Overview
This lecture covers structural ambiguity in sentences, focusing on how different structures lead to different interpretations. It explains tests for identifying constituents and methods to disambiguate sentences.
Structural Ambiguity
- Structural ambiguity occurs when a sentence can be parsed in multiple ways, leading to different meanings.
- Example: "Darth Vader will poke the dog with the lightsaber" has two interpretations depending on what "with the lightsaber" modifies.
Constituent Tests
- The do-so substitution test checks if a group of words forms a verb phrase (e.g., "Darth Vader will do so with the lightsaber").
- The one-substitution test checks if a group of words forms a noun phrase (e.g., "Darth Vader will poke this one").
- Pronoun substitution can reveal misgrouped constituents when interpretation changes.
Sentence Structure Analysis
- In ambiguous sentences, identify what the prepositional phrase (PP) modifies (noun or verb).
- Attach auxiliary verbs (like "will") to the largest verb phrase.
- Use substitution to confirm correct constituent structure.
- Avoid grouping determiners and nouns as a constituent when a PP modifies only the noun.
Disambiguating Sentences
- Move the PP to the front (e.g., "In Buffalo, dozens rally for peace") to make intended meaning clear.
- Rephrase sentences to separate ambiguous attachments.
- Use paraphrasing to clarify which constituent the modifier is attached to.
Examples Reviewed
- "Dozens rally for peace in Buffalo" (ambiguous: rally location vs. peace type).
- "Spider-man memorized the digits of pi on that wall" (ambiguous: digits' location vs. where memorization happened).
Key Terms & Definitions
- Structural ambiguity — When a sentence can be interpreted in more than one way due to its structure.
- Constituent — A group of words functioning together as a unit within a sentence.
- Prepositional phrase (PP) — A phrase beginning with a preposition, modifying a noun or verb.
- Do-so substitution — A test for identifying verb phrase constituents by replacing them with "do so".
- One-substitution — Replacing a noun phrase with "one" to check its constituency.
- Auxiliary verb — A helper verb (e.g., "will") that provides tense, aspect, or mood.
Action Items / Next Steps
- Practice drawing syntax trees for ambiguous sentences using constituent tests.
- Complete provided practice exercises to prepare for the upcoming term test.
- Ask questions on Discord or in discussion forums if substitution/acceptability is unclear.
- Review all constituent tests and structural ambiguity examples before the term test.