Semantics, part 2

1. Semantics, part 2 December 3, 2012

2. And Then There Were Three • Course Evaluations at the end of today’s lecture! • Semantics/Pragmatics homework still due on Wednesday • I will also pass out a final exam review checklist on Wednesday • Wednesday: some comments on language preservation • Friday: an opportunity to ask some review questions • Semantics homeworks will be graded by Friday

3. Meaning Review • Referent: the actual thing in the world an expression picks out. • Extension: a set of referents (= a predicate) in some possible world. • Sense: what an expression refers to in all possible worlds. • Truth: a proposition is true if the referent of its subject is contained in the extension of its predicate. • Meaning: • The meaning of a proposition is the set of conditions in which that proposition is true. • Truth conditions

4. Compositionality • By the way: • The idea that the meaning of a sentence can be calculated from the meaning(s) of its parts is the principle of compositionality. • Consider this sentence: • The President of the United States is a white male. • Is this true? How do you know? • How about this sentence: • Santa Claus is a white male.

5. Types of Sentences • Propositions may be distinguished on the basis of the kinds of worlds in which they may be true. • Synthetic propositions may be true or false, depending on the state of affairs in the world. • Analytic propositions are always true, no matter what the state of the world. • Contradictions are always false, no matter what the state of the world. • Quick Write check.

7. Moving On (Again) • There are several different ways to study meaning in language: • Pragmatics • The meaningful use of linguistic expressions in conversation and discourse. • Compositional Semantics How the meaning of phrases and sentences is built up from the meanings of individual words. • Lexical Semantics The meaning of individual words, and how they’re related to one another.

8. Lexical Semantics • Here are two basic meaning relationships that words can have with one another: • Synonymy • Two words have the same meaning • couch/sofa, groundhog/woodchuck, hide/conceal • = real-world extensions are identical • Hyponymy • one word’s extension is a subset of another word’s extension • poodle/dog, laptop/computer, gas giants/planets

9. Synonym Schematic Fido Marmaduke Garfield Rex Spot Snoopy Fifi Mr. Meowser Lassie Scooby The Death Star canines and dogs are synonyms is a dog is a canine

10. Hyponym Schematic Fido Marmaduke Garfield Rex Spot Snoopy Fifi Mr. Meowser Lassie Tinkerbell The Death Star poodle is a hyponym (subset) of dog is a dog is a poodle

11. Another One • Antonymy: when words that mean the “opposite” of each other • Complementary antonyms: • Everything in the world is one or the other • unmarried/married, present/absent, visible/invisible • Relational antonyms: • Reflect a symmetrical connection between each other • give/receive, buy/sell, teacher/pupil • employer/employee, adviser/advisee • Scalar antonyms: words form two ends of a scale • hot/cold, happy/sad, big/small, fast/slow

12. Homonyms/Homophones • Homonyms/Homophones are words with: • same pronunciation • unrelated meanings • from Greek: /homo-/ “same” + /onyma/ “name” • Examples: • trunk (of an elephant), trunk (chest), trunk (of a tree) • also: bear, bare • Homonyms can create ambiguity: • We saw her duck.

13. Polysemy • Polysemy is when one word has several different, but related meanings. • From Greek: /poly-/ “many” + /sema/ “signal” • Examples: • Mouth of a river ~ mouth of an animal • A baseball diamond ~ a geometric diamond ~ a diamond stone

14. Intersection • Compositional semantics, continued... • We have discussed how the referents of nouns and the extensions of predicates get put together to form a meaningful proposition. • Now let’s consider adjectives and nouns in noun phrases. • Simplest case: pure intersection • black dogs = • the set of all dogs • intersected with • the set of all black things

15. Pure Intersection Schematic Marmaduke Odie Charcoal Lassie Spot Rex Darth Vader Spuds Oil dogs black dogs black things

16. Pure Intersection of Geekery

17. Semantic Features • Idea: the meaning of a word can be precisely determined by the pure intersection of predicates of which it is a hyponym (subset). • Example: “square” • [TWO-DIMENSIONAL, FOUR-SIDED, EQUAL-SIDED] • Example: “bachelor” • [HUMAN, MALE, UNMARRIED] • The predicate sets form a word’s semantic features • “hen” and “mare” share the feature [FEMALE] • “bachelor” and “woman” share the feature [HUMAN]

18. Verb Features • The same semantic feature can be expressed by a variety of different verbs. • Example: the feature [GO] • reflects a change in position • fly, walk, roll, stumble, run, crawl, etc. • More subtle examples of [GO]: • give: “John gave Mary an engagement ring.” • John Mary • ring • “The boy threw the ball over the fence.”

19. A Syntax Flashback • Remember that, in syntax, we learned that different verbs require specific complement structures. • For instance, transitive verbs require an object NP in their verb phrases. • I devoured the sandwich. • I met the Professor. • Similarly, ditransitive verbs can take two objects in their verb phrases. • The dog trainer sold me a chew toy. • Larry gave Shelly the textbook.

20. Syntax/Semantics • There are sub-features of [GO], which are reflected in constraints on verb complements in English. • [BALLISTIC]: a one-time [GO] V’  V NP NP • [SUSTAINED]: a continuous [GO] *V’  V NP NP • Ballistic VerbsSustained Verbs • throw the boy a ball *push the boy a ball • toss the boy a ball *pull the boy a ball • kick the boy a ball *lift the boy a ball • fling the boy a ball *drag the boy a ball

21. Role-playing • The objects of ditransitive verbs can be expressed in two different syntactic ways: • Larry gave Shelly the textbook. (NP NP) • Larry gave the textbook to Shelly. (NP PP) • Despite the syntactic differences, each noun plays the same role in both sentences: • Larry: Agent (the entity performing the action) • Textbook: Theme (thing being acted upon) • Shelly: Recipient (being coming into possession of something)

22. Thematic Roles • Verbs have semantic requirements. • For a sentence to make sense, it has to include nouns which can play the roles required by the verb. • give: Agent; Theme; Recipient • Larry gave Shelly the textbook. • Larry gave the textbook to Shelly. • Shelly was given the textbook by Larry. • !Anger gave Shelly the textbook.

23. Other Thematic Roles • Experiencer • = animate being that has a perceptual or mental experience. • Ex: Susan heard the music. • Source • = the origin of a change. • Ex: Jan arrived from Detroit. • Instrument • = the means used to accomplish an action (not agent) • Ex: The hammer cracked the window.

24. Other Thematic Roles • Goal • = the end point of a change in location or possession. • Ex: Chris hitchhiked to Alaska. • Location • = the place where an action occurs. • Ex: Neil Young played a show in Winnipeg.