CS267 Fall 2018Practice Midterm 2

Studying for one of my tests does involve some memorization. I believe this is an important skill. Often people waste a lot of time and fail to remember the things they are trying to memorize. Please use a technique that has been shown to work such as the method of loci. Other memorization techniques can be found off the Wiki Page for Moonwalking with Einstein. Given this, to study for the midterm I would suggest you:

• Know how to do (by heart) all the practice problems.
• Go over your notes at least three times. Second and third time try to see how much you can remember from the first time.
• Go over the homework problems.
• Try to create your own problems similar to the ones I have given and solve them.
• Skim the relevant sections from the book.
• 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. How would the codepoint Ԉ, U+0508, be encoded in UTF-8?
2. Briefly explain the following concepts: (a) per-term index and (b) dictionary interleaving
3. Explain and give a small example of how sort based index construction works.
4. Write down the BM25 formula. Give an example of using it for a query with at least two terms.
5. Write the following query using the region algebra: Lines spoken by Caesar in the play Julius Caesar.
6. What files does the trec_eval need in order to compute statistics? Briefly describe their format.
7. Explain how each `gamma` and Golomb code work to encode gaps. Give an example of how these codes could be used to encode the number 5. State any assumptions you use.
8. Briefly explain how vByte and Simple-9 work.
9. Briefly explain how logarithmic merging index construction works.
10. Give the formulas for LMJM and LMD and explain each of their components.