Discourse Production - 
A Computer Model of Some 
Aspects of a Speaker 
Anthony Davey 
Edinburgh Univ. Press, Scotland, 1978, 
170 pp., $16.00, ISBN 0-85224-339-1. 
"This book describes a computer program that 
produces English discourse. The program is capable of 
describing in a sequence of English sentences any 
game of noughts and crosses (tic-tac-toe), whether 
given or actually played with the program." (From 
the Preface.) 
The game descriptions have several properties that 
make them non-trivial. The entities of the game are 
referred to by fairly natural English noun phrases, 
making use of anaphora and standard constructions for 
qualification (such as relative clauses), and taking 
advantage of symmetry of the board. In many cases, 
moves are described for their strategic value, and some 
mistakes of the program's opponent are mentioned. 
The following sentence produced by the program illus- 
trates these properties. If you had blocked my line, 
you would have threatened me, but you took the corner 
adjacent to the one which you took first and so I won by 
completing my line. This also illustrates that the pro- 
gram uses connectors like and, but, so, and although, to 
string clauses together in coherent discourse. 
The grammatical theory used by the author is sys- 
temic grammar, essentially the version developed by R. 
A. Hudson in English Complex Sentences, North- 
Holland, 1971. In this theory, a grammatical item 
(such as a clause) is classified by an associated bundle 
of features. Feature-realization rules determine a set 
of functions (like SUBJECT) for constituents. 
Structure-building rules manipulate functions, gather- 
ing them into bundles, one for each constituent. 
Function-realization rules associate feature bundles 
with these function bundles, and the cycle continues, 
down to the word level. On each level there is some 
freedom of choice for the features of an item, but 
there is a network of constraints on co-occurring fea- 
tures called the system-network. 
In Davey's adaptation, semantic representations are 
carried along with the above sort of syntactic repre- 
sentations, and "specialist" procedures are used to 
determine features of grammatical items where there is 
freedom left in the system-networks. The overall con- 
trol, however, is not strictly top-down as in Hudson's 
system described above. Sometimes specialist proce- 
dures actually construct the English text for an item 
before determining all of its features. 
It is unfortunate that the book did not reach pub- 
lished form earlier. The work was done in the period 
1970-1973 as the author's thesis at Edinburgh Univer- 
sity. A chapter devoted to A Review of Previous Sys- 
tems essentially covers only what was published by 
1972. The program does not take account of advances 
made in systemic grammar since around 1972. Some 
of the constructions made by the program seem less 
direct than they should be, and this would be im- 
proved in the light of later developments. 
Michael C. McCord, University of Kentucky 
112 American Journal of Computational Linguistics, Volume 6, Number 2, April-June 1980 
