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LING 388: Language and Computers. Sandiway Fong Lecture 17: 10/24. Administrivia. homework 5 due this Thursday. Administrivia. Computer Lab Class on Thursday meet in SS 224 there will be no homework just class exercises ( to be assumed in homework 6 )

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ling 388 language and computers

LING 388: Language and Computers

Sandiway Fong

Lecture 17: 10/24

administrivia
Administrivia
  • homework 5
    • due this Thursday
administrivia1
Administrivia
  • Computer Lab Class
    • on Thursday
    • meet in SS 224
    • there will be no homework
    • just class exercises
      • (to be assumed in homework 6)
    • we’ll continue implementing more of the grammar for passivization etc.
today s topic
Today’s Topic
  • case study
    • How to implement the passive construction
      • verb inflection
      • constraints between auxiliary and main verbs
      • subcategorization and adjuncts
example grammar
Example Grammar
  • grammar so far
    • including extra arguments for parse tree
    • and simple determiner-noun agreement
    • s(s(Y,Z)) --> np(Y), vp(Z).
    • np(np(Y)) --> pronoun(Y).
    • np(np(D,N)) --> det(D,Number), common_noun(N,Number).
    • det(det(the),_) --> [the].
    • det(det(a),sg) --> [a].
    • common_noun(n(ball),sg) --> [ball].
    • common_noun(n(man),sg) --> [man].
    • common_noun(n(men),pl) --> [men].
    • pronoun(i) --> [i].
    • pronoun(we) --> [we].
    • vp(vp(Y)) --> unergative(Y).
    • vp(vp(Y,Z)) --> transitive(Y), np(Z).
    • unergative(v(ran)) --> [ran].
    • transitive(v(hit)) --> [hit].
  • query
    • ?- s(X,Sentence,[]). Sentence = Prolog list of words

all rules take one

extra argument for the

parse tree

however

det and common_noun

take two extra arguments:

one for the parse tree

and one for Number

verb classes

only one extra argument for the parse tree

passivization
in English...

passivization applies only to transitive verbs

I hit the ball (active)

the ball was hit (passive)

transitive(v(hit)) --> [hit].

i.e. passivization should only apply to verbs encoded in the grammar using the transitive non-terminal

not for unaccusative or unergative verbs

I arrived

*I was arrived

unaccusative(v(arrived)) --> [arrived].

We ran

*We were ran/run

unergative(v(ran)) --> [ran].

Passivization
passivization1

s

np

vp

s

v

np

i

det

n

vp

hit

np

ball

the

aux

v

det

n

ball

the

was

hit

Passivization
  • simple phrase structure
    • I hit the ball (active)
    • the ball was hit (passive)

(non-movement account)

  • avoiding empty categories for simplicity (can be added):
  • the ball was hit e
  • [the ball]i was hit ti
passivization2

s

vp

np

aux

v

det

n

ball

the

was

hit

Passivization
  • phrase structure
    • the ball was hit (passive)
  • rules (active sentence)
    • s(s(Y,Z)) --> np(Y), vp(Z).
    • vp(vp(Y,Z)) --> transitive(Y), np(Z).
    • transitive(v(hit)) --> [hit].
  • new rules (passive sentence)
    • vp(vp(A,V)) --> aux(A), transitive(V).
    • aux(aux(was)) --> [was].
passivization3
Passivization
  • query
    • ?- s(X,[the,ball,was,hit],[]).
  • computation tree
    • ?- s(X,[the,ball,was,hit],[]).
      • ?- np(Y,[the,ball,was,hit],L).
      • ?- vp(Z,L,[]).
    • ?- np(Y,[the,ball,was,hit],L).
      • Y=np(det(the),n(ball)) L=[was,hit]
    • ?- vp(vp(A,V),[was,hit],[]).
      • ?- aux(A,[was,hit],L’).
      • ?- transitive(V,L’,[]).
    • ?- aux(A,[was,hit],L’).
      • A=aux(was) L’=[hit]
    • ?- transitive(V,[hit],[]).
      • V=v(hit)
  • X=s(np(det(the),n(ball)),vp(aux(was),v(hit)))

s(s(Y,Z)) --> np(Y), vp(Z).

np(np(Y)) --> pronoun(Y).

np(np(D,N)) --> det(D,Number), common_noun(N,Number).

det(det(the),_) --> [the].

det(det(a),sg) --> [a].

common_noun(n(ball),sg) --> [ball].

common_noun(n(man),sg) --> [man].

common_noun(n(men),pl) --> [men].

pronoun(i) --> [i].

pronoun(we) --> [we].

vp(vp(A,V)) --> aux(A), transitive(V).

