
Re: set builder notation
Posted:
Aug 24, 2013 1:38 AM


On Saturday, August 17, 2013 7:34:26 AM UTC4, graham...@gmail.com wrote: > On Saturday, August 17, 2013 4:12:34 AM UTC7, lite.o...@gmail.com wrote: > > > S = {x /in A  P(x) } > > > > > > > > > > > > For the set builder notation above, what we really means is: > > > > > > > > > > > > all things x, such that "x is element of A *and* P(x) is true" correct? > > > > > > > > > > > > The vertical bar is essentially conjunction, correct?/ > > > > > > > > No, consider > > > > S = { x /in A  P(a,b,x,y,z) } > > > > > > > > > > there is an implicit ALL(x) > > by placing x on the left of the bar. > > > > > > x is no longer free in P > > > > > > the conjunction A&B > > just returns a value of true or false. > >
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)

