LING 388: Language and Computers

1
LING 388 Language and Computers

• Sandiway Fong
• Lecture 13 10/11

2
Administrivia

• Computer Laboratory Class
• homework 3 to be handed out
• due next Monday (18th October)
• email sandiway_at_email.arizona.edu (by midnight)
• Homework 2
• handed back today
• or available in the yellow folder in my mailbox
  in Linguistics (Douglass building)
• Next Time
• back in Harvill

3
Last Time

• Case study
• How to implement the passive construction
• verb inflection
• constraints between auxiliary and main verbs
• subcategorization and adjuncts

4
Todays Topic

• Well take the grammar weve been developing so
  far and explore adding more constraints

5
Example Grammar

• s(s(Y,Z)) --gt np(Y), vp(Z).
• np(np(Y)) --gt pronoun(Y).
• np(np(D,N)) --gt det(D,Number), common_noun(N,Numbe
  r).
• det(det(the),_) --gt the.
• det(det(a),sg) --gt a.
• common_noun(n(ball),sg) --gt ball.
• common_noun(n(man),sg) --gt man.
• common_noun(n(men),pl) --gt men.
• pronoun(i) --gt i.
• pronoun(we) --gt we.
• pronoun(me) --gt me.
• vp(vp(Y)) --gt unergative(Y).
• vp(vp(Y,Z)) --gt transitive(Y,_), np(Z).
• vp(vp(A,V)) --gt aux(A), transitive(V,en).
• vp(vp(VP,PP)) --gt vp(VP), pp(PP).
• pp(pp(P,NP)) --gt preposition(P), np(NP).
• preposition(p(by)) --gt by.
• unergative(v(ran)) --gt ran.
• transitive(v(hit),_) --gt hit.

• Grammar weve been developing so far includes
  passivization and extra arguments for
• parse tree
• determiner-noun agreement
• passive morphology

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Exercise 1 Passivization

• Load grammar shown on previous slide into
  SWI-Prolog
• cut-and-paste directly into a text file
• also available as file named g13.pl from course
  homepage
• http//dingo.sbs.arizona.edu/sandiway/ling388n/

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Exercise 1 Passivization

• Verify the following sentences are parsed by the
  grammar
• I hit the ball (active)
• the ball was hit (passive)
• the ball was hit by me (passive subject in
  by-phrase)
• Query
• ?- s(X,Sentence,).
• Warning do not hit for more answers, just the
  return key

(non-movement account)
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Exercise 1 Passivization

• Homework Question (6pts)
• Add the grammar rules necessary to parse the
  following sentences
• the apple was eaten (passive)
• the apple was eaten by the worm (passive
  by-phrase)
• john burned the toast
• the toast was burnt by john
• Submit both the rules and the output
• Notes
• you will need to write a NP rule for proper nouns
  like john
• use lowercase john (for simplicity in the lexical
  rule)

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Exercise 2 Left Recursion and the By-Phrase

• Phrase Structure
• the ball was hit by me (passive subject in
  by-phrase)
• PP rules
• pp(pp(P,NP)) --gt preposition(P), np(NP).
• preposition(p(by)) --gt by.
• VP adjunction rule
• vp(vp(VP,PP)) --gt vp(VP), pp(PP).
• this rule is left-recursive
• unfortunately it makes the parser loop
• on all sentences (not just passive ones
• with a by-phrase)
• Hence the warning in Exercise 1...
• Warning do not hit for more answers, just the
  return key

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Exercise 2 Left Recursion and the By-Phrase

• How do we verify that this rule causes the
  grammar to loop?
• Run following sentence and hit for more answers
• I hit the ball
• Output
• ?- s(X,i,hit,the,ball,).
• X s(np(i), vp(v(hit), np(det(the), n(ball))))
• ERROR Out of local stack

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Exercise 2 Left Recursion and the By-Phrase

• How do we verify that this rule causes the
  grammar to loop?
• Remove the rule from the grammar
• Hint comment it out using Prologs comment
  character
• ...
• vp(vp(Y,Z)) --gt transitive(Y,_), np(Z).
• vp(vp(A,V)) --gt aux(A), transitive(V,en).
• vp(vp(VP,PP)) --gt vp(VP), pp(PP).
• pp(pp(P,NP)) --gt preposition(P), np(NP).
• ...
• 2. Re-load the grammar and re-run the sentence I
  hit the ball
• See the difference in behavior when you hit for
  more answers
• Output
• ?- s(X,i,hit,the,ball,).
• X s(np(i), vp(v(hit), np(det(the), n(ball))))
• No

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Exercise 2 Left Recursion and the By-Phrase

• How do we verify that this rule causes the
  grammar to loop?
• Lets trace the parser and look at how this works
• Uncomment rule, i.e. put it back into the grammar
• Hint remove the comment character
• Re-load the grammar and turn on tracing
• ?- trace.
• Step through sentence I hit the ball
• Pay special attention to what happens after you
  hit for more answers
• Output
• ?- s(X,i,hit,the,ball,).
• X s(np(i), vp(v(hit), np(det(the), n(ball))))

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Exercise 2 Left Recursion and the By-Phrase

