LING 388: Language and Computers

Sandiway FongLecture 22

Review of g21.pl

• g21.pl is the latest English grammar we've developed so far …

g21.pl

g21.pl

g21.pl

g21.pl

All subject NPs have a nom Case constraint

g21.pl

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g21.plAll VP object NPs have an acc Case constraint

g21.pl

PP object NPs also have an acc Case constraint

g21.pl

New Topic

• Let’s write a grammar for simple Japanese

Japanese• head-final language

– sentence word order (canonical)• Subject Object Verb (Japanese)• Subject Verb Object (English)

• example– John bought a book (English)– John a book bought (Japanese word order)– Taroo-ga hon-o kaimashita (Japanese)– case markers

• ga = nominative case marker• o = accusative case marker

– note: no determiner present in the Japanese sentence

Japanese

• head-final language– sentence word order

(canonical)• Subject Object Verb

– Japanese also allows “scrambling”• e.g. object and subject can

be switched in order• Subject Object Verb• Object Subject Verb• *Subject Verb Object

(must still be head-final)

• Example– John bought a book (English)– John a book bought– Taroo-ga hon-o kaimashita

(Japanese - canonical)– hon-o Taroo-ga kaimashita

(Japanese - scrambled)

– *Taroo-ga kaimashita hon-o(English

word order)

– ga = nominative case marker– o = accusative case marker

Japaneseexample• John bought a book• John a book bought• taroo-ga hon-o kaimashita

• ga = nominative • case marker• o = accusative • case marker

• Parser input – (as a Prolog list with case particles separated)– [taroo,ga,hon,o,kaimashita]

• Example grammar ruless(s(Y,Z)) --> np(Y), nomcase, vp(Z).vp(vp(Z,Y)) --> np(Z), acccase, transitive(Y).transitive(v(kaimashita)) --> [kaimashita].nomcase --> [ga].acccase --> [o].np(np(taroo)) --> [taroo].np(np(hon)) --> [hon].

note:• new nonterminals nomcase acccase do not create structure• order of np, transitive in the VP reflects Japanese word order

Japanese• example

– John a book bought– taroo-ga hon-o kaimashita– ga = nominative case marker– o = accusative case marker

• computation tree– ?- s(X,[taroo,ga,hon,o,kaimashita],[]).

• ?- np(Y,[taroo,ga,hon,o,kaimashita],L1).• ?- nomcase(L1,L2).• ?- vp(Z,L2,[]).

– ?- np(Y,[taroo,ga,hon,o,kaimashita],L1).• Y = np(taroo) L1 = [ga,hon,o,kaimashita]

– ?- nomcase([ga,hon,o,kaimashita],L2).• L2 = [hon,o,kaimashita]

– ?- vp(vp(Z’,Y’), [hon,o,kaimashita],[]). Z = vp(Z’,Y’)• ?- np(Z’,[hon,o,kaimashita],L1’).• ?- acccase(L1’,L2’).• ?- transitive(Y’,L2’,[]).

1. s(s(Y,Z)) --> np(Y), nomcase, vp(Z).2. vp(vp(Z,Y)) --> np(Z), acccase,

transitive(Y).3. transitive(v(kaimashita)) --> [kaimashita].4. nomcase --> [ga].5. acccase --> [o].6. np(np(taroo)) --> [taroo].7. np(np(hon)) --> [hon].

Japanese• example

– John a book bought– taroo-ga hon-o kaimashita– ga = nominative case marker– o = accusative case marker

• computation tree– ?- vp(vp(Z’,Y’), [hon,o,kaimashita],[]).

• ?- np(Z’,[hon,o,kaimashita],L1’).• ?- acccase(L1’,L2’).• ?- transitive(Y’,L2’,[]).

– ?- np(Z’,[hon,o,kaimashita],L1’)• Z’ = np(hon) L1’ = [o,kaimashita]

– ?- acccase([o,kaimashita],L2’).• L2’ = [kaimashita]

– ?- transitive(Y’,[kaimashita],[]).• Y’ = v(kaimashita)

• answer– ?- s(X,[taroo,ga,hon,o,kaimashita],[]).– X = s(np(taroo), vp(np(hon), v(kaimashita)))

1. s(s(Y,Z)) --> np(Y), nomcase, vp(Z).2. vp(vp(Z,Y)) --> np(Z), acccase,

transitive(Y).3. transitive(v(kaimashita)) --> [kaimashita].4. nomcase --> [ga].5. acccase --> [o].6. np(np(taroo)) --> [taroo].7. np(np(hon)) --> [hon].

