The reliability of a hard-disk drive is typically described in terms of the mean time between failures (mtbf). this is measure in drive-hours per failure (how many hours the drive is operating divided by the number of failures). if a disk farm contains 1000 drives each of which has a 750,000-hour mtbf, on average a drive will fail once per :

Show that there is a language a ⚆ {0, 1} â— with the following properties: 1. for all x â a, |x| ≤ 5. 2. no dfa with fewer than 9 states recognizes a. hint: you don’t have to define a explicitly; just show that it has to exist. count the number of languages satisfying (1) and the number of dfas satisfying (2), and argue that there aren’t enough dfas to recognize all those languages. to count the number of languages satisfying (1), think about writing down all the strings of length at most 5, and then to define such a language, you have to make a binary decision for each string about whether to include it in the language or not. how many ways are there to make these choices? to count the number of dfas satisfying (2), consider that a dfa behaves identically even if you rename all the states, so you can assume without loss of generality that any dfa with k states has the state set {q1, q2, . . , qk}. now think about how to count how many ways there are to choose the other four parts of the dfa.

Drag each label to the correct location on the imagelist the do’s and don’ts of safeguarding your password. keep yourself loggedin when you leave your computer. don’t write your password down and leave it whereothers can find it. share your password with your friends. each time you visit a website, retain the cookies on your computer. use a long password with mixed characters.

Q13 what function does a security certificate perform? a. creates user accounts b. scrambles data c. identifies users d. creates password policies e. provides file access