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Chapter 22: Communication

Chapter 22: Communication. April 6, 2004. 22.1 Communication As Action. Signs vs. Language Speaker issues an Utterance (consisting of Words) to a Hearer Types: query, inform, request, acknowledge, promise. Formal Language Components. Non-terminal Symbols, e.g. computer

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Chapter 22: Communication

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  1. Chapter 22: Communication April 6, 2004

  2. 22.1 Communication As Action • Signs vs. Language • Speaker issues an Utterance (consisting of Words) to a Hearer • Types: query, inform, request, acknowledge, promise

  3. Formal Language Components • Non-terminal Symbols, e.g. computer • Terminal Symbols, e.g. S • Rewrite Rules, e.g. S  NP VP • Grammars are usually based on a phrase structure • Semantics • Pragmatics

  4. Chomsky Hierarcy • Recursively Enumerable: no restrictions • Context Sensitive: |rhs| >= |lhs| • Context Free: left hand side is a non-terminal • Regular: NT  T | T NT

  5. Communication Components • Intention • Generation • Synthesis, e.g. talking, e-mail, etc. • Perception, e.g. OCR, speech recognition, etc. • Analysis: analysis, semantic interpretation, pragmatic interpretation (Figure 22.1) • Disambiguation • Incorporation (Figure 22.2)

  6. 22.2 A Formal Grammar for a Fragment of English • Figure 22.3: lexicon, open classes vs. closed classes • Figure 22.4: the non-terminal symbols in the grammar are S, NP, VP, PP, RelClause • Є0 both overgenerates and undergenerates

  7. 22.3 Syntactic Analysis (Parsing) • Top-Down. Problem: left recursive rules. • Bottom-Up. Figure 22.5. • Chart Parsing. Figures 22.6, 22.8, 22.9. Notion of a complete edge. Uses dynamic programming.

  8. 22.4 Augmented Grammars • Figure 22.11. Distinguishes subject from object. • Definite Clause Grammar (DCG). Allows parameters for non-terminals. • Figures 22.12 and 22.13. Verb sub-categorization. Verb([NP, PP])  give | hand | …

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