1 / 6

WAES3303: NLP

WAES3303: NLP. rmana@um.edu.my. GRAMMAR. In constructing a grammar for a language , we are interested in: Generality : the range of sentences the grammar analyzes correctly Selectivity : the range of non-sentences it identifies as problematic

gwenb
Download Presentation

WAES3303: NLP

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. WAES3303: NLP rmana@um.edu.my

  2. GRAMMAR • In constructing a grammar for a language, we are interested in: • Generality: the range of sentences the grammar analyzes correctly • Selectivity: the range of non-sentences it identifies as problematic • Understandability: The simplicity of the grammar itself * Retain its simplicity & generality as it is extended

  3. Characteristics • Pay attention to the way sentence is divided into its subparts (constituent). • Make the solutions generalizable as you can. • Test (when constructing a group of words forms a particular constituent): • If the proposed constituent does not conjoin in some sentence with constituent of the same class, it is probably incorrect • Inserting the proposed constituent into another sentences that take the same category of constituent

  4. Generative Capacity • Grammatical formalisms based on rewrite rules can be compared according to their generative capacity(GC). • GC is the range of languages that each formalism can describe. • Formal language allow a precise mathematical characterization (vs. Natural Language)

  5. GC cont. • Regular Grammar: a grammar in which the RHS of every rule consists one terminal symbol possibly followed by one nonterminal. • CFG • CSG • Type 0 • Hierarchy of Languages: Chomsky Hierarchy (1956)

  6. Parsing • Parsing as Search Procedure • Top-Down • Bottom-Up • A Bottom-Up Chart Parser • Transition Network • Recursive Transition Network (RTN) • Top-Down Chart Parsing • Augmented Transition Network (Parsing with Feature)

More Related