• Output
• trace ?- s(X,i,hit,the,ball,).
• Call (7) s(_G295, i, hit, the, ball, ) ?
  creep
• Call (8) np(_G359, i, hit, the, ball,
  _G368) ? skip
• Exit (8) np(np(i), i, hit, the, ball, hit,
  the, ball) ? creep
• Call (8) vp(_G360, hit, the, ball, ) ?
  creep
• Call (9) unergative(_G364, hit, the, ball,
  ) ? skip
• Fail (9) unergative(_G364, hit, the, ball,
  ) ? creep
• Redo (8) vp(_G360, hit, the, ball, ) ?
  creep
• Call (9) transitive(_G364, _G372, hit, the,
  ball, _G374) ? skip
• Exit (9) transitive(v(hit), _G374, hit, the,
  ball, the, ball) ? creep
• Call (9) np(_G365, the, ball, ) ? skip
• Exit (9) np(np(det(the), n(ball)), the,
  ball, ) ? creep
• Exit (8) vp(vp(v(hit), np(det(the),
  n(ball))), hit, the, ball, ) ? creep
• Exit (7) s(s(np(i), vp(v(hit), np(det(the),
  n(ball)))), i, hit, the, ball, ) ? creep
• X s(np(i), vp(v(hit), np(det(the), n(ball))))

creep return skip s
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Exercise 2 Left Recursion and the By-Phrase
vp(vp(Y,Z)) --gt transitive(Y,_),
np(Z). vp(vp(A,V)) --gt aux(A), transitive(V,en). v
p(vp(VP,PP)) --gt vp(VP), pp(PP).

• Output
• X s(np(i), vp(v(hit), np(det(the), n(ball))))
• Redo (10) common_noun(_G370, _G379, ball,
  ) ? skip
• Fail (10) common_noun(_G370, _G379, ball,
  ) ? skip
• Fail (10) det(_G369, _G377, the, ball,
  _G379) ? skip
• Fail (9) np(_G365, the, ball, ) ? skip
• Fail (9) transitive(_G364, _G372, hit, the,
  ball, _G374) ? skip
• Redo (8) vp(_G360, hit, the, ball, ) ?
  creep
• Call (9) aux(_G364, hit, the, ball, _G373)
  ? skip
• Fail (9) aux(_G364, hit, the, ball, _G373)
  ? creep
• Redo (8) vp(_G360, hit, the, ball, ) ?
  creep
• Call (9) vp(_G364, hit, the, ball, _G373) ?
  skip
• Exit (9) vp(vp(v(hit), np(det(the),
  n(ball))), hit, the, ball, ) ? creep
• Call (9) pp(_G365, , ) ? skip
• Fail (9) pp(_G365, , ) ? creep

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Exercise 2 Left Recursion and the By-Phrase
vp(vp(Y,Z)) --gt transitive(Y,_),
np(Z). vp(vp(A,V)) --gt aux(A), transitive(V,en). v
p(vp(VP,PP)) --gt vp(VP), pp(PP).

• Output
• Redo (11) common_noun(_G373, _G382, ball,
  _G384) ? skip
• Fail (11) common_noun(_G373, _G382, ball,
  _G384) ? skip
• Fail (11) det(_G372, _G380, the, ball,
  _G382) ? skip
• Fail (10) np(_G368, the, ball, _G378) ?
  skip
• Fail (10) transitive(_G367, _G375, hit, the,
  ball, _G377) ? skip
• Redo (9) vp(_G364, hit, the, ball, _G373) ?
  creep
• Call (10) aux(_G367, hit, the, ball, _G376)
  ? skip
• Fail (10) aux(_G367, hit, the, ball, _G376)
  ? creep
• Redo (9) vp(_G364, hit, the, ball, _G373) ?
  creep
• Call (10) vp(_G367, hit, the, ball, _G376)
  ? skip
• Exit (10) vp(vp(v(hit), np(det(the),
  n(ball))), hit, the, ball, ) ? creep
• Call (10) pp(_G368, , _G388) ?

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Exercise 2 Left Recursion and the By-Phrase

• Homework Question (4pts)
• Explain in your own words step-by-step why the
  Prolog computation rule successfully parses the
  sentence
• the ball was hit by me
• but then goes into an infinite loop when asked
  for more answers
• Submit your prose and both the trace and your
  output highlighting where the parser loops
• Extra Credit Homework Question (5pts)
• Suggest how we can fix the problem
• give a concrete suggestion
• i.e. dont just simply say eliminate the left
  recursion
• If you can, implement your suggestion and submit
  the grammar and output

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Exercise 3 Subject-Verb Agreement

• From last lecture ...
• Examples
• I hit the ball (active)
• the ball was hit (passive)
• the ball were hit
• the balls was hit
• the balls were hit
• Subject-Verb Agreement Rule
• subject must agree with the verb for number

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Exercise 3 Subject-Verb Agreement

• Examples
• I hit the ball (active)
• the ball was hit (passive)
• the ball were hit
• the balls was hit
• the balls were hit
• Step 1 Implement was/were
• vp(vp(A,V)) --gt aux(A), transitive(V,en).
• aux(aux(was)) --gt was.
• aux(aux(were)) --gt were.

