IN ASSESSING THE USEFULNESS OF THE SEPARATION OF THE TRIPARTITE APP...

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