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Specific Exclusions
So far we have found items that belong in Atlanta,
Georgia and fall in the categories of hotels, motels
or bread & breakfasts. But wait! Our boss just
reminded us that we're on a budget! We have to find
a place to stay that costs no more than $75/night.
How can we refine our search to find allowable places?
We could use another AND, but a different way to do
it would be to use "NOT." In this case, we
could use "NOT (Price > 75)." Note that
this is another spot where the language of Boolean
logic is different from the English language. In English,
we would say we need rooms where "the price is
not greater than $75." But the language of Boolean
logic considers "Price > $75" as one term
yielding "true" or "false," then
uses "NOT" to reverse that result.
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Quick Quiz
How would you write the Boolean expression
to describe the items in the area we
have found?
One answer is here.
Notice that this particular Venn diagram
gives us a set of areas on our diagram
that are disjoint. This is just a result
of the way the shapes were drawn. As we
said above, the shapes we use don't really
matter. What matters is that the diagram
helps us see the overlaps and exclusions
of our search areas. The search engine
will return a list of hits, and it will
not show non-contiguous areas. But there
are always other ways to draw it that would
give us a simpler view - in this case,
one contiguous area rather than disjoint
areas.
What simple change could you make
to the way this diagram is drawn that
makes the desired pages contiguous, and
the diagram is easier to understand?
One answer is here.
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