Introduced the notion of a Cauchy sequence and then stated the theorem which says that all Cauchy sequences converge.
Using this theorem on Cauchy sequences we saw that the function
f:[0,1] ---> unit trianglular region
defined last time is indeed well-defined.
We observed that f is continuous (at least in the sense that nearby points get sent to nearby points).
In preparation for the proof that f is surjective we introduced the notion of a closed subset A in a topological space X. We also introduced the notion of a accummulation point of a subset A.
Ended by stating the theorem: a subset A is closed if and only if it contains all of its accumulation points. We'll prove this next lecture.