1 / 25

CPE 480 Natural Language Processing

This lecture by Asst. Prof. Nuttanart Facundes, Ph.D., delves into the complexities of semantics in natural language processing. It explores how the meaning of words varies with context, the challenges of representing meaning, and the formalisms used, including First-Order Predicate Calculus, semantic networks, and frame-based representations. The lecture also discusses the principle of compositionality, the structure of language in conveying meaning, and the use of semantic attachments to augment context-free grammars. Learn about the different sentence types and their roles in communication.

starr
Télécharger la présentation

CPE 480 Natural Language 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. CPE 480 Natural Language Processing Lecture 6: Semantics--From words to sentences to idioms Asst. Prof. Nuttanart Facundes, Ph.D.

  2. Theories of Meaning • Words have different meaning, depending on the context in which they are used • What is the meaning of a word? • How can we represent the meaning? • What formalisms can be used?

  3. 4 Representation Approaches • First-Order Predicate Calculus • Semantic Networks • Conceptual Dependencies • Frame-Based Representations

  4. Correspondences between representations • They all share a common foundation:  meaning representation consists of structures composed of sets of symbols Symbol Structures  are objects and relations among objects

  5. Meaning structure of language • Various ways by which human language conveys meaning • Form-meaning associations • Word-order regularities • Sense systems • Conjunctions and quantifiers • Predicate-argument structure

  6. Problems with FOPC • Hard to represent beliefs • For example: I believe that Mary ate British food.

  7. Principle of Compositionality (Frege) • The meaning of a sentence is composed by the meaning of its parts

  8. Semantic Augmentations to Context-Free Grammars • Augmenting context-free grammar rules with semantic attachments • Attachments = Instructions that specify how to compute the meaning representation of a construction from the meanings of its consistent parts

  9. Solution: Lambda Calculus

  10. Different Sentences • Declarative: Flight 487 serves lunch. • Imperative: Serve lunch. • Yes/No Questions: Does Flight 207 serve lunch? • Wh-Questions: Which flights serve lunch?

  11. The Role of Sentences • Declarative  intended to convey factual information • Imperative  request for an action • Yes/No Questions  request for affirmative/negative answer • Wh-Questions  request for information

More Related