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Topic: set builder notation
Replies: 12   Last Post: Aug 24, 2013 1:38 AM

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lite.on.beta@gmail.com

Posts: 134
Registered: 2/21/06
Re: set builder notation
Posted: Aug 24, 2013 1:38 AM
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On Saturday, August 17, 2013 7:34:26 AM UTC-4, graham...@gmail.com wrote:
> On Saturday, August 17, 2013 4:12:34 AM UTC-7, lite.o...@gmail.com wrote:
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> > S = {x /in A | P(x) }
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> > For the set builder notation above, what we really means is:
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> > all things x, such that "x is element of A *and* P(x) is true" correct?
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> > The vertical bar is essentially conjunction, correct?/
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> No, consider
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> S = { x /in A | P(a,b,x,y,z) }
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> there is an implicit ALL(x)
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> by placing x on the left of the bar.
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> x is no longer free in P
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> the conjunction A&B
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> just returns a value of true or false.
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But I said "for all x, x /in A and P(x)"
Which is Ax(x e A ^ P(x) )

So x is not free here? (Sorry if I misunderstood you)





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