vp(vp(Y)) --> unergative(Y).

vp(vp(Y,Z)) --> transitive(Y), np(Z).

unergative(v(ran)) --> [ran].

transitive(v(hit)) --> [hit].

aux(aux(was)) --> [was].

passive morphology
Passive Morphology

other morphological rules

(progressive) be V-ing

e.g. was eating

(passive+progressive)

e.g. was being eaten

  • verbal inflection
    • hit eat
    • hits eats (-s)
    • hit ate (-ed)
    • hit eaten (-en)
  • verbal inflection and passive morphology
  • rule: (passive) be V-en
    • was hit (ambiguous between -ed and -en)
    • *was ate (-ed)
    • was eaten (-en)
  • how to implement this restriction?
    • vp(vp(A,V)) --> aux(A), transitive(V).
  • idea
    • use an extra argument to indicate the verb form fortransitive
passive morphology1
Passive Morphology
  • verbal inflection
    • eat (root)
    • eats (-s)
    • ate (-ed)
    • eaten (-en)
  • use an argument to signal the inflected form
  • add rules for eat
    • transitive(v(eat),root) --> [eat].
    • transitive(v(eats),s) --> [eats].
    • transitive(v(ate),ed) --> [ate].
    • transitive(v(eaten),en) --> [eaten].
  • original rule
    • vp(vp(A,V)) --> aux(A), transitive(V).
  • modified rule
    • vp(vp(A,V)) --> aux(A), transitive(V,en).

Constraint for -en realized by Prolog pattern-matching

passive morphology2
Passive Morphology
  • grammar rules (partial)
    • transitive(v(eat),root) --> [eat].
    • transitive(v(eats),s) --> [eats].
    • transitive(v(ate),ed) --> [ate].
    • transitive(v(eaten),en) --> [eaten].
    • vp(vp(A,V)) --> aux(A), transitive(V,en).
    • aux(aux(was)) --> [was].
  • query
    • ?- vp(X,[was,eaten],[]).
  • computation tree
    • ?- vp(X,[was,eaten],[]). X=vp(A,V)
      • ?- aux(A,[was,eaten],L).
      • ?- transitive(V,en,L,[]).
    • ?- aux(A,[was,eaten],L).
      • A=aux(was) L=[eaten]
    • ?- transitive(V,en,[eaten],[]).
      • V=v(eaten)

example: was eaten

passive morphology3

attempted

match fails

Passive Morphology
  • grammar rules (partial)
    • transitive(v(eat),root) --> [eat].
    • transitive(v(eats),s) --> [eats].
    • transitive(v(ate),ed) --> [ate].
    • transitive(v(eaten),en) --> [eaten].
    • vp(vp(A,V)) --> aux(A), transitive(V,en).
    • aux(aux(was)) --> [was].
  • query
    • ?- vp(X,[was,ate],[]).
  • computation tree
    • ?- vp(X,[was,ate],[]). X=vp(A,V)
      • ?- aux(A,[was,ate],L).
      • ?- transitive(V,en,L,[]).
    • ?- aux(A,[was,ate],L).
      • A=aux(was) L=[ate]
    • ?-transitive(V,en,[ate],[]).
      • No

example: *was ate

subject in by phrase

s

s

vp

np

np

vp

aux

v

det

n

det

n

vp

pp

ball

the

was

hit

ball

the

aux

v

p

np

was

hit

by

me

Subject in By-Phrase
  • phrase structure
    • I hit the ball (active)
    • the ball was hit (passive)
    • the ball was hit by me (passive + subject in by-phrase)

optional prepositional phrase (PP)

is adjoined to the verb phrase (VP)

subject in by phrase1

s

np

vp

det

n

vp

pp

ball

the

aux

v

p

np

was

hit

by

me

Subject in By-Phrase
  • phrase structure
    • I hit the ball (active)
    • the ball was hit (passive)
    • the ball was hit by me (passive + subject in by-phrase)
  • add PP rules
    • pp(pp(P,NP)) --> preposition(P), np(NP).
    • preposition(p(by)) --> [by].
  • add VP adjunction rule
    • vp(vp(VP,PP)) --> vp(VP), pp(PP).
  • add pronoun rule
    • np(np(Y)) --> pronoun(Y).
    • pronoun(i) --> [i].
    • pronoun(we) --> [we].
    • pronoun(me) --> [me].
  • there is a Case Constraint
    • (not implemented here)
    • by me
    • *by I
    • *me hit the ball
other constraints

