Folks,

I have mentioned that in reading RtR I keep stopping in an attempt to
learn something about yet one more branch of mathematics. ;-) I have
a bunch of Dover and Schaum's publications that have been useful.

One area that justs twists my noodle is topology and Penrose rather
expects that his readers have more than a passing knowledge of this topic.

I am currently reading "From Geometry to Topology" by Flegg, (Amazon
link:
http://www.amazon.com/Geometry-Topology-H-Graham-Flegg/dp/0486419614/ref=pd_bbs_\
sr_1/102-5822354-0916166?ie=UTF8&s=books&qid=1189260630&sr=8-1)

It is both interesting and thought provoking. Further, his purpose is
to make that link between the two topics in consideration of the fact
that we are all familiar with geometry. It is an inexpensive Dover book.

Thomas