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In-Depth Information
Transitive verbs:
kick, love, throw, make,
...
Intransitive verbs:
walk, sleep, die, listen,
...
Copula verbs:
be, seem,
...
Prepositions:
in, on, from, beside,
...
Others (pronouns, adverbs, interjections, ...)
Note that words can appear in more than one category. For example, the word
run
in
English is both a noun and a verb; the word
fat
is both a noun and an adjective.
8.1.2 Grammar
A
grammar
of a language is a specification of how the various types of words can
be grouped in the language. These word groups are called the syntactic
categories
.A
distinction is made between the following:
Lexical or
terminal
categories, like an article or a transitive verb. These will be
written in lowercase.
Group or
nonterminal
categories, like a phrase or a sentence. These will be written
in uppercase. (It is customary in linguistics to name the nonterminal categories
of a language using short, cryptic abbreviations like
NP
for noun phrase.)
Usually grammars are specified by a collection of
rules
(similar to Prolog clauses)
describing how each type of word group is formed from other word groups. For
present purposes, a grammar rule will have the following form:
category
category
1
category
2
...
category
n
where the category on the left must be nonterminal, and the categories on the right
(if any) can be terminal or nonterminal. For example, the grammar rule
PP
→
preposition NP
says that in English a prepositional phrase (
PP
) can be made up of a preposition
followed by a noun phrase (
NP
).
Figure 8.1 shows a grammar for some declarative sentences of English. Starting at
the top, the rule says that a sentence
S
can be made from a noun phrase
NP
followed by
a verb phrase
VP
. Note that this grammar does not include many features of English,
such as pronouns or clauses. Note also that the grammar is
recursive
: the category
Mods
(modifiers), for instance, is made up of zero or more of the
PP
category. This
allows stacking the modifiers, as in the following noun phrase:
the boy from France in
the library on the phone with the gray sweater
.
→
