link analysis

Homework

1. Chapter 14. Exercise 1 - Show the values that you get if you run two rounds of computing hub and authority values on the network of Web pages in Figure 14.15 (i.e., the values computed by the k-step hub–authority computation when we choose the number of steps k to be 2).

Show the values both before and after the final normalization step, in which we divide each authority score by the sum of all authority scores and divide each hub score by the sum of all hub scores. (It’s fine to write the normalized scores as fractions rather than decimals.)

2. Chapter 14. Exercise 2 –

a. Show the values that you get if you run two rounds of computing hub and authority values on the network of Web pages in Figure 14.16. (That is, the values computed by the k-step hub-authority computation when we choose the number of steps k to be 2.)

Show the values both before and after the final normalization step, in which we divide each authority score by the sum of all authority scores, and divide each hub score by the sum of all hub scores. (We will call the scores obtained after this dividing-down step the normalized scores. It’s fine to write the normalized scores as fractions rather than decimals.)

b. Due to the symmetry of nodes A and B in part (a), you should have seen that they get the same authority scores. Now let’s look at what happens to the scores when node E, which links to B, decides to link to C as well. This produces the new network of Web pages shown in Figure 14.17.

Similarly to part (a), show the normalized hub and authority values that each nodegets when you run the 2-step hub-authority computation on the new network in Fig-ure 14.17.

c. In (b), which of nodes A or B now has the higher authority score? Give a brief explanation in which you provide some intuition for why the difference in authority scores between A and B in (b) turned out the way it did.

3. Chp 14 – Ex 3 (a) and (b) – Skipping (c) - In Chapter 14, we discussed the fact that designers of Web content often reason ex-plicitly about how to create pages that will score highly on search engine rankings. Ina scaled-down setting, this question explores some reasoning in that style.

a. Show the values that you get if you run two rounds of computing hub and authority values on the network of Web pages in Figure 14.18. (That is, the values computed by the k-step hub-authority computation when we choose the number of steps k to be 2.)

Show the values both before and after the final normalization step, in which we divide ach authority score by the sum of all authority scores, and divide each hub score by the sum of all hub scores. (We will call the scores obtained after this dividing-down step the normalized scores. It’s fine to write the normalized scores as fractions rather than decimals.)

b. Now we come to the issue of creating pages so as to achieve large authority scores, given an existing hyperlink structure.

In particular, suppose you wanted to create a new Web page X, and add it to the network in Figure 14.18, so that it could achieve a (normalized) authority score that is as large as possible. One thing you might try is to create a second page Y as well, so that Y links to X and thus confers authority on it. In doing this, it’s natural to wonder whether it helps or hurts X’s authority to have Y link to other nodes as well.

Specifically, suppose you add X and Y to the network in Figure 14.18. In order to add X and Y to this network, one needs to specify what links they will have. Here are two options; in the first option, Y links only to X, while in the second option, Y links toother strong authorities in addition to X.

i. Option 1: Add new nodes X and Y to Figure 14.18; create a single link from Y to X; create no links out of X.

ii. Option 2: Add new nodes X and Y to Figure 14.18; create links from Y to each of A,B, and X; create no links out of X

For each of these two options, we’d like to know how X fares in terms of its authority score. So, for each option, show the normalized authority values that each of A, B, and X get when you run the 2-step hub-authority computation on the resulting network (as in part (a)). (That is, you should perform the normalization step where you divide each authority value down by the total.) For which of Options 1 or 2 does page X get a higher authority score (taking normalization into account)? Give a brief explanation in which you provide some intuition for why this option gives X a higher score.

SEO Question

4. For the SEO question, what are the factors you should consider when improving SEO for your webpage? Please give a short but concise 3-4 sentence answer of factors that you should look for when trying to improve your SEO