Syntax (1)

Syntax 1 (12-Feb-2004)

Background

In order to perform syntactic analysis, it is important to be aware of the criteria for the word classes:

nouns
verbs
adjectives - adjectives have degrees (e.g. sweet, sweeter, sweetest) and can often be turned into adverbs (sweetly)
prepositions
determiners and auxiliaries are useful as well

There are many exceptions, but in general there are standard criteria to decide what counts as an adjective, verb etc..

What happens when syntax goes wrong?

Pinker (p292) reports on the case of "Chelsea" who was born deaf and misdiagnosed as mentally retarded, until at age 31 an operation restored her hearing. Although she has since developed a vocabulary of two thousand words, her ability to form syntactically correct sentences is lacking, e.g.

The small a the hat
Banana the eat
The woman is bus the going

This contrasts with the result of studies of three children below the age of 5 in the Harvard study, where only ten out of many thousands of utterances showed syntactic position errors. Syntax relates to the ability to order grammatical elements correctly into a sentence, and this appears to be a separate ability to, e.g. morphology.

Categories of syntactic phrases

Syntax allows a phrasal constituent to substitute for a single word of a specific class. For example, a noun phrase is built on a single noun, and any sentence which contains a slot for a noun can receive any noun phrase in that slot while retaining syntactic sense.

The group of words that forms a phrasal constituent must remain together in an appropriate "slot" in the sentence: it may move around as a whole, but cannot be broken up. For example, the noun "birds" may be replaced by the noun phrase "a large bird with an orange beak", but that noun phrase must remain a single unit:

birds ate some food
some food was eaten by birds
the large bird with an orange beak ate some food
some food was eaten by the large bird with an orange beak

but you can't break it up and retain the sense:

*some the large bird food was eaten by with an orange beak

The slot occupied by a given noun phrase can be replaced by any other valid noun phrase and retain syntactic sense (although the semantic meaning may not be valid):

a cat ate some food
some food was eaten by a cat
*a some food was eaten by cat

The verb "waited" can be replaced by a verb phrase:

The young man waited
The young man waited for his friend
The young man has waited for his friend
*The has waited young man for his friend

The head word of a noun phrase is a noun, the head word of a verb phrase is a verb, etc.. The rest of the phrase complements the head word, completing its meaning. If a phrase in a sentence can be replaced by a noun, we know that the phrase is a noun phrase.

How else can we determine what counts as a phrasal constituent?

Apart from testing whether a word or phrase can substitute in a sentence for another word or phrase, there are other criteria we can use in trying to decide whether a given series of words is a phrasal constituent:

is it a conceptual unit, or a unit of sense?
In some cases, e.g. a noun phrase, it's fairly easy to say that "a red hat" is a conceptual unit, whereas the first three words of the sentence "you know how to do this" don't seem to be. Anything which is a conceptual unit will be a phrasal constituent (although the reverse isn't necessarily true).
In a sentence such as "the girl sailed up the river", up the river does form a conceptual unit, and this is a prepositional phrase. But not all prepositional phrases are easy to conceptualise, e.g. "the girl laughed at the monkey".
The unit of sense criterion seems to work best for noun phrases, adjective phrases and single verbs.

can it be replaced by a pro form?
For example, noun phrases can be replaced by pronouns: "she laughed at the monkey" can be changed to "she laughed at him". Verb phrases can also be replaced, e.g. "she laughed at the monkey and the boy did so" - in this case, "did so" means "laughed at the monkey", picking out the verb and its complement.

If a series of words represents a conceptual unit, then it is regarded as a phrasal constituent. E.g. "the red hat". However, not all phrasal constituents are conceptual units. For example, "at the monkey" is a prepositional phrase: that is, a phrase with a preposition as its head, and complemented by a noun phrase.

Analyzing the syntax of a sentence

A useful way to break down a sentence syntax involves building a tree of phrases, starting with the grammatical classes of individual words, and then finding head words and their complements (if any). For example, in the tree:

                                   S
                                  / \
                                 /   \
                                /     \
                               /       \
                              /         \
                             /           \
                            NP            VP
                            /\            /\
                           /  \          /  \
                         Det   N        V    PP
                          .    .        .    /\
                          .    .        .   /  \
                          .    .        .  P    NP
                          .    .        .  .    /\
                          .    .        .  .   /  \
                          .    .        .  .  det  N
                          .    .        .  .  .    .  
                        the  bird    flew up the  chimney

The sentence (S) consists of a NP and VP : S --> NP VP
The VP consists of a V and PP : VP --> V PP
The PP consists of a P and NP : PP --> P NP
The rightmost NP consists of a det and N : NP --> det N

Syntactic rules are expressed using this terminology, with parentheses being used for optional components. E.g.

NP --> (Det) (AP) N
i.e. a noun phrase is formed of an optional determiner, followed by an optional adjective phrase, followed by a noun.

These trees are phrase structure trees or constituent structure trees. Conventionally, the members of a tree are referred to using feminine relational terms (mother, sister, etc.).

Note that the phrase structure rules for English not universal: other languages have different rules.

Useful book readings for this lecture:

Crystal: "Encyclopedia of Language", pp 94-97
Fromkin+al "An Introduction to Language" pp 117-137
Pinker: "The Language Instinct" pp 292-293

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