1 / 28

Algorithm Schemata and Data Structures in Syntactic Processing

Algorithm Schemata and Data Structures in Syntactic Processing. By Martin Kay. 발표자 : 임성신 E-mail : sslim@pusan.ac.kr. Contents. Parsing Top-down parsing Buttom-up parsing Chart parsing CKY Bottom-up Chart Parsing Top-down Chart Parsing. What is parsing?.

hayes
Télécharger la présentation

Algorithm Schemata and Data Structures in Syntactic Processing

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Algorithm Schemata and Data Structures in Syntactic Processing By Martin Kay 발표자 : 임성신 E-mail : sslim@pusan.ac.kr

  2. Contents • Parsing • Top-down parsing • Buttom-up parsing • Chart parsing • CKY • Bottom-up Chart Parsing • Top-down Chart Parsing

  3. What is parsing? • parsing involves recognising an input string and assigning a structure to it • parsing involves: • a grammar e.g. a context-free grammar • an input string • a parsing algorithm: a set of instructions for applying the grammar to the input stringe.g. whether to use top-down or bottom-up methods

  4. Applications of Parsing • grammar checking in word processing systems • as a basis for semantic analysis • to support applications of NLP such as • machine translation • question answering • information extraction

  5. Top-down production 예문 : radio broadcasts pay

  6. Start Top-down Parsing S NP VP D N V NP D N the dog saw the cat

  7. Buttom-up Production

  8. Bottom-up parsing S NP VP D N V NP D N the dog chased the cat Start

  9. Parsed Sentence S NP VP VP PP Verb NP Prep NP Det Noun Det Noun Det Noun the boy hits the dog with a rod

  10. NP VP Verb VP NP PP Verb Det NP Noun Prep NP Det Noun Det Noun Det Noun Top-down Parsing S Failed the boy hits the dog with a rod

  11. S S Prep NP NP Verb VP NP PP S Verb NP Prep NP Det Noun Det Noun Det Noun Bottom-up Parsing Failed the with hits boy the a dog rod NP S Det VP Prep Noun PP Verb NP Det Det NP Noun Noun the boy hits the dog with a rod

  12. NP S NP NP NP VP VP Prep VP NP VP VP PP Verb NP Prep NP Det Noun Det Noun Det Noun the boy hits the dog Bottom-up Parsing with a rod S VP Prep PP Det NP Noun with a rod

  13. Chart Parsing • chart parsing is a form of dynamic programming • dynamic programming solves problems by filling in tables with solutions to sub-problems • when complete, the tables contain all the solutions to the sub-problems needed to solve the problem • in chart parsing, this involves storing subtrees for constituents that are found • once found and stored, subtrees can be looked up - this avoids reparsing

  14. the boy hits the dog with a rod CKY(Cocke-Kasami-Younger) S VP S VP PP NP NP NP Det Noun Verb Det Noun Prep Det Noun

  15. 예문 : Failing students looked hard. • S → NP VP • NP → A N • NP → PRP N • VP → V A • VP → V AV • A → failing, hard, … • PRP → failing, … • N → students, … • V → looked, … • AV → hard, …

  16. S NP NP S AV PRP A N V N N A Bottom-up Chart Parsing(1/4) VP N VP N Failing student looked hard

  17. VP VP AV AV A V V V A Bottom-up Chart Parsing(2/4) AV A Failing student looked hard

  18. S S VP VP VP VP NP NP N N AV AV PRP PRP A V A V N N Bottom-up Chart Parsing(3/4) Failing student looked hard

  19. VP VP NP NP AV S S AV A VP VP A N A V N V A N N Bottom-up Chart Parsing(4/4) Failing student looked hard

  20. Parsing Graph & Table

  21. ? S AV PRP A N V A Top-down Chart Parsing Initial Step Failing student looked hard

  22. ? S ? ? ? ? ? NP VP N N A ? NP NP S PRP Top-down Chart Parsing(1/6) Failing student looked hard

  23. ? VP ? Failing ? Failing ? ? student Failing student ? A A NP VP N A N N N A S N A NP NP NP NP S Top-down Chart Parsing(2/6) Failing student looked hard

  24. ? ? ? VP Failing student NP VP S N PRP Failing Failing ? student ? ? NP NP NP PRP PRP PRP N N N N NP S PRP Top-down Chart Parsing(3/6) Failing student looked hard

  25. looked ? looked ? ? hard VP VP VP V V V A A A A V Top-down Chart Parsing(4/6) Failing student looked hard

  26. looked ? looked ? ? hard VP VP VP V V V AV AV AV V AV Top-down Chart Parsing(5/6) Failing student looked hard

  27. ? looked hard VP VP student looked Failing Failing student hard V A V A A A N N S S VP NP NP Top-down Chart Parsing(6/6) Failing student looked hard

  28. Parsing Graph & Table

More Related