06.03.2017 Views

Mathematics for Computer Science

e9ck2Ar

e9ck2Ar

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

“mcs” — 2017/3/3 — 11:21 — page 923 — #931<br />

21.2. Random Walks on Graphs 923<br />

Problems <strong>for</strong> Section 21.2<br />

Practice Problems<br />

Problem 21.5.<br />

Consider the following random-walk graphs:<br />

1<br />

x<br />

y<br />

1<br />

Figure 21.4<br />

w<br />

1<br />

0.9<br />

z<br />

0.1<br />

Figure 21.5<br />

1/2<br />

1/2<br />

1 a b c<br />

1/2<br />

d<br />

1<br />

1/2<br />

Figure 21.6<br />

(a) Find d.x/ <strong>for</strong> a stationary distribution <strong>for</strong> graph 21.4.<br />

(b) Find d.y/ <strong>for</strong> a stationary distribution <strong>for</strong> graph 21.4.<br />

(c) If you start at node x in graph 21.4 and take a (long) random walk, does the<br />

distribution over nodes ever get close to the stationary distribution?<br />

(d) Find d.w/ <strong>for</strong> a stationary distribution <strong>for</strong> graph 21.5.

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!