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Exercise 3 Subject-Verb Agreement

• Examples
• I hit the ball (active)
• the ball was hit (passive)
• the ball were hit
• the balls was hit
• the balls were hit
• Step 2 Implement the number feature for was/were
• vp(vp(A,V)) --gt aux(A,Number), transitive(V,en).
• aux(aux(was),sg) --gt was.
• aux(aux(were),pl) --gt were.

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Exercise 3 Subject-Verb Agreement

• Examples
• I hit the ball (active)
• the ball was hit (passive)
• the ball were hit
• the balls was hit
• the balls were hit
• Step 3 Propagate the number feature up to the
  rule where the verb phrase meets the subject (for
  subject-verb agreement)
• s(s(Y,Z)) --gt np(Y), vp(Z,Number).
• vp(vp(A,V),Number) --gt aux(A,Number),
  transitive(V,en).

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Exercise 3 Subject-Verb Agreement

• Examples
• I hit the ball (active)
• the ball was hit (passive)
• the ball were hit
• the balls was hit
• the balls were hit
• Step 4 Subject noun phrase (NP) must agree with
  the Number value for the verb phrase (VP)
• Add the number feature for NP and propagate this
  down to ball/balls
• s(s(Y,Z)) --gt np(Y,Number), vp(Z,Number).
• vp(vp(A,V),Number) --gt aux(A,Number),
  transitive(V,en).
• np(np(D,N),Number) --gt det(D,Number),
  common_noun(N,Number).
• det(det(the),_) --gt the.
• det(det(a),sg) --gt a.
• common_noun(n(ball),sg) --gt ball.
• common_noun(n(balls),pl) --gt balls.

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Exercise 3 Subject-Verb Agreement

• Examples
• I hit the ball (active)
• the ball was hit (passive)
• the ball were hit
• the balls was hit
• the balls were hit
• Step 5 Add the number feature for all types of
  NPs
• np(np(D,N),Number) --gt det(D,Number),
  common_noun(N,Number).
• np(np(Y),Number) --gt pronoun(Y,Number).
• pronoun(i,sg) --gt i.
• pronoun(we,pl) --gt we.
• pronoun(me,sg) --gt me.

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Exercise 3 Subject-Verb Agreement

• Verify that the following examples can be parsed
  now
• Examples
• the ball was hit
• the ball were hit
• the balls was hit
• the balls were hit
• Output
• ?- s(X,the,balls,were,hit,).
• X s(np(det(the), n(balls)), vp(aux(were),
  v(hit)))
• Yes
• ?- s(X,the,balls,was,hit,).
• No
• ?- s(X,the,ball,were,hit,).
• No
• ?- s(X,the,ball,was,hit,).
• X s(np(det(the), n(ball)), vp(aux(was),
  v(hit)))
• Yes

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Exercise 3 Subject-Verb Agreement

• Homework Question (4pts)
• Examples
• I hit the ball (active)
• the ball was hit (passive)
• the ball were hit
• the balls was hit
• the balls were hit
• The active example sentence now no longer works
• ?- s(X,i,hit,the,ball,).
• No
• Why? Fix the grammar.
• Submit both your grammar and the output

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Exercise 4 Morphological Case

• Examples
• I hit the ball
• me hit the ball
• the ball hit me
• the ball hit I
• the ball was hit by me
• the ball was hit by I
• First person pronouns in English inflect for
  morphological case endings
• I nominative
• me accusative
• we nominative
• us accusative

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Exercise 4 Morphological Case

• Examples
• I hit the ball
• me hit the ball
• the ball hit me
• the ball hit I
• the ball was hit by me
• the ball was hit by I
• Use original grammar g13.pl (back at the
  beginning of this class)
• Add an extra parameter to specify case
• Rules
• np(np(Y),Case) --gt pronoun(Y,Case).
• pronoun(i,nom) --gt i.
• pronoun(we,nom) --gt we.
• pronoun(me,acc) --gt me.

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Exercise 4 Morphological Case

• Examples
• I hit the ball
• me hit the ball
• the ball hit me
• the ball hit I
• the ball was hit by me
• the ball was hit by I
• Case constraint
• subjects must have nominative case
• Rule
• s(s(Y,Z)) --gt np(Y,nom), vp(Z).
• Verify the first two example sentences work
• ?- s(X,i,hit,the,ball,).
• X s(np(i), vp(v(hit), np(det(the), n(ball))))
• ?- s(X,me,hit,the,ball,).
• No

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Exercise 4 Morphological Case

• Examples
• I hit the ball
• me hit the ball
• the ball hit me
• the ball hit I
• the ball was hit by me
• the ball was hit by I
• Homework Question (6pts)
• Implement the constraints necessary to handle the
  remaining four example sentences
• Submit both your grammar and the output

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Homework Summary

• Homework
• Question 1 (6pts)
• Question 2 (4pts)
• Question 3 (4pts)
• Question 4 (6pts)
• Total 20 pts
• Extra Credit
• Question 2 (5pts)