s

vp

np

aux

v

det

n

ball

balls

the

was

were

hit

Other Constraints
  • examples
    • I hit the ball (active)
    • the ball was hit (passive)
    • the ball was hit by me (passive + by-phrase)
    • *the ball were hit by me
    • *the balls was hit by me
    • the balls were hit by me
  • Subject-Verb Agreement Rule
    • subject must agree with the verb for number
    • np(np(D,N)) --> det(D,Number), common_noun(N,Number).
    • common_noun(n(ball),sg) --> [ball].
    • common_noun(n(balls),pl) --> [balls].
  • np(np(D,N),Number) --> det(D,Number), common_noun(N,Number).
other constraints1

s

number

vp

np

number

number

number

aux

v

det

n

ball

balls

the

was

were

hit

Other Constraints
  • examples
    • the ball was hit by me (passive + by-phrase)
    • *the ball were hit by me
    • *the balls was hit by me
    • the balls were hit by me
  • Subject-Verb Agreement Rule
    • subject must agree with the verb for number
    • must propagate number feature up the tree!
    • np(np(D,N),Number) --> det(D,Number),common_noun(N,Number).
    • common_noun(n(ball),sg) --> [ball].
    • common_noun(n(balls),pl) --> [balls].
    • s(s(Y,Z)) --> np(Y,Number), vp(Z).

number

  • s(s(Y,Z)) --> np(Y,Number), vp(Z,Number).
grammar so far
Grammar so far
  • new additions today
    • verbal inflection and passive morphology
      • (passive) be V-en
    • PP by-phrase
      • “by me”
    • Subject-Verb Agreement Rule
      • “the ball/balls was/were”
  • grammar is still not fully specified
    • see underscores “-”

s(s(Y,Z)) --> np(Y,Number), vp(Z,Number).

np(np(Y),_) --> pronoun(Y).

np(np(D,N),Number) --> det(D,Number), common_noun(N,Number).

det(det(the),_) --> [the].

det(det(a),sg) --> [a].

common_noun(n(ball),sg) --> [ball].

common_noun(n(balls),pl) --> [balls].

common_noun(n(man),sg) --> [man].

common_noun(n(men),pl) --> [men].

pronoun(i) --> [i].

pronoun(we) --> [we].

pronoun(me) --> [me].

pp(pp(P,NP)) --> preposition(P), np(NP,_).

preposition(p(by)) --> [by].

vp(vp(VP,PP),_) --> vp(VP,_), pp(PP).

vp(vp(A,V),Number) --> aux(A,Number), transitive(V,en).

vp(vp(Y),_) --> unergative(Y).

vp(vp(Y,Z),_) --> transitive(Y,_), np(Z,_).

unergative(v(ran)) --> [ran].

transitive(v(hit),_) --> [hit].

transitive(v(eat),root) --> [eat].

transitive(v(eats),s) --> [eats].

transitive(v(ate),ed) --> [ate].

transitive(v(eaten),en) --> [eaten].

aux(aux(was),sg) --> [was].

aux(aux(were),pl) --> [were].

grammar so far1
Grammar so far
  • ordering of VP rules is critical

what happens when rule 15 is moved around for the following query?

?- s(X,[the,balls,were,hit,by,me],[]).

  • how to block recursion for *the balls were hit by me by the man?

?- s(X,[the,balls,were,hit,by,me,by,the,man],[]).

  • would ternary branching for VP adjuncts work better computationally?

i.e. vp(vp(A,V,PP)) --> aux(A), transitive(V,en), pp(PP).

s(s(Y,Z)) --> np(Y,Number), vp(Z,Number).

np(np(Y),_) --> pronoun(Y).

np(np(D,N),Number) --> det(D,Number), common_noun(N,Number).

det(det(the),_) --> [the].

det(det(a),sg) --> [a].

common_noun(n(ball),sg) --> [ball].

common_noun(n(balls),pl) --> [balls].

common_noun(n(man),sg) --> [man].

common_noun(n(men),pl) --> [men].

pronoun(i) --> [i].

pronoun(we) --> [we].

pronoun(me) --> [me].

pp(pp(P,NP)) --> preposition(P), np(NP,_).

preposition(p(by)) --> [by].

vp(vp(VP,PP),_) --> vp(VP,_), pp(PP).

vp(vp(A,V),Number) --> aux(A,Number), transitive(V,en).

vp(vp(Y),_) --> unergative(Y).

vp(vp(Y,Z),_) --> transitive(Y,_), np(Z,_).

unergative(v(ran)) --> [ran].

transitive(v(hit),_) --> [hit].

transitive(v(eat),root) --> [eat].

transitive(v(eats),s) --> [eats].

transitive(v(ate),ed) --> [ate].

transitive(v(eaten),en) --> [eaten].

aux(aux(was),sg) --> [was].

aux(aux(were),pl) --> [were].