Natural Language Processing Lectures 8 9 Auxiliary Verbs

Natural Language Processing Lectures 8 -9 Auxiliary Verbs Movement Phenomena Reading: James Allen NLU (Chapter 5) 1

Auxiliary and Modal Verbs • • I can see the house. I will have seen the house. I was watching the movie. I should have been watching the movie. I am not going. He could not have seen the car. I did eat my carrots. Did you see the car? 2

Auxiliary Verbs VP (AUX COMPFORM ? s) (VP VFORM ? s) 3

Auxiliary Verbs (Sequence Constraints) VP (AUX COMPFORM ? s) (VP VFORM ? s) Modal + have + be (Progressive) + be (Passive) They might have been being played as they left. * He has might see the movie already I regret having been chosen to go * I must be having been singing 4

Passive Sentences VP AUX [be] VP [ing, +main] VP AUX [be] VP [ing, +pass] VP [+pass] AUX [be] VP [pastprt, +main] 5

Lexicon Samples 6

Passive Sentences I will hide my hat in the drawer My hat will be hidden in the drawer I hid my hat in the drawer My hat was hidden in the drawer I was hiding my hat in the drawer My hat was being hidden in the drawer 7

Passive sentences • VP constituents in passive sentences have a missing NP • Need a Head binary feature “passgap” VP [-passgap] V [_np] NP VP [+passgap] V [_np] 8

Passive Sentences 9

Rule 1 & 2 & ((7 & 9) or (5 & 8)) 10

Movement phenomena • Local (bounded) movement Subject-aux inversion Jack is giving Sue a book Is Jack giving Sue a book? He will run in the marathon next year Will he run in the marathon next year? John went to the store Did John go to the store? Henry goes to school everyday Does Henry go to school everyday? 11

Movement Phenomena • Unbounded movement wh-questions The fat man will angrily put the book in the corner Which man will angrily put the book in the corner Who will angrily put the book in the corner How will the fat man put the book in the corner In what way will the fat man put the book in the … What will the fat man put angrily in the corner Where will the fat man angrily put the book What will the fat man angrily put the book in 12

Similar to yes/no questions I found a book case Did I find a book case? What did I find? • So we can use part of the grammar for Yes/no questions • But there is a missing constituent What will the fat man angrily put in the corner * I angrily put in the corner 13

Holes and Fillers • There is a Hole somewhere in a constituent • The moved part is a Filler for that hole What will the fat man angrily put in the corner • Is parsed as if it were: … angrily put what in the corner What did you put in the cupboard? * What did you put the bottle in the cupboard 14

Transformational Grammars 15

Filling gaps • Slash categories: are complex non terminals of form X/Y : a constituent of type X with a sub constituent Y missing S/NP S constituent with the GAP feature NP 16

Box 5. 2 Different Types of Movement 17

Questions in CFGs S[+inv] (AUX AGR ? a SUBCAT ? v) (NP AGR ? a) (VP VFORM ? v) (NP GAP (CAT NP AGR ? a) • Inserting GAP Features automatically 1. Lexical Head VP V [_np_vp: inf] NP VP (VP GAP ? g) V [_np_vp: inf] (NP GAP ? g) (VP GAP -) (VP GAP ? g) V [_np_vp: inf] (NP GAP -) (VP GAP ? g) 2. Non Lexical Head (S GAP ? g) (NP GAP -) (VP GAP ? g) 18

Adding Gap features to a grammar 19

Wh-words in Lexicon 20

Wh – words Grammar rules 21

Ws-questions grammar rules 22

Ws-questions grammar rules (expanded) 23

Box 5. 3 Movement Constraints (Island Constraints) • The A over A constraint * What book did you meet the author of __? • Complex-NP constraint * To whom did the man who gave the book __ laugh? • Sentential subject Constraint For me to learn these constraints is impossible. * What is for me to learn __ impossible? • Wh-Island Constraint Did they wonder whether I took the book? * What did they wonder whether I took __? • Coordinate Structure Constraint Did you see John and Sam? * Who did you see and __? 24

Parsing with Gaps (NP GAP (CAT NP AGR ? a) (VP GAP (NP AGR 3 s)) V [_np_pp: loc] (NP GAP (NP AGR 3 s) PP [LOC] (NP AGR 3 s EMPTY +) (VP GAP (NP AGR 3 s)) V [_np_pp: loc] (NP GAP (NP AGR 3 s) PP [LOC] 25

Adding Empty constituents 26

1 Which 2 dogs 3 did 4 he 5 see 6 27

1 Which 2 dogs 3 did 4 he 5 see 6 28

Box 5. 4 Feature Propagation in GPSG Generalized Phrase Structure Grammar Uses Slash feature instead of GAP feature Slash Feature obey two rules : 1. Head Feature principle (all head features are shared between mother constituent and head sub constituent) 2. Foot Feature principle (if a foot feature appears in any sub constituent, it must be shared with mother constituent) Slash feature is both head and foot Uses meta-rules (that only apply to rules with lexical head constituent) to derive additional rules from a basic grammar VP V NP VP/NP V NP [+NULL] VP V[TRANSITIVE] NP X VP [PASSGAP] V X 29

Relative clauses CNP REL (NP WH R AGR ? a) (S[-inv, fin] GAP (NP AGR ? a))) REL (PP WH R PFORM ? p) ( S[-inv, fin] GAP (PP PFORM ? p))) The man who we saw at the store. The exam in which you found the error The man whose book you stole 30

Relative clauses (Cont. ) The man who read the paper (who is the subject) So Need the following rule REL NP [R] VP [fin] The man that we saw at the party The man that read the paper “That” need to regarded as a relative pronoun with WH = R 31

Relative clauses (Cont. ) Relative clauses that do not start with an appropriate wh-phrase: 1. The Paper John read 2. The damage caused by the storm 3. The issue creating the argument 2 and 3 are called Reduced Relative clauses REL (S[fin] GAP (NP AGR ? a))) REL ( VP VFORM {ing, pastprt}) 32

Relative clauses (Cont. ) Can we have Relative clauses within wh_questions? Which dog 1 did the man [who 2 we saw __2 holding the bone] feed __1 ? CNP REL (CNP GAP ? g) (REL GAP -) *Which dog 1 did the man 2 [we saw __2 petting __1 ] laughed? 33