RS-3: customer surveys

A user maintains information on all of her customers, at the bare
minimum their names:

myCust:john, myCust:hasName, "Johnny Pesky"
myCust:aaron, myCust:hasName, "Aaron Boone"
myCust:bill, myCust:hasName, "Bill Buckner"

Customers are encouraged to fill in surveys with questions about their
interests. Among the questions asked is "Will you be purchasing a
lawnmower in the next twelve months?" Not all customers answered the
question:

myCust:john, myCust:willBuyMower, "false"^^xsd:boolean
myCust:aaron, myCust:willBuyMower, "true"^^xsd:boolean

(note that additional data is available for myCust::bill)

RS-3a:

The user wishes to find the names of all customers who plan on buying a
mower.

RS-3b:

The user wishes to find the names of all customers who do not plan on
buying a mower.

RS-3c:

The user wishes to find the names of all customers who *might* plan on
buying a mower. Saying "no" on the survey disqualifies people from this
group.