CS 484 - Artificial Intelligence
Fall 2005
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Homework 9
1) Suppose one is intereted in a rare syntactic construction, perhaps parasitic gaps, which occurs on average once in 100,000 sentences. Joe Linguist has developed a complicated patter matcher that attemps to identify sentences with parasitic gaps. It's pretty good, but it's not perfect: if a sentence has a parasitic gap, it will say so with probability 0.95, if it doesn't, it will wrongly say it does with probability 0.005. Suppose the test says that a sentence contains a parasitic gap. What is the probability that this is true?
2) Compute the probability of the event 'A period occurs after a three-letter word and this period indicates an abbreviation (not an end-of-sentence marker),' assuming the following probabilities.
- P(is-abbreviation|three-letter-word) = 0.8
- P(three-letter-word) = 0.0003
3) Create a naive bayes classifier from the movie data on page 279. Using the m-estimator, classify the new data on page 288. Which of these classfications agree with the decision tree on page 277 about whether the films will be a success at the box-office?