Chapter 3 Flashcards
A set O c R is open if…
for all points a in O, there exists an ε-neighborhood Vε(a) c O
for all points a in O, there exists an ε-neighborhood Vε(a) c O
A set O c R is open if…
Theorem-
i. ) The union of an arbitrary collection of open sets is…
ii. ) The intersection of a finite collection of open sets…
i. ) … is open
ii. ) is open.
A point is a limit point of a set A if…
every ε-neighborhood Vε(x) of x intersects the set A at some point other than x.
every ε-neighborhood Vε(x) of x intersects the set A at some point other than x.
A point is a limit point of a set A if…
Theorem- A point x is a limit point of a set iff…
x = lim an for some sequence (an) contained in A satisfying an not equal to x for all n in N.
x = lim an for some sequence (an) contained in A satisfying an not equal to x for all n in N.
Theorem- A point x is a limit point of a set iff…
A point a in A is an isolated point of A if…
it is not a limit a point of A.
it is not a limit a point of A.
A point a in A is an isolated point of A if…
A set F c R is closed if…
F contains all its limit points.
F contains all its limit points.
A set F c R is closed if…
Theorem- A set F c R is closed if and only if…
every Cauchy sequence contained in F has a limit that is also an element of F.
every Cauchy sequence contained in F has a limit that is also an element of F.
Theorem- A set F c R is closed if and only if…
Density of Q in R- for every y in R, …
there exists a sequence of rational numbers that converges to y.
there exists a sequence of rational numbers that converges to y.
Density of Q in R- for every y in R, …