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Linguistics II
Syntax
Syntax
• Rules of how words go together to form
sentences
• What types of words go together
• How the presence of some words
predetermines others
• What sequences are legitimate?
Word classes
• Classic “parts of speech”
– closed class (grammatical words):
• Prepositions, articles, pronouns, …
– open class (lexical words):
• nouns, verbs, adjectives, adverbs
• How to define word classes
– Form
– Function
– Meaning
How to define word classes
• Form (what they look like)
– Distinctive “appearance”
– morphological behaviour (what inflections can
they take?)
• Function (what they do)
– What other words do they co-occur with?
• Meaning (what they mean)
– E.g. word which names something, doing
word, word which describes a quality
How to define word classes
• Structuralism: substitution classes
The very old
man walked slowly down the street
The very young man walked slowly down the street
The rather young man walked slowly down the street
That rather young man walked slowly down the street
That rather young woman walked slowly down the street
That rather young woman ran slowly down the street
That rather young woman ran quickly down the street
That rather young woman ran quickly up the street
How to define word classes
• Structuralism: constituents
The very old
The
old
The
He
He
He
The very
The very
old
old
man walked slowly down the street
man walked slowly down the street
man walked slowly down the street
walked slowly down the street
walked slowly
there
will walk slowly
there
man walked slowly down the street
man walked slowly down the street
How to define word classes
• Structuralism: constituents
NP
Verb group
AdjP
The very old
The
old
The
He
He
He
AdvP
man walked slowly down the street
man walked slowly down the street
man walked slowly down the street
walked slowly down the street
walked slowly
there
will walk slowly
there
Grammar
• Tries to capture the range of possible
sentences in “rules”
• Most common type is a “context-free
grammar” using a “rewrite rule formalism”
• (We’ll explain “context-free” later)
Simple grammar
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S → NP VP
S → NP VP adv
NP → det n
NP → det AdjG n
NP → det n PP
NP → det AdjG n PP
PP → prep NP
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VP → v
VP → v NP
VP → v NP PP
VP → v NP
VP → v PP
AdjG → adj
AdjG → adv adj
Lexicon
det → {the,this,these,a,an}
n → {man,girl,men,girls,apple,street,bowl}
prep → {with,to,from,in}
v → {eat,eats,ate,speak,speaks,spoke,come,comes,came}
adj → {big,old,pretty,delicious}
adv → {very,rather,quickly}
Simple grammar
• Notice that rules always have only one
symbol on the left-hand side, any number
of symbols on the right
• Terminal and non-terminal symbols
• Rule could be simplified with some
additional notation, e.g. brackets to show
optionality
– NP → det (AdjG) n (PP)
Tree structures
S
NP
det
VP
n
v
PP
prep
the
boy
spoke
to
NP
det
n
the
girl
Tree structures
S
VP
PP
NP
NP
det
n
v
the
boy
spoke
prep det
to
the
n
girl
Simple grammar
• Notice that the rules (despite the direction of the
arrow) can be used to produce strings (starting
from a left-hand side) or to verify that a given
string is grammatical (and to say what its
structure is)
• What sentences does the grammar account for?
• The grammar generates some strings which we
judge to be ungrammatical. Why?
Subcategorization
• One way to solve overgeneration would be
to have more specific categories, e.g.
– VP → vitr
– VP → vtr NP
• Not so attractive, because it would lead to
duplication of many rules, and loss of
generalization
• As a compromise, rules can have
additional conditions in the form of
features
Simple grammar with features
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S → NP[num=X] VP[num=X]
NP[num=X] → det[num=X] n[num=X]
NP[num=X] → det[num=X] AdjG n[num=X]
VP[num=X] → v[num=X,type=itr]
VP[num=X] → v[num=X,type=tr] NP
etc
Lexicon
det[num=sing] → {the,this,a,an}
det[num=plur] → {the,these}
n[num=sing] → {man,girl,apple,street,bowl}
n[num=plur] → {men,girls}
v[num=sing,type=itr]→ {eats,ate,speaks,spoke, comes,came}
v[num=plur,type=itr] → {eat,ate,speak,spoke,come,came}
v[num=sing,type=tr] → {eats,ate}
v[num=plur,type=tr] → {eat,ate}
Grammatical functions
• Context-free grammar defines
constituency and structure …
• … but says nothing about function
• Sentence-level functions are things like
subject, object
• Within noun-phrases: determiners,
modifiers
• In each constituent, one element may be
identified as the head
Complements and adjuncts
Consider: The man smashed the vase with a
hammer yesterday by accident.
• ‘Complements’ are arguments closely
connected to the verb, without which the
sentence is ungrammatical
• ‘Adjuncts’ add meaning to the proposition
as a whole, and are generally optional
Complements
• Predictable from (or definitive of) the
verb’s ‘subcategorization frame’
• May be compulsory or optional
• Verb specifies its complements in form,
function and content
– Form: NP, PP, that-S, infinitive, …
– Function: subject, object, prep-obj, …
– Content: syntactic or semantic features
Word order
• Grammar defines word-order
• Globally, languages can be classified according
to basic word-order:
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–
–
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SVO (verb-medial, eg English)
SOV (verb-final, eg Hindi, Japanese, German)
VSO (verb-initial, eg Arabic, Welsh)
these are the most common
• SVO also means typical NP is det n mod, “verbfinal” actually means “head-final”, etc.
Word order
• Some languages have “free word-order” though
few are completely free, and choice of wordorder usually carries pragmatic significance;
Finnish said to be completely free word-order
• Many allow “scrambling”, eg Japanese, German
have free word-order as long as verb is final
• Word-order often indicates grammatical function
(eg English), so free word-order languages must
compensate, usually with lots of inflectional
morphology