Transcript Susan`s Powerpoint slides on Sag et al., Chapter 3

Analyzing Features of
Grammatical Categories
Show my head to the people; it is worth
seeing.
--Feature structure, to Ivan Sag in a dream
CFG’s: Chock Full of Goofs
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Requires massively redundant rules
Fails to capture generalizations
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S→NP-3p-sg VP-3p-sg
S→NP-3p-pl VP-3p-pl
S→NP1 VP1
S→NP2 VP2
Rules are arbitrary
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S→NP1 VP2
HPSG: How to Phix Subpar cfGs
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Change atomic categories into categories
that can be decomposed into features.
Let’s get our terms straight
type
feature
university
NAME
FOUNDERS
PRESIDENT
TEL
value
Stanford Univ.
feature structure
More complex structures
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Embedding, see p. 54, fig.7a
Indexes
Department
TEL [1] 650-723-4284
CHAIR [TEL [1] ]
HPSG Types and Features
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Initial type hierarchy, p. 61, fig. 25
HPSG Types and Features
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Initial type hierarchy, p. 61, fig. 25
First important subtypes divide expressions
into words and phrases
HPSG Types and Features
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Initial type hierarchy, p. 61, fig. 25
First important subtypes divide expressions
into words and phrases
All expressions have the feature HEAD
HPSG Types and Features
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Initial type hierarchy, p. 61, fig. 25
First important subtypes divide expressions
into words and phrases
All expressions have the feature HEAD with a
value from the pos types
HPSG Types and Features
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Initial type hierarchy, p. 61, fig. 25
First important subtypes divide expressions
into words and phrases
All expressions have the feature HEAD with a
value from the pos types
Agreement
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Some pos types exhibit agreement, so we
group them into their own subtype agr-pos,
which carries the feature AGR
AGR feature takes the value agr-cat, which is
a sub-type of feature-structure
It has (at least) the features PER and NUM
PER takes the values {1st,2nd,3rd}
NUM takes the values {sg, pl}
See p. 70, fig. 49
How much of this is universal?
Other languages have different values?
All languages have all features and values, but
optimality-like constraints ensure that only
some show up?
The VAL feature
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A feature of expressions
The VAL feature
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A feature of expressions
Takes the value val-cat, which has the
features COMPS and SPR
The VAL feature
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A feature of expressions
Takes the value val-cat, which has the
features COMPS and SPR
These “represent the combinatoric potential
of the word or phrase”
The VAL feature
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A feature of expressions
Takes the value val-cat, which has the
features COMPS and SPR
These “represent the combinatoric potential
of the word or phrase”
COMPS takes the value itr, str, or dtr; p.62,
fig. 27
All expressions have this feature (so far)
Underspecification
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A type can be unspecified for a particular
feature
This picks out a larger class of feature
structures (it includes more kinds of feature
structures)
Underspecification allows some kinds of
generalizations that we couldn’t get from
CFGs, p. 63, fig.28
The SPR feature
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A generalization of the notion ‘determiner’
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Distinguishes N, NOM, and NP
SPR + for NP
SPR – for NOM
The SPR feature
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A generalization of the notion ‘determiner’
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Distinguishes N, NOM, and NP
SPR + for NP
SPR – for NOM
SPR + or SPR – for N
The SPR feature
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A generalization of the notion ‘determiner’
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Distinguishes N, NOM, and NP
SPR + for NP
SPR – for NOM
SPR + or SPR – for N
Also used to distinguish S and VP
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S is SPR +
VP needs a subject NP to the left, so it is SPR –
Huh? p. 64, fig. 34
Diagramming for Dollars
Diagramming for Dollars
Team 1: lexical entry for the noun “verb”
As in, “Weird can be a verb”
Team 2: lexical entry for the verb “verbs”
As in, “Calvin verbs the word ‘weird’.”
Diagramming for Dollars
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Round 1: lexical entries
Round 2: p. 65, fig. 37a
Diagramming for Dollars
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Round 1: lexical entries
Round 2: p. 65, fig. 37a
Round 3: p. 69, fig. 47
Agreement Rule
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Agreement features get “passed up” from
daughters to mothers
See rule, p. 70, fig. 50
Tree in 51
Head Feature Principle
There is a wisdom of the head…
--Charles Dickens
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Every headed phrase has a head daughter
with the same head values
General form: p. 72, fig. 53
Headed rules: p. 73, fig. 54, esp. 54d
Diagramming for Dollars
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Round 1: lexical entries
Round 2: p. 65, fig. 37a
Round 3: p. 69, fig. 47
Round 4:
“LING7420 loves HPSG.”
“The professor cheers.”