74.419 Artificial Intelligence 2005/06

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74.419 Artificial Intelligence 2005/06

• Features, Gaps, Movement Questions and Passives

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Features, Gaps, and Questions

• Features
• Questions
• Passives
• Gaps
• Movement

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Verb SUBCAT Feature
Sample Rule (VP) ? (V SUBCAT -np-vpinf) (NP)
(VP VFORM inf)
Example (VP) ? (want SUBCAT -np-vpinf) (class)
(to end VFORM inf)
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Prep. Phrases - PFORM Feature
Sample Rule (VP) ? (V SUBCAT -np-pploc) (NP)
(PP PFORM LOC)
Example (VP) ? (put SUBCAT -np-pploc) (the
tire) (on the cap PFORM loc)
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More Verb SUBCATs
Sample Rule (VP) ? (V SUBCAT -np-adjp) (NP)
(ADJP)
Example (VP) ? (held SUBCAT -np-adjp) (the cop)
(responsible)
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Auxiliaries - Some Features
Modal Verb
Verb form 'past' e.g. did buy
person, number e.g. I, you, he, we, they did
Complement Verb form 'base' e.g. did buy
Verb form 'base' e.g. have paid
Complement Verb form 'past participle' e.g. have
seen
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VP ? (AUX COMPFORM base) (VP VFORM base)
can see
have to match (unification)
VP ? (AUX COMPFORM ?s) (VP VFORM ?s)
general form
VP ? (AUX COMPFORM ing) (VP VFORM ing)
is bringing
progressive
perfect, with past participle
VP ? (AUX COMPFORM pastprt) (VP VFORM pastprt)
has brought
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Questions
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Category (POS), here PP-word (prepositional
phrase)
These characteristics give information about the
type of the answer!
sentence / phrase question Q, relative clause R
type, here time specification
POS category, here pronoun
agreement, matches 3rd person singular or
plural
type of PP, here location, motion spec.
binary feature POSS possessive
QDET used as determiner
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Rules for NP (noun phrase)
PRO question word (possessive pronoun) who,
whose (POSS ), which, what
Features POSS, WH
from rule 1 (POSS ) whose (book)
Complement NP
QDET question (determiner) which (book), what
(file)
PP with NP question in which store, in whose
pockets
PP question where, when
inheritance of features
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Parsing Question - Which dogs did he see?
gap - NP missing
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Passives
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Active and Passive - Example
gap - NP missing
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Passives - Example

• The box was moved.

VPpastprt, passgap ? V_np, pastprt
moved move is normally V_np np is
missing, thus passgap
VP ? (AUXbe) (VPpastprt, passgap) was
moved
VPpastprt, passgap ? (AUXbe) (VPpastprt,
passgap) features are inherited downwards /
passed upwards from main verb, VP (move, moved)
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Movement
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Additional References

• James Allen Natural Language Understanding.
• Benjamin Cummings, 1995