__Def 7__ Suppose M is a point collection. The statement taht P is a boundary point of M means P is a point and R is a region containing P, then R contains a point of M and a point not in M.

__Prob 5__ No point of a region is a boundary point.

__Prob 6__ Every region has a boundary point.

__Prob 7__ If P is a limit point of the point set M must P belong to M?

1) S_{1} and S_{2} are subsets of numbers.

2)Â S_{1} and S_{2} have no number in common.

3) Each point in S_{1} is to the left of each point in S_{2}.

4)The union of S_{1} and S_{2} is the real numbers R.

5) Either S_{1} has a right most number or S_{2} has a left most number.

__Prob 8__ There is a positive number t such that t*t=3.

__Prob 9__ If M is a number collection and B is a number such that each number in M is less than B than there is a number L such that no number in M exceeds L and if a is a number less than L, than there is a number in M greater than a.

__Def 8__ The statement that t is a graph means G is a point collection.

__Def 9__ The statement that f is a function meeans f is a graph such that no two points of f has the same first number.