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Midterm 1: Review
In the first part of this course, we covered the construction of real number, and some results about limit. Here is a list of key concepts
The numbers $\N, \Z, \Q$.
The axioms of field, an example of finite field $\F_5$.
The order relation, and ordered set. upper bound, lower bound. The least upper bound property.
$\R$ as equivalence classes of Cauchy sequences in $\Q$. Prove many familiar operations and properties of $\R$.
$\R$ has least upper bound property. (hence $\sup$ and $\inf$ of bounded subset in $\R$ exists in $\R$)
Sequences in $\R$, notion of convergence
Monotone bounded sequences are convergent (for increasing sequence, the $\lim a_n = \sup\{a_n: n \in \N \}$; for decreasing one, $\lim a_n = \inf \{a_n: n \in \N\}$.
lim-sup and lim-inf. The “epsilon of room” philosophy.
Thm: Cauchy sequences are convergent.
Limit Points, 3 equivalent definitions
Sample Problems