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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
Requires massively redundant rules Fails to capture generalizations
S→NP-3p-sg VP-3p-sg S→NP-3p-pl VP-3p-pl S→NP1 VP1 S→NP2 VP2
Rules are arbitrary S→NP1 VP2
HPSG: How to Phix Subpar cfGs Change atomic categories into categories
that can be decomposed into features.
Let’s get our terms straight
universityNAME Stanford Univ.FOUNDERSPRESIDENTTEL
feature structure
typefeature value
More complex structures
Embedding, see p. 54, fig.7a Indexes
Department
TEL [1] 650-723-4284
CHAIR [TEL [1] ]
HPSG Types and Features
Initial type hierarchy, p. 61, fig. 25
HPSG Types and Features
Initial type hierarchy, p. 61, fig. 25 First important subtypes divide expressions
into words and phrases
HPSG Types and Features
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
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
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
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
A feature of expressions
The VAL feature
A feature of expressions Takes the value val-cat, which has the
features COMPS and SPR
The VAL feature
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
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
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
A generalization of the notion ‘determiner’ Distinguishes N, NOM, and NP SPR + for NP SPR – for NOM
The SPR feature
A generalization of the notion ‘determiner’ Distinguishes N, NOM, and NP SPR + for NP SPR – for NOM SPR + or SPR – for N
The SPR feature
A generalization of the notion ‘determiner’ Distinguishes N, NOM, and NP SPR + for NP SPR – for NOM SPR + or SPR – for N
Also used to distinguish S and VP 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
Round 1: lexical entries Round 2: p. 65, fig. 37a
Diagramming for Dollars
Round 1: lexical entries Round 2: p. 65, fig. 37a Round 3: p. 69, fig. 47
Agreement Rule
Agreement features get “passed up” from daughters to mothers
See rule, p. 70, fig. 50 Tree in 51
Head Feature PrincipleThere is a wisdom of the head…
--Charles Dickens
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
Round 1: lexical entries Round 2: p. 65, fig. 37a Round 3: p. 69, fig. 47 Round 4:
“LING7420 loves HPSG.”
“The professor cheers.”