Homework 6 - Introduction to Analysis - Fall 97

The problems are due on November 18. This is a group assignment. Turn in only one one solution per group.

Problem 1. Let tex2html_wrap_inline78 be a continuous function on tex2html_wrap_inline80 so that both

displaymath74

and

displaymath75

Show that f is uniformly continuous on tex2html_wrap_inline80 .

Problem 2. A set is called an tex2html_wrap_inline86 -set, if it is the countable union of closed sets.
a. Show that the interval [0,1) is an tex2html_wrap_inline86 -set.
b. Show that every tex2html_wrap_inline86 -set is the countable union of compact sets.

Problem 3. Use the previous problem to show that the continuous image of an tex2html_wrap_inline86 -set is again an tex2html_wrap_inline86 -set: Let tex2html_wrap_inline98 be continuous on F, and let F be an tex2html_wrap_inline86 -set. Then f(F) is an tex2html_wrap_inline86 -set.

Problem 4. Let tex2html_wrap_inline110 be a continuous function. Show that f has a fixed point, i.e., there is an tex2html_wrap_inline114 satisfying f(x)=x. Hint: Consider the function f(x)-x.

Problem 5. A function tex2html_wrap_inline120 has the intermediate value property, if for all tex2html_wrap_inline122 and all tex2html_wrap_inline124 there is an tex2html_wrap_inline126 satisfying f(x)=y.
Let tex2html_wrap_inline120 be a one-to-one function with the intermediate value property. Show that f is monotone and continuous.


Helmut Knaust
Fri Oct 31 12:26:18 MST 1997