1. LING 388: Language and Computers Sandiway Fong Lecture 15 10/13

2. Administrivia Reminder –Homework 5 due next Monday

3. Today’s Topic case study –How to implement the passive construction in a traditional grammar framework verb inflection constraints between auxiliary and main verbs subcategorization and adjuncts

4. 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 only one extra argument for the parse tree verb classes

5. 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].

6. Passivization simple phrase structure –I hit the ball(active) –the ball was hit(passive) A first pass (simplistic non-movement account) s npvp vnp detn the ball hit i s aux vp v np detn the ball hit was avoiding empty categories for simplicity (can be added, see later slide): the ball was hit e [the ball] i was hit t i

7. 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]. s aux vp v np detn the ball hit was

8. Passivization 1.s(s(Y,Z)) --> np(Y), vp(Z). 2.np(np(Y)) --> pronoun(Y). 3.np(np(D,N)) --> det(D,Number), common_noun(N,Number). 4.det(det(the),_) --> [the]. 5.det(det(a),sg) --> [a]. 6.common_noun(n(ball),sg) --> [ball]. 7.common_noun(n(man),sg) --> [man]. 8.common_noun(n(men),pl) --> [men]. 9.pronoun(i) --> [i]. 10.pronoun(we) --> [we]. 11.vp(vp(A,V)) --> aux(A), transitive(V). 12.vp(vp(Y)) --> unergative(Y). 13.vp(vp(Y,Z)) --> transitive(Y), np(Z). 14.unergative(v(ran)) --> [ran]. 15.transitive(v(hit)) --> [hit]. 16.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)))

9. Passivization We are (free to) modify the parse for the VP constituent to include items not found in the input –sometimes this can be very useful –e.g. there are good linguistic reasons why we might prefer to write –vp(vp(Aux,vp(V,np(trace))),Number) --> aux(Aux,Number), transitive(V,Ending), {Ending = en}. instead, which produces: s aux vp v np detn the ball hit was vp np trace

10. Passive Morphology verbal inflection –hiteat –hitseats(-s) –hitate(-ed) –hiteaten(-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 for transitive other morphological rules (progressive) be V-ing e.g. was eating (passive+progressive) e.g. was being eaten

11. Passive Morphology verbal inflection –eat(root) –eats(-s) –ate(-ed) –eaten(-en) use an extra argument to signal the inflected form, e.g. –transitive(v(eat),root) --> [eat]. –transitive(v(eat-s),s) --> [eats]. –transitive(v(eat-ing),ing) --> [eating]. –transitive(v(eat-ed),ed) --> [ate]. –transitive(v(eat-en),en) --> [eaten]. original rule –vp(vp(A,V)) --> aux(A), transitive(V). modified rule –vp(vp(A,V)) --> aux(A), transitive(V,en). equivalently vp(vp(A,V)) --> aux(A), transitive(V,Ending),{Ending=en}. Constraint for -en realized by Prolog pattern-matching

12. 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

13. 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 attempted match fails

14. 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) s aux vp v np detn the ball hit was vppp p np byme s aux vp v np detn the ball hit was

15. 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 s aux vp v np detn the ball hit was vppp p np byme

16. 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). s aux vp v np detn the ball balls hit was were

17. 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). –s(s(Y,Z)) --> np(Y,Number), vp(Z,Number). s aux vp v np detn the ball balls hit was were number

18. 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 implemented –see underscores “-” for Subject-Verb Agreement 1.s(s(Y,Z)) --> np(Y,Number), vp(Z,Number). 2.np(np(Y),_) --> pronoun(Y). 3.np(np(D,N),Number) --> det(D,Number), common_noun(N,Number). 4.det(det(the),_) --> [the]. 5.det(det(a),sg) --> [a]. 6.common_noun(n(ball),sg) --> [ball]. 7.common_noun(n(balls),pl) --> [balls]. 8.common_noun(n(man),sg) --> [man]. 9.common_noun(n(men),pl) --> [men]. 10.pronoun(i) --> [i]. 11.pronoun(we) --> [we]. 12.pronoun(me) --> [me]. 13.pp(pp(P,NP)) --> preposition(P), np(NP,_). 14.preposition(p(by)) --> [by]. 15.vp(vp(VP,PP),_) --> vp(VP,_), pp(PP). 16.vp(vp(A,V),Number) --> aux(A,Number), transitive(V,en). 17.vp(vp(Y),_) --> unergative(Y). 18.vp(vp(Y,Z),_) --> transitive(Y,_), np(Z,_). 19.unergative(v(ran)) --> [ran]. 20.transitive(v(hit),_) --> [hit]. 21.transitive(v(eat),root) --> [eat]. 22.transitive(v(eats),s) --> [eats]. 23.transitive(v(ate),ed) --> [ate]. 24.transitive(v(eaten),en) --> [eaten]. 25.aux(aux(was),sg) --> [was]. 26.aux(aux(were),pl) --> [were].

19. Grammar built in class: Part 1 s(s(Y,Z)) --> np(Y,Num1), vp(Z,Num2), {Num1 = Num2}. % Partial Subject-Verb agreement np(np(Y),Number) --> pronoun(Y,Number). np(np(D,N),Number) --> det(D,Number), common_noun(N,Number). det(det(the),_) --> [the]. det(det(a),sg) --> [a]. common_noun(n(apple),sg) --> [apple]. common_noun(n(ball),sg) --> [ball]. common_noun(n(man),sg) --> [man]. common_noun(n(men),pl) --> [men]. pronoun(i,sg) --> [i]. pronoun(we,pl) --> [we]. pronoun(me,sg) --> [me]. vp(vp(Y),_) --> unergative(Y). vp(vp(Y,Z),_) --> transitive(Y,_), np(Z,_). vp(vp(Aux,vp(V,np(trace))),Number) --> aux(Aux,Number), transitive(V,Ending), {Ending = en}. vp(vp(VP,NP),Number) --> vp(VP,Number), pp(NP).

20. Grammar built in class: Part 2 unergative(v(ran)) --> [ran]. transitive(v(hit),root) --> [hit]. transitive(v(hit-s),s) --> [hits]. transitive(v(hit-ing),ing) --> [hitting]. transitive(v(hit-ed),ed) --> [hit]. transitive(v(hit-en),en) --> [hit]. transitive(v(eat),root) --> [eat]. transitive(v(eat-ing),ing) --> [eating]. transitive(v(eat-s),s) --> [eats]. transitive(v(eat-ed),ed) --> [ate]. transitive(v(eat-en),en) --> [eaten]. aux(aux(was),sg) --> [was]. aux(aux(was),pl) --> [were]. pp(pp(P,NP)) --> p(P), np(NP,_). p(p(by)) --> [by].

21. Outstanding issues The relative order of the VP rules is critical e.g. what happens when the rule vp(vp(VP,PP),Number) --> vp(VP,Number), pp(PP). is moved around in the program for the following query? ?- s(X,[the,balls,were,hit,by,me],[]). how to block recursion (iteration) for *the balls were hit by me by the man? ?- s(X,[the,balls,were,hit,by,me,by,the,man],[]). would (less linguistically desirable) ternary branching for the VP adjunct work better computationally? e.g. vp(vp(A,V,PP)) --> aux(A), transitive(V,en), pp(PP).

22. More to come… Grammar also has infinite loops, i.e. does not terminate properly We’ll fix these issues next time