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author | Preston Pan <preston@nullring.xyz> | 2024-03-14 12:00:32 -0700 |
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committer | Preston Pan <preston@nullring.xyz> | 2024-03-14 12:00:32 -0700 |
commit | 7197cd031e6fe12a3efcc98a1ec0c3eb9c986e89 (patch) | |
tree | ce5171b05557c462dfaf4a5e30f71c053b711f49 /mindmap/limit.org | |
parent | 6131810bb69bcb7b221cb332391cd3482920b22b (diff) |
add stuff
Diffstat (limited to 'mindmap/limit.org')
-rw-r--r-- | mindmap/limit.org | 22 |
1 files changed, 16 insertions, 6 deletions
diff --git a/mindmap/limit.org b/mindmap/limit.org index 946e4d2..65ae15f 100644 --- a/mindmap/limit.org +++ b/mindmap/limit.org @@ -28,21 +28,31 @@ ordering: \forall a \in \mathbb{R}, - \infty < a < +\infty \end{align*} defined. Note that we can define equivalence relations on these symbols, but algebra reamins undefined. +** Unbounded Sequences +Unbounded sequences can still limit to $+\infty$ or $-\infty$, although the limit does not exist +for many unbounded sequences. If a sequence is one of: +1. unbounded above +2. unbounded below +but not both, it is possible that such sequences limit to $\infty$. ** Limits on Monotone Sequences An increasing sequence is a sequence $\{s_{n}\}$ defined such that: \begin{align*} \forall n \in \mathbb{N}, \forall m \in \mathbb{N}, n \ge m \implies s_{n} \ge s_{m}. \end{align*} -and now we wish to prove that the limit of monotone sequences always exist. - -\begin{align*} -\lim s_{n} = s \iff \forall \epsilon > 0, \exists N, n > N \implies | s_{n} - s | < \epsilon \\ -\end{align*} #+begin_theorem -If I am bad, then you are too. +The limit of monotone sequences always exists. #+end_theorem #+begin_proof +We know: +\begin{align*} +\lim s_{n} = s \iff \forall \epsilon > 0, \exists N, n > N \implies | s_{n} - s | < \epsilon \\ +\end{align*} +and our sequence $\{s_{n}\}$ is monotone. If $\{s_{n}\}$ is increasing, we have: +\begin{align*} +s_{n + 1} \ge s_{n} +\end{align*} +for all n. #+end_proof |