, automatic
structure may have vastly different modes of external
translation on a sentence-by-sentence rather than a
functioning and conversely. Examples of this are very
word-by-word basis can be effected.
common in English and include many of the frequently
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