Japanese

• exampleJohn a book boughttaroo-ga hon-o kaimashitaga = nominative case markero = accusative case marker

• grammar– can be run “backwards” for sentence generation– we’ll need this

• query– ?- s(s(np(taroo), vp(np(hon), v(kaimashita))),L,[]).– L = [taroo, ga, hon, o, kaimashita]

GeneratorSentence Parse tree

ParserSentence Parse tree

1. s(s(Y,Z)) --> np(Y), nomcase, vp(Z).2. vp(vp(Z,Y)) --> np(Z), acccase,

transitive(Y).3. transitive(v(kaimashita)) --> [kaimashita].4. nomcase --> [ga].5. acccase --> [o].6. np(np(taroo)) --> [taroo].7. np(np(hon)) --> [hon].

Japanese

• exampleJohn a book boughttaroo-ga hon-o kaimashita

• query (generation)– ?- s(s(np(taroo),vp(np(hon),v(kaimashita))),L,[]).

• Y = np(taroo) Z = vp(np(hon),v(kaimashita)))• ?- np(np(taroo),L,L1).• ?- nomcase(L1,L2).• ?- vp(vp(np(hon),v(kaimashita))),L2,[]).

– ?- np(np(taroo),L,L1).• L = [taroo|L1]

– ?- nomcase(L1,L2).• L1 = [ga|L2]

– ?- vp(vp(np(hon),v(kaimashita))),L2,[]).• Z’ = np(hon) Y’ = v(kaimashita)• ?- np(np(hon),L2,L3).• ?- acccase(L3,L4).• ?- transitive(v(kaimashita),L4,[]).

1. s(s(Y,Z)) --> np(Y), nomcase, vp(Z).2. vp(vp(Z,Y)) --> np(Z), acccase,

transitive(Y).3. transitive(v(kaimashita)) --> [kaimashita].4. nomcase --> [ga].5. acccase --> [o].6. np(np(taroo)) --> [taroo].7. np(np(hon)) --> [hon].

Japanese

• example– John a book bought– taroo-ga hon-o kaimashita

• query (generation)– ?- vp(vp(np(hon),v(kaimashita))),L2,[]).

• Z’ = np(taroo) Y’ = v(kaimashita)• ?- np(np(hon),L2,L3).• ?- acccase(L3,L4).• ?- transitive(v(kaimashita),L4,[]).

– ?- np(np(hon),L2,L3).• L2 = [hon|L3]

– ?- acccase(L3,L4).• L3 = [o|L4]

– ?- transitive(v(kaimashita),L4,[]).• L4 = [kaimashita|[]]

1. s(s(Y,Z)) --> np(Y), nomcase, vp(Z).2. vp(vp(Z,Y)) --> np(Z), acccase,

transitive(Y).3. transitive(v(kaimashita)) --> [kaimashita].4. nomcase --> [ga].5. acccase --> [o].6. np(np(taroo)) --> [taroo].7. np(np(hon)) --> [hon].

Japanese

• example– John a book bought– taroo-ga hon-o kaimashita

• query (generation)– back-substituting ...– ?- np(np(taroo),L,L1).

• L = [taroo|L1]

– ?- nomcase(L1,L2).• L1 = [ga|L2]

– ?- np(np(hon),L2,L3).• L2 = [hon|L3]

– ?- acccase(L3,L4).• L3 = [o|L4]

– ?- transitive(v(kaimashita),L4,[]).• L4 = [kaimashita|[]]

• answer– L = [taroo, ga, hon, o, kaimashita]

1. s(s(Y,Z)) --> np(Y), nomcase, vp(Z).2. vp(vp(Z,Y)) --> np(Z), acccase,

transitive(Y).3. transitive(v(kaimashita)) --> [kaimashita].4. nomcase --> [ga].5. acccase --> [o].6. np(np(taroo)) --> [taroo].7. np(np(hon)) --> [hon].

