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LING 388: Language and Computers

LING 388: Language and Computers. Sandiway Fong Lecture 12: 10/6. Administrivia. Computer Laboratory Class next Monday (11th October) homework #3 will be handed out meet in SBS 224, Instructional Computing Lab ( not here ). Last Time. Context-Free Grammars (CFG) extra arguments

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LING 388: Language and Computers

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  1. LING 388: Language and Computers Sandiway Fong Lecture 12: 10/6

  2. Administrivia • Computer Laboratory Class • next Monday (11th October) • homework #3 will be handed out • meet in SBS 224, Instructional Computing Lab (not here)

  3. Last Time • Context-Free Grammars (CFG) • extra arguments • used to implement determiner-noun agreement • as well as to hold a parse tree

  4. Today’s Topic • Case study • How to implement the passive construction • verb inflection • constraints between auxiliary and main verbs • subcategorization and adjuncts

  5. Example Grammar • Grammar rules so far including extra arguments for parse tree and 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

  6. Passivization • In English... • 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 verb encoded in the grammar using the transitive non-terminal • I arrived/*I was arrived • unaccusative(v(arrived)) --> [arrived]. • We ran/*We were ran • unergative(v(ran)) --> [ran].

  7. s np vp s v np i det n vp hit the ball aux v np det n was hit the ball Passivization • Phrase Structure: • I hit the ball (active) • the ball was hit (passive) (non-movement account)

  8. s vp aux v np det n was hit the ball 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].

  9. Passivization • 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]. • 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)))

  10. Passive Morphology • Verbal inflection • eat • eats (-s) • ate (-ed) • 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 for transitive Other rules (progressive) be V-ing e.g. was eating

  11. Passive Morphology • Verbal inflection • eat (root) • eats (-s) • ate (-ed) • eaten (-en) • Use an argument to signal the inflected form • 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

  12. Passive Morphology • 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)

  13. Passive Morphology • 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

  14. s vp np aux v vp pp det n was the ball hit np p 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) preposition phrase (pp) is adjoined to the verb phrase (vp)

  15. s vp np aux v vp pp det n was the ball hit np p 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) • PP rules • pp(pp(P,NP)) --> preposition(P), np(NP). • preposition(p(by)) --> [by]. • VP adjunction rule • vp(vp(VP,PP)) --> vp(VP), pp(PP). • Pronoun rule • np(np(Y)) --> pronoun(Y). • pronoun(i) --> [i]. • pronoun(we) --> [we]. • pronoun(me) --> [me]. • Case Constraint (not implemented here) • by me • *by I • *me hit the ball

  16. s vp aux v np det n were hit the balls Other Constraints • Examples: • I hit the ball (active) • the ball was hit (passive) • the ball was hit by me (passive + subject in 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).

  17. s vp aux v np det n were pl hit the balls pl Other Constraints • Examples: • the ball was hit by me (passive + subject in 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),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). • s(s(Y,Z)) --> np(Y,Number), vp(Z,Number).

  18. Next Time • We will practice implementing natural language constraints in the laboratory session • like the morphological case constraint • like the subject-verb agreement constraint

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