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You$$re helping to organize a class on campus that has decided to give all of its students

wireless laptops for the semester. Thus, there is a collection of n wireless laptops; there

is also a collection of n wireless access points, to which a laptop can connect when it

is in range.

The laptops are currently scattered across campus; laptop l is within range of a set Sl

of access points. We will assume that each laptop is within range of at least one access

point $($so the sets Sl are nonempty$)$; we will also assume that every access point p has

at least one laptop within range of it$.$

To make sure that all the wireless connectivity software is working correctly, you need

to try having laptops make contact with access points in such a way that each laptop

and each access point is involved in at least one connection. Thus we will say that a

test set T is a collection of ordered pairs of the form $($l$,$ p$)$ for a laptop l and access

point p$,$ with the properties that