74.419 Artificial Intelligence 2005/06

Features, Gaps, Movement Questions and Passives

Features, Gaps, and Questions

Features Questions Passives Gaps Movement

Sample Rule: (VP) (V SUBCAT -np-vp:inf) (NP) (VP VFORM inf)

Verb SUBCAT Feature

Example: (VP) (want SUBCAT -np-vp:inf) (class) (to end VFORM inf)

Sample Rule: (VP) (V SUBCAT -np-pp:loc) (NP) (PP PFORM LOC)

Prep. Phrases - PFORM Feature

Example: (VP) (put SUBCAT -np-pp:loc) (the tire) (on the cap PFORM loc)

Sample Rule: (VP) (V SUBCAT -np-adjp) (NP) (ADJP)

More Verb SUBCATs

Example: (VP) (held SUBCAT -np-adjp) (the cop) (responsible)

Auxiliaries - Some Features

Modal Verb

Complement Verb form 'base'e.g. did buy

person, number e.g. I, you, he, we, they did

Verb form 'past'e.g. did buy

Complement Verb form 'past participle'e.g. have seen

Verb form 'base'e.g. have paid

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

VP (AUX COMPFORM pastprt) (VP VFORM pastprt)

has brought

perfect, with pastparticiple

progressive

Questions

sentence / phrase: question Q, relative clause R

Category (POS), here:PP-word (prepositional phrase)

binary feature POSS: possessive

type, here: time specification

POS category, here: pronoun

agreement, matches: 3rd person singular or plural

type of PP, here: location, motion spec.

These characteristics give information about the type of the answer!

QDET: used as determiner

Features: POSS, WHRules for NP (noun phrase)

inheritance of features

Complement NP

PRO question word (possessive pronoun): who, whose (POSS +), which, what

QDET question (determiner):which (book), what (file)

from rule 1 (POSS +): whose (book)

PP question:where, when

PP with NP question:in which store, in whose pockets

Parsing Question - Which dogs did he see?

gap - NP missing

Passives

Active and Passive - Example

gap - NP missing

VP (AUX[be]) (VP[pastprt], +passgap)

was moved

VP[pastprt, +passgap] V[_np, pastprt]

moved

move is normally V[_np]

np is missing, thus +passgap

Passives - Example

The box was moved.

VP[pastprt, +passgap] (AUX[be]) (VP[pastprt], +passgap)

features are inherited downwards / passed upwards from main verb, VP (move, moved)

Movement

Additional References

James Allen: Natural Language Understanding. Benjamin Cummings, 1995