Post on 10-May-2015
transcript
Syntax & Stylistics
Revealing the Bones of Language
Intuitions about Words Belonging Together
My cat eats ate really fancy restaurants
[[my cat ][ eats [ at [[ really fancy ] restaurants ]]]]
• There seems to be a closer relationship between “really” and “fancy” than btw. “eats” and “at.”
• Syntax is the way capture these intuitions.
Constituent Structure
• Sentences are not just a linear string of words. We can use a tree structure to represent these relationships:
My cat eats at really fancy restaurants
Using Introspective Data
Syntax is fun!
Intuitions about Language
• You’re going to be making judgments about sentences you’ve never seen before.
• What criteria are we using?– Is the sentence well-formed?– Does it conform to your dialect?
• We’re not talking about meaning.– Syntax is different from Semantics
Form vs. Meaning
• Some famous sentences:a) Colorless green ideas sleep furiously. (?)b) Revolutionary new ideas occur infrequently. (√)
c) ?I’m going to visit that country last year. (?)d) I’m going to visit that country next year. (√)
• Meaning may broken, but syntax is still good.
Introspective Judgments
• We’re using acceptability and ambiguity as a window on our own grammar.
• The grammar we create may generate sentences we wouldn’t find acceptable.– Infinitely long– Center embedded– Silly meanings
Constituents
• Further approximation:– Rather than being linear strings of words,
sentences contain constituents.– Constituents are groups of words that function as
a unit with respect to grammatical processes.– Constituents can be grouped into larger
constituents.– The hierarchical organization of sentences
represents the structure of constituents.
Constituent Tests
• It was X that Y.– The greedy mouse devoured the cheese in the
cupboard.• It was the greedy mouse that devoured the cheese in
the cupboard.• It was the cheese in the cupboardthat the greedy
mouse devoured.
Constituent Tests
• Answer to a Question:– What did the greedy mouse do?• “devoured the cheese in the cupboard.”
– Where did the greedy mouse devour the cheese?• “in the cupboard.”
Constituent Tests
• Replacement with a proform (pronoun, proverb, proadjective, propreposition).– Kozo loves eating at really fancy restaurants, and
Dori loves to too. (proverb)– The compulsive mouse ate the cheese but he did
not eat the tuna. (pronoun)– Kozo is quite thoroughly independent minded, but
Dori is less so. (proadjective)
Constituent Test
• Deletion– My dog likes to eat at really fancy restaurants.– My dog likes to eat at restaurants.
What’s a Constituent?
• Are the underlined strings of words constituents or not?a) Humpty Dumpty washed himself with soapy water.b) The greedy mouse devoured the cheese in the tower.c) The Cheshire Cat dislikes grey mice with pink tails.d) The Mad Hatter will give some herbal tea to Alice.e) Humpty Dumpty and the Cheshire Cat never eat together
Constituent Tests
• It was X that Y• Replacement with a proform• Answer to a question• Deletion
Ambiguity
• Some sentences have multiple meanings:– “Wanted: Man to take care of cow that does not
smoke or drink.”
• Ambiguity provides evidence about the structure.– Frege: The meaning of a sentence is composed of
the meanings of the parts and their mode of combination.
A Richer Hierarchical Structure
The dog that is chasing the ball is limping
Ambiguity
• “The harbor pilot saw the ship’s captain with the telescope.”One sentence, two meanings.
Meaning 1: The harbor pilot had the telescope.Meaning 2: The ship’s captain had the telescope.
• The only way for the same string of unambiguous words to have two meanings is for the structures (mode of combination) to be different.
Ambiguity
The harbor pilot saw the ship’s captain with a telescope
The harbor pilot saw the ship’s captain with a telescope
Each meaning is associated with a different structure:
Find the Ambiguity
• Describe the two meanings in each of the following ambiguous sentences:– Wanted: Man to take care of cow that does not
drink or smoke.– The old cat and dog sat on the porch.– Tibetan history teacher to visit the college.– More intelligent administrators are required to
solve this problem.
