CS267 Fall 2011Practice Midterm

To study for the midterm I would suggest you: (1) Know how to do (by heart) all the practice problems. (2) Go over your notes at least three times. Second and third time try to see how much you can remember from the first time. (3) Go over the homework problems. (4) Try to create your own problems similar to the ones I have given and solve them. (5) Skim the relevant sections from the book. (6) If you want to study in groups, at this point you are ready to quiz each other. The practice midterm is below. Here are some facts about the actual midterm: (a) It is closed book, closed notes. Nothing will be permitted on your desk except your pen (pencil) and test. (b) You should bring photo ID. (c) There will be more than one version of the test. Each version will be of comparable difficulty. (d) One problem (less typos) on the actual test will be from the practice test.

1. What is the probability ranking principle?
2. Consider all the words in this problem as our corpus. Draw the term frequency table for this corpus.
3. Give the maximum likelihood estimate of the phrase: "the words in the table" using the corpus of problem 2.
4. Briefly explain how a first-order language model could be smoothed with a 0th order model.
5. Explain roughly what each of the following pieces of software does: Nutch, Lucene, Solr.
6. Give the algorithm for implementing the inverted-index next method using Galloping search.
7. View each problem in this practice test as our corpus. Calculate the IDF score for the word "corpus".
8. Define what a cover is. Explain the scoring function used for Proximity Ranking.
9. Give the formula for mean average precision and explain with an example how it is calculated.
10. What are character n-grams?