Client/server awareness. visit three local stores in your neighborhood or mall and notice the information technology in the store – e. g., computerized cash registers, surveillance cameras, inventory information, etc. ask an employee about the technology. if the store uses servers, report what they do and what the clients do. questions should be polite and specific. do employees need special training to use the computers? are servers kept in the back of the store? is there a computer somewhere else linked to computers in the store? do they ever break down? what happens if they do break down? write a report of about five hundred words describing the information in the stores, and submit it to the teacher.

The idea that, for each pair of devices v and w, there’s a strict dichotomy between being “in range” or “out of range” is a simplified abstraction. more accurately, there’s a power decay function f (·) that specifies, for a pair of devices at distance δ, the signal strength f(δ) that they’ll be able to achieve on their wireless connection. (we’ll assume that f (δ) decreases with increasing δ.) we might want to build this into our notion of back-up sets as follows: among the k devices in the back-up set of v, there should be at least one that can be reached with very high signal strength, at least one other that can be reached with moderately high signal strength, and so forth. more concretely, we have values p1 ≥ p2 ≥ . . ≥ pk, so that if the back-up set for v consists of devices at distances d1≤d2≤≤dk, thenweshouldhavef(dj)≥pj foreachj. give an algorithm that determines whether it is possible to choose a back-up set for each device subject to this more detailed condition, still requiring that no device should appear in the back-up set of more than b other devices. again, the algorithm should output the back-up sets themselves, provided they can be found.\