THE ARGUMENT IN FAVOR OF THE TRIPARTITE APPROACH CITED INSTANCES OF...

2. The argument in favor of the tripartite approach

cited instances of nesting. The second consideration is

is roughly the following: many proponents of formal

that the determination of external functioning by con-

grammar claim that it is possible to construct a single

text searching is not a simple one-shot operation. It is

simple parsing algorithm to be used with any of several

not always possible to formulate a particular single

grammars of a certain type. The type of grammar has

context for a particular sequence that is to be ex-

to be specified very precisely by means of a grammar-

amined. Rather, the variety of contextual conditions

rule format. These grammars can be written in the

which may apply to a particular construction may dif-

form of tables of rules, and the same algorithm can be

fer from sentence to sentence, and the particular con-

ditions that apply can be determined only by a gradu-

* Work on this paper was done under the sponsorship of the

ated search of a potentially ever extending range of

Information Processing Laboratory of the Rome Air Development

contexts. This means that one cannot simply talk of

Center of the United States Air Force, under Contract AF30(602)-