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In Junior High (7th grade) my new school district introduced it, and when I changed schools in 8th grade I was there for the introduction of it to the Long Beach School system. Only when I attended High School and moved on to Algebra and Geometry did I finally leave all that crap behind.
.But now, I have found a use for it.
Let the set "S" represent the area of Mid-town New York.
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Let the set "A" represent the area where the bums hang out (which will include the Port Authority, Bryant Park, etc.).
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Let the set "B" represent the hang out of late night hipsters - Hell's Kitchen, Chelsea, TriBeCa.
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In this case of the intersection of S/A/B would be noted as the shaded area (although they call it only the Intersection of A and B , limited by the Set S, but it is assumed to include S as well).
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That intersection is where we live. And, after a Saturday night of bums, parting and no rain - also is the boundary of the stinkiest part of New York.
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I walked the dog this morning and it smells like a urine soaked sewer out there!