Scrambling

• Idea:– object moves (i.e. “scrambled”) to the front of the sentence– leaves a trace behind in canonical object position– adjoins to S

• Implementation:

Scrambling

• Result:

Japanese• wh-NP phrases

– English– examples

• John bought a book• Who bought a book? (subject wh-phrase)• *John bought what? (echo-question only)• What did John buy? (object wh-phrase)

• object wh-phrase case– complex operation required from the declarative form:

» object wh-phrase must be fronted» do-support (insertion of past tense form of “do”)» bought buy (untensed form)

John bought a bookJohn bought whatwhat John boughtwhat did John boughtwhat did John buy

Japanese• wh-NP phrases

– English• Who bought a book? (subject wh-phrase)• *John bought what? (only possible as an echo-question)• What did John buy? (object wh-phrase)

– Japanese• wh-in-situ:

– meaning wh-phrase appears in same position as a regular noun phrase– easy to implement! (no complex series of operations)

• taroo-ga nani-o kaimashita ka– nani: means what– ka: sentence-final question particle

• dare-ga hon-o kaimashita ka– dare: means who

register differences:ka or no?

Japanese• wh-in-situ:

– taroo-ga nani-o kaimashita ka• nani: means what• ka: sentence-final question particle

– dare-ga hon-o kaimashita ka• dare: means who

• grammar– s(s(Y,Z)) --> np(Y), nomcase, vp(Z).– vp(vp(Z,Y)) --> np(Z), acccase, transitive(Y).– transitive(v(kaimashita)) --> [kaimashita].– nomcase --> [ga].– acccase --> [o].– np(np(taroo)) --> [taroo].– np(np(hon)) --> [hon].

• add new wh-words– np(np(dare)) --> [dare].– np(np(nani)) --> [nani].

Japanese• wh-in-situ:

– taroo-ga nani-o kaimashita ka– dare-ga hon-o kaimashita ka

• grammar– s(s(Y,Z)) --> np(Y), nomcase, vp(Z).– vp(vp(Z,Y)) --> np(Z), acccase, transitive(Y).– transitive(v(kaimashita)) --> [kaimashita].– nomcase --> [ga].– acccase --> [o].– np(np(taroo)) --> [taroo].– np(np(hon)) --> [hon].– np(np(dare)) --> [dare].– np(np(nani)) --> [nani].

• allows sentences– Taroo-ga hon-o kaimashita– Taroo-ga nani-o kaimashita (ka)– dare-ga hon-o kaimashita (ka)

Assuming for simplicity that a sentence-final particle is required for wh-questions…

How to enforce the constraint that ka is obligatory when a wh-phrase is in the sentence?

Japanese• wh-in-situ:

– taroo-ga nani-o kaimashita ka– dare-ga hon-o kaimashita ka

• grammar– s(s(Y,Z)) --> np(Y,Q), nomcase, vp(Z).– vp(vp(Z,Y)) --> np(Z,Q), acccase, transitive(Y).– transitive(v(kaimashita)) --> [kaimashita].– nomcase --> [ga].– acccase --> [o].– np(np(taroo),notwh) --> [taroo].– np(np(hon),notwh) --> [hon].– np(np(dare),wh) --> [dare].– np(np(nani),wh) --> [nani].

• answer– employ extra argument to encode the lexical feature wh (e.g with values wh,

notwh) for nouns

Japanese• wh-in-situ:

– taroo-ga nani-o kaimashita ka– dare-ga hon-o kaimashita ka

• grammar– s(s(Y,Z)) --> np(Y,Q1), nomcase, vp(Z,Q2).– vp(vp(Z,Y),Q) --> np(Z,Q), acccase, transitive(Y).– transitive(v(kaimashita)) --> [kaimashita].– nomcase --> [ga].– acccase --> [o].– np(np(taroo),notwh) --> [taroo].– np(np(hon),notwh) --> [hon].– np(np(dare),wh) --> [dare].– np(np(nani),wh) --> [nani].

