Parsing

Question 1

Ambiguity with prepositional phrases

Answer 1

For n prepositional phrases, there are 2^n possible parse trees.

Question 2

Top-down or Bottom-up strategy

Answer 2

Brute force

Inefficient (2^n)

Question 3

Chart parsers

Answer 3

Numbers the spaces between words, then computes the variables (phrase-type symbols) that can cover each span

Avoids reconstructing partial parses over and over again

Question 4

CKY Parser

Answer 4

A type of chart parser

Order N^3

Needs a grammar in Chomsky Normal Form

Question 5

Assigning probabilities to a parse tree

Answer 5

Label each node with the probability of the label.

The probability of the tree is the product of the probabilities of the labels.