Grammar Writing Lecture 5

1. Grammar WritingLecture 5 11-721 Grammars and Lexicons Teruko Mitamura teruko@cs.cmu.edu www.cs.cmu.edu/~teruko LTI Grammars and Lexicons

2. Schedule: November 19, 2007 • Review of “bird.gra” • Review of “bird2.gra” • Character-based Parsing vs. Word-based Parsing • Morphology • Start a new grammar exercise (4) LTI Grammars and Lexicons

3. Bird.gra review General Problems • Incomplete F-structure • Incorrect F-structure • Not enough constraints in the rule • Unification problems LTI Grammars and Lexicons

4. Incomplete F-structures Determiner information is missing from f-structure “A bird flies” and “The bird flies” showed the same F-structure ((subj ((agreement 3sg) (number sg) (root bird))) (form present) (agreement 3sg) (root fly)) LTI Grammars and Lexicons

5. Complete F-structure • Contains all the necessary grammatical information • Be able to reconstruct the original sentence “A bird flies” ((SUBJ ( (NUMBER SG) (AGREEMENT 3SG) (ROOT BIRD) (DET ((NUMBER SG) (DEFINITENESS -) (ROOT A))) )) (FORM PRESENT) (AGREEMENT 3SG) (ROOT FLY)) • Some feature structures are redundant LTI Grammars and Lexicons

6. Incomplete F-structures (2) Grammar problem: (<NP> < == > (<DET> <N>) ( ((x1 number) = (x2 number)) (x0 = x2) )) LTI Grammars and Lexicons

7. Not Enough Constraints The singular noun without determiner can become NP. “Bird flies” may parse. (<NP> < == > (<N>) ((x0 = x1))) Problem: No constraint for number. ((x1 number) =c pl) LTI Grammars and Lexicons

8. Be Aware of Unification (<NP> < == > (<DET> <N>) ((x0 = x1) (x0 = x2))) (<DET> < -- > (t h e) (((x0 definiteness) = +))) (<N> < -- > (b i r d) (((x0 root) = bird) ((x0 number) = sg) ((x0 agreement) = 3sg))) LTI Grammars and Lexicons

9. Be Aware of Unification (cont.) (<NP> < == > (<DET> <N>) ((x0 = x1) (x0 = x2))) (<DET> < -- > (t h e) (((x0 definiteness) = +) ((x0 root) = the))) (<N> < -- > (b i r d) (((x0 root) = bird) ((x0 number) = sg) ((x0 agreement) = 3sg))) LTI Grammars and Lexicons

10. Frequently Seen Problems • Test equations come before Action (x0 = x2) ;action ((x1 agreement) = (x2 agreement)) ;test • No “root” info in f-structure • When submitted: • Write your full name in the grammar • Write more comments in the grammar • Turn off (dmode 2) or trace • Print out the grammar and results files. • lpr –P<printer name> <filename> e.g. lpr –Pshakthi bird.gra LTI Grammars and Lexicons

11. Review: Bird 2 Grammar • Goal: To learn more on unification • Some Problems: • Not scalable semantic features ((x0 semclass) = Morris) • Incomplete f-structures • Incorrect f-structures LTI Grammars and Lexicons

12. Grammar Exercise (3) Test Sentences "A bird flies“ "Birds fly“ "The bird flies“ "The birds fly“ "The cat runs“ "The cats run“ “Morris runs“ “Morris meows“ "Cats meow“ "A cat meows” "The cats meow“ "The penguins run” "A penguin runs" LTI Grammars and Lexicons

13. Grammar Exercise (3)Test Sentences (fail) "A bird fly" "A birds flies" "Birds flies" "Bird flies" "The bird fly" "The birds flies" LTI Grammars and Lexicons

14. Test Sentences (fail) "The cat flies" "The cats fly" "The cat run" "A cat meow" “Morris meow" “Morris flies" "The bird meows" "A penguin meows" “Penguins meow" "The penguin flies" LTI Grammars and Lexicons

15. Semantic Category Bird fly, run, *meow Cat *fly, run, meow Penguin *fly, run, *meow LTI Grammars and Lexicons

16. Semantic Features (noun) Bird (sem-class bird) Cat (sem-class cat) Penguin (sem-class penguin) --------------------------------- (animate +) LTI Grammars and Lexicons

17. Semantic Features (verb) Fly ((subj sem-class) = bird) Meow ((subj sem-class) = cat) Run ((subj animate) = +) LTI Grammars and Lexicons

18. Unification (<N> <--> (c a t s) (((x0 root) = cat) ((x0 number) = pl) ((x0 animate) = +) ((x0 sem-class) = cat) ((x0 agreement) = pl))) (<V> <--> (m e o w) (((x0 root) = meow) ((x0 agreement) = pl) ((x0 subj animate) = +) ((x0 subj sem-class) = cat) ((x0 form) = present))) LTI Grammars and Lexicons

19. Unification (<S> <==> (<NP> <VP>)(((x1 agreement) = (x2 agreement)) ((x0 subj) = x1) (x0 = x2))) LTI Grammars and Lexicons

20. Character-based Parsing Morphological rules can be parsed Input string: tabeta eat-past taberu eat-present (<v-class-1> < -- > (<v-class-1> r u) ((x0 = x1) ((x0 tense) = present))) (<v-class-1> < -- > (<v-class-1> t a) ((x0 = x1) ((x0 tense) = past))) (<v-class-1> < -- > (t a b e) (((x0 root) = taberu)) LTI Grammars and Lexicons

21. Japanese morphology Tabeta eat-past Tabe-sase-ta eat-caus-past Tabe-rare-ta eat-pass-past Tabe-sase-rare-ta eat-caus-pass-past *tabe-rare-sase-ta eat-pass-caus-past *tabe-ta-sase-rare eat-past-caus-pass *tabe-ta-rare-sase eat-past-pass-caus *tabe-rare-ta-sase eat-pass-past-caus *tabe-sase-ta-rare eat-caus-past-pass *tabe-rare-sase eat-pass-caus *tabe-ta-sase eat-past-caus tabe-sase-rare-ta eat-caus-pass-past (<v-class-1> < -- > (t a b e) (((x0 root) = taberu))) (<v-class-1> < -- > (<v-class-1> s a s e) (((x1 pass) = *undefined*) ((x1 tense) = *undefined*) (x0 = x1) ((x0 caus) = +))) (<v-class-1> < -- > (<v-class-1> r a r e) (((x1 tense) = *undefined*) (x0 = x1) ((x0 pass) = +))) (<v-class-1> < -- > (<v-class-1> t a) ((x0 = x1) ((x0 tense) = past))) LTI Grammars and Lexicons

22. Word-based Parsing (<N> < -- > (sushi) (((x0 = root) = sushi))) Instead of: (<N> < -- > (s u s h i) (((x0 = root) = sushi))) For parsing: (parse-list list of symbols $) e.g. (parse-list ‘(a bird flies $)) LTI Grammars and Lexicons

23. Grammar Exercise (4) • Start grammar exercise (4): mlb.gra • Files are in /afs/cs/project/cmt-55/lti/Lab/Modules/ GNL-721/2007/ • Test file: mlb-test.lisp LTI Grammars and Lexicons

24. Next Class: Nov 26 • Return bird2.gra • Return Assignment #1 • Grammar Writing Project Evaluation Criteria • Finish mlb.gra • Start a new exercise LTI Grammars and Lexicons