Ambiguity
• Make up four more sentences that are ambiguous in the same way as “The pilot saw the captain with a telescope.” Use words such as to, from under, without and on.
Concatenation
• First approximation: Constituent structure as simple concatenation.– As in mathematics: addition.– Phrase structure corresponds to the order of
words from the beginning to the end:a)Kozo ate Dori’s dinner.b)Kozo + ate + Dori’s + dinner
Concatenation as Addition
• Addition is commutative:2 + 4 = 4 + 2
– Order doesn’t matter.
• Language is not commutative:Boy loves girl ≠ Girl loves boy.
(Hence, the entire history of Western literature.)
Dori ate Kozo’s dinner ≠ Kozo ate Dori’s dinner
Structured Concatenation
• What if we combine the first two elements to create a new object, then combine the new object with the next word to the right…– Kozo & ate– (Kozo & ate) & Dori’s– ((Kozo & ate) & Dori’s) & dinner
• Solves part of the problem:– (Kozo & ate) ≠ (Dori & ate)
Problems
• Structured concatenation doesn’t capture the intuitions we have about language.
• “Dori’s” is structurally closer to “ate” than to “dinner.”
• (1(2(3 Kozo & ate )3 & Dori’s )2 & dinner)1
• “Dori’s” belongs to the set enclosed by (2 …)2, excluding “dinner.”
• Our intuitions tell us that this isn’t right.
Reverse Order?
• What if we collect things into constituents from R to L?– Dori’s & dinner– ate & (Dori’s & dinner)– Kozo & (ate & (Dori’s & dinner))
• Resulting in this structure:(1Kozo & (2 ate & (3Dori’s & dinner)3)2)1
Reverse Order
Kozo ate Dori’s dinner
Problems
(1the & (2 cat & (3 ate & (4Dori’s & dinner)4)3)2)1
The cat ate Dori’s dinner
• Still doesn’t capture our intuitions about the relatedness of phrases, e.g., “the cat”
Regular (Markov) Grammars
Also called “Finite State Automata.” Each dot represents a state, the words are functions from state to state.
man
men
comes
came
The old● ●
●
●
●●
very
Regular (Markov) Grammar
dog
dogs
snores
snore
The old● ●
●
●
●●
very
What sentences can you generate with this grammar?
Grammaticality?
• Are the following sentences grammatical according to this grammar?– The old dog snores.– The very old dog snores.– The very old dogs snore.– The really old dogs snore.– The very old cats snore.– The very, very, very, old dogs sleep.
Problems
• Regular grammars have no “memory.”– They only know what happened on the last node.
• We know that human languages do have a memory.– Missile– Anti missile missile– Anti anti missile missile missile– Etc.
Mirror Languages
• In this language, we have a pattern where the number of times the word “missile” occurs is exactly one more than the number of times the word “anti” occurs (anbn+1).
• Regular grammars can’t do this, b/c they can’t count the number of times a particular node was passed.
No Memory
anti missile
●●
• There is a dialect of Swiss German that has this property.• Consider also:
“Jon, Stephen, and Bill like cats, dogs, and fish, respectively.”
Question Formation
• Subject-Aux Inversiona) Kozo has eaten.b) Has Kozo eaten?
• First hypothesis: invert the first two words in the sentence.a) The cat has eaten.b) *Cat the has eaten?* = unacceptable
Question Formation
• Second hypothesis: move the first auxiliary verb to the beginning of the sentence:– Kozo the wonder dog has eaten.– Has Kozo the wonder dog eaten?
• Problem: what about two aux verbs?– The dog that was chasing the ball is limping.– *Was the dog chasing the ball is limping?
Grammatical, but not Acceptable
• Consider the following sentences:– Colorless green ideas sleep furiously (rejected for
semantic reasons).– The mouse the cat the dog chased ate died
The mouse the cat the dog chased ate died
We might reject this sentence because it is just to complex to understand, even though it conforms to the rules of the grammar.