1. the subject of theoretical grammar its relations to other branches of linguistics

9. The syntactico-distributional classification of words is based on the study of their combinability by means of substitution testing. The testing results in developing the standard model of four main "positions" of notional words in the English sentence: those of the noun (N), verb (V), adjective (A), ad­verb (D).
Fries chooses tape-recorded spontaneous conversa­tions comprising about 250,000 word entries (50 hours of talk). The words isolated from this corpus are tested on the three typical sentences (that are isolated from the records, too), and used as substitution test-frames:
Frame A. The concert was good (always).
Frame B. The clerk remembered the tax (suddenly).
Frame C. The team went there.
As a result of successive substitution tests on the cited "frames" the following lists of positional words ("form-words", or "parts of speech") are established:
Class 1. (A) concert, coffee, taste, container, difference, etc. (B) clerk, husband, supervisor, etc.; tax, food, coffee, etc. (C) team, husband, wom­an, etc.
Class 2. (A) was, seemed, became, etc. (B) remembered, wanted, saw, suggested, etc. (C) went, came, ran,... lived, worked, etc.
Class 3. (A) good, large, necessary, foreign, new, empty, etc.
Class 4. (A) there, here, always, then, sometimes, etc. (B) clearly, suf­ficiently, especially, repeatedly, soon, etc. (C) there, back, out, etc.; rapid­ly, eagerly, confidently, etc.
All these words can fill in the positions of the frames without affecting their general structural meaning:
- the first frame; "actor - action - thing acted upon - characteristic of the action"
- the second frame; "actor - action - direction of the action"
- the third frame.
Comparing the syntactico-distributional classification of words with the traditional part of speech division of words, one cannot but see the similarity of the general schemes of the two: the opposition of notional and functional words, the four absolutely cardinal classes of notional words (since numerals and pronouns have no positional functions of their own and serve as pro-nounal and pro-adjectival elements), the in­terpretation of functional words as syntactic mediators and their formal representation by the fist.
However, under these unquestionable traits of similarity are distinctly revealed essential features of difference, the proper evaluation of which allows us to make some important generalizations about the structure of the lexemic system of language.