Explain what PKI is. Note: don't just state that PKI is cryptography. Explain how the public and private key pair works. How does PKI can be used in an online contract to support Authenticity and Nonrepudiation. Explain how the public and private key makes authenticity verifiable and enables nonrepudiation.

Some of your friends have gotten into the burgeoning field of time-series data mining, in which one looks for patterns in sequences of events that occur over time. purchases at stock exchanges"what's being bought" are one source of data with a natural ordering in time. given a long sequence s of such events, your friends want an efficient way to detect certain "patterns" in them"for example, they may want to know if the four events buy yahoo, buy ebay, buy yahoo, buy oracle occur in this sequence s, in order but not necessarily consecutively. they begin with a collection of possible events (e. g., the possible transactions) and a sequence s of n of these events. a given event may occur multiple times in s (e. g., yahoo stock may be bought many times in a single sequence s). we will say that a sequence s is a subsequence of s if there is a way to delete certain of the events from s so that the remaining events, in order, are equal to the sequence s . so, for example, the sequence of four events above is a subsequence of the sequence buy amazon, buy yahoo, buy ebay, buy yahoo, buy yahoo, buy oracle their goal is to be able to dream up short sequences and quickly detect whether they are subsequences of s. so this is the problem they pose to you: give an algorithm that takes two sequences of events"s of length m and s of length n, each possibly containing an event more than once"and decides in time o(m + n) whether s is a subsequence of s.

Which of the following is true of operations within a spreadsheet program’s built-in functions? a. operations within parentheses, then multiplication and division, and then addition and subtraction are computed. b. operations within parentheses, then addition and subtraction, and then multiplication and division are computed. c. multiplication and division, then addition and subtraction, and then operations within parentheses are computed. d. addition and subtraction, then multiplication and division, and then operations within parentheses are computed

4. a1. vince owns a television repair shop that is insured undera commercial package policy. the policy includes thebuilding and personal property coverage form and thecauses-of-loss broad form. the declarations page indicatesthat coverage applies to both the building and the namedinsured's business property. explain whether or not thefollowing losses would be covered under his policy. a. a fire occurs on the premises, and the building isbadly damaged. b. a burglar steals some money and securities from anunlocked safe. c. a business computer is damaged by vandals whobreak into the shop after business hours. d. a tornado touches down near the store. several tel-evision sets of customers in the shop for repair aredamaged in the storm. til