• answer– employ an extra argument to encode the lexical feature wh for nouns– propagate this feature up to the (top) sentence rule

• means adding extra argument Q to the VP nonterminal

Japanese• wh-in-situ:

– taroo-ga nani-o kaimashita ka– dare-ga hon-o kaimashita ka

• grammar– s(s(Y,Z)) --> np(Y,Q1), nomcase, vp(Z,Q2), sf(Q1,Q2).– vp(vp(Z,Y),Q) --> np(Z,Q), acccase, transitive(Y).– transitive(v(kaimashita)) --> [kaimashita].– nomcase --> [ga].– acccase --> [o].– np(np(taroo),notwh) --> [taroo].– np(np(hon),notwh) --> [hon].– np(np(dare),wh) --> [dare].– np(np(nani),wh) --> [nani].

• answer– employ an extra argument to encode the lexical feature wh for nouns– propagate this feature up to the (top) sentence rule

• means adding extra argument Q to the VP nonterminal– add a sentence-final particle rule (sf) that generates ka when this

feature is wh

Japanese• wh-in-situ:

– taroo-ga nani-o kaimashita ka– dare-ga hon-o kaimashita ka

• grammar– s(s(Y,Z)) --> np(Y,Q1), nomcase, vp(Z,Q2), sf(Q1,Q2).– vp(vp(Z,Y),Q) --> np(Z,Q), acccase, transitive(Y).– transitive(v(kaimashita)) --> [kaimashita].– nomcase --> [ga].– acccase --> [o].– np(np(taroo),notwh) --> [taroo].– np(np(hon),notwh) --> [hon].– np(np(dare),wh) --> [dare].– np(np(nani),wh) --> [nani].

• answer– employ an extra argument to encode the lexical feature wh for nouns– propagate this feature up to the (top) sentence rule

• means adding extra argument Q to the VP nonterminal– add a sentence-final particle rule (sf) that generates ka when this

feature is wh

sentence-final particle rule (sf/2)sf(wh,notwh) --> [ka].sf(notwh,wh) --> [ka].sf(notwh,notwh) --> []. (empty)sf(wh,wh) --> [ka].

sf(wh,wh) --> [ka].example: dare-ga nani-o kaimashita ka (who bought what)

Japanese• wh-in-situ:

– taroo-ga nani-o kaimashita ka– dare-ga hon-o kaimashita ka

• computation tree– ?- s(X,[taroo,ga,nani,o,kaimashita,ka],[]).– X = s(np(taroo),vp(np(nani),v(kaimashita))) – ?- s(X,[taroo,ga,nani,o,kaimashita],[]).– false

s(s(Y,Z)) --> np(Y,Q1), nomcase, vp(Z,Q2), sf(Q1,Q2).vp(vp(Z,Y),Q) --> np(Z,Q), acccase, transitive(Y).transitive(v(kaimashita)) --> [kaimashita].nomcase --> [ga].acccase --> [o].np(np(taroo),notwh) --> [taroo].np(np(hon),notwh) --> [hon].np(np(dare),wh) --> [dare].np(np(nani),wh) --> [nani]. sf(wh,notwh) --> [ka].sf(notwh,wh) --> [ka].sf(notwh,notwh) --> [].sf(wh,wh) --> [ka].

we may want to modifiy the parse tree to represent the sentence-final particle ka as well

AppendixAlternative implementations…• so far, we used:

– s(s(Y,Z)) --> np(Y,Q1), nomcase, vp(Z,Q2), sf(Q1,Q2).

• could have written (equivalently)– s(s(Y,Z)) --> np(Y,notwh), nomcase, vp(Z,notwh).– s(s(Y,Z)) --> np(Y,Q1), nomcase, vp(Z,Q2), {\+ Q1=notwh ; \+

Q2=notwh }, sf.– sf --> [ka].

• or (also equivalently)– s(s(Y,Z)) --> np(Y,notwh), nomcase, vp(Z,notwh).– s(s(Y,Z,ka)) --> np(Y,Q1), nomcase, vp(Z,Q2), {\+ Q1=notwh ; \+

Q2=notwh }, sf.– sf --> [ka].

– generates different structures for declarative vs. wh-NP questions