involvement, and cannot be decomposed into smaller 
units (they are thus first articulation units). 
If such devices were to convey the totality of human 
experience, instead than as actually happens, a fairly 
limited number of messages, the first articulation units of 
their codes would need a tremendous increase in number, 
with ensuing problems for storage facilities. 
As to a structural semantics, a variety of views is present: 
firstly, Bloomfield declared as impossible the scientifical 
study of meanings: european scholars seem more trustful 
about possible structural models for lexicon. In the late 
fifties, Hjelmseev claimed that minimal meaningful units 
could be utterly decomposed into smaller units, resemling 
decomposition into phonems: for instance, “car” may be 
divided into small meaningful units as “vehicle”,+ “motor 
drive”+”four wheels”, and so on. 
The grammar of a language is a scheme able to specify 
sentences allowed in the language and to show the rules 
for merging words into propositions. 
In programs aimed to processing of natural language, the 
asset their meaning and draw an appropriate response. 
One of main contributions in this field was owed to 
Chomsky (1950), with this theory of formal languages. A 
formal language is said to be a set (possibly, infinite) of 
finite length strings, made with a finite vocabulary of 
symbols. 
The grammar of a formal language has the following 
basic concepts: 
■ syntactic categories, like “sentence” and “noun 
phrase”: they are said nonterminal symbols, or 
variables 
■ terminal symbols (that is, the words of a 
common language) which are assembled in the 
strings called sentences (A language is a subset in the 
general set of all possible strings which may 
assembled in all possible ways.) 
■ the laws of re-writing, or productions, which 
state relations among a number of strings 
■ the start symbol. 
The set of strings of terminal symbols that may derive 
from this symbol using the sequences of productions 
rules, is said the grammar generated language. 5 
5. Linguistics and AI 
Chomsky found four types of grammar, numbered from 0 
to 3. The zero-type grammar is the simplest one, having 
no restraint in re-writing laws. For further grammar the 
form of re-writing laws becomes more and more strict. 
For example, the grammar 3 (also said “context-free 
grammar”) can have only one single non-terminal symbol 
(on its left side) for every production. A context free 
grammar produces statements like ab, aabb, aaabbb. 
For instance: 
<SEN TENCE> -> <NOUN PHRASE><VERB 
PHRASE> 
<NOUN PHRASE> -> the <NOUN> 
<NOUN> -troad networks 
<NOUN> —»railway networks 
<VERB PHRASE> ->grow 
Chomsky (Syntactic structure, 1957) devised a theory of 
language to which refers transformational generative 
grammar:”a statement is the surface expression of a 
deeper structure, that is the real meaning of the 
statement”. 
The deep structure may suffer a number of formal 
changes (in the order of nouns, in suffixes,.etc.), as it 
comes to surfaces, although holding its substantial 
meaning. 
A new grammar of a language (like english) should be 
generative, that is a finite length statement able to: 
• take into account the infinity of possible statements 
in the said language 
• allot to any statement are structural description that 
may capture the knowledge of language for a typical 
individual 
Chomsky depicted for the grammar a 3-parts 
organization: 
■ the first part should have a phrasal structure 
which produces sets of morphemes for simple 
declarative statements, each holding a derivative tree 
■ a sequence of transformation rules should re 
assembles sentences, adding or deleting morphemes 
until the entire variety of possible sentences 
represented 
■ a sequence of morpho-phonemic rules should, at 
the end, map all representations of sentences with a 
set of phonemes. 
The feature of formal definitions of languages, from the 
viewpoints of computational linguistics and of processing 
of natural languages, is that the structure of statements is 
passed trough an algorithm of parsing, in order to be 
analyzed. 
Suppose that the phrase structure grammar has produced 
the following derivation tree. 
SENTENCE 
NOUN PHRASE VERB PHRASE 
NP-SINGULAR VERB NOUN PHRASE 
DET NOUN AUX V NP-PLURAL 
DET NOUN 
The wood TENSE 
the built area 
surrounds