diff --git a/blueprint/src/content.tex b/blueprint/src/content.tex index 005e922..49b2bca 100644 --- a/blueprint/src/content.tex +++ b/blueprint/src/content.tex @@ -382,8 +382,48 @@ \section{Holder's Theorem} $|q_g(n_1+n_2) - q_g(n_1) - q_g(n_2)| \le 1$. The third step:\\ \\ -We define a map that takes each element $g \in G$ to the real number which is the limit -of the sequence $\frac{q_g(n)}{n}$. We then check that this map is a group homomorphism. +We define a map $\phi$ that takes each element $g \in G$ to the real number which is the limit +of the sequence $\frac{q_g(n)}{n}$. + +We then check that this map is a group homomorphism. +Let $g_1,g_2 \in G$. Our goal is to show that $\phi(g_1) + \phi(g_2) = \phi(g_1g_2)$. +We know that for any $p \in \mathbb{N}$, there exists $q_1$ and $q_2$ such that +\[ +f^{q_1} \le g_1^p < f^{q_1 + 1} +\] +and +\[ +f^{q_2} \le g_2^p < f^{q_2 + 1} +\] + +We now do case work based on whether $g_1g_2 \le g_2g_1$ or +$g_2g_1 \le g_1g_2$. Let's look at the first case. +Then we have that $g_1^pg_2p \le (g_1g_2)^p \le g_2^pg_1^p$. +Furthermore we have that $f^{q_1+q_2} \le g_1^pg_2^p$ and that +$g_2^pg_1^p < f^{q_1+q_2+2}$. Therefore, +\[ +f^{q_1+q_2} \le g_1^pg_2^p \le (g_1g_2)^p \le g_2^pg_1^p < f^{q_1+q_2+2} +\] +Therefore, for each $p$ +\[ +q_1+q_2 \le q_{g_1g_2}(p) \le q_1+q_2 + 1 +\] +And so +\[ +\lim_{p \to\infty} \frac{q_1+q_2}{p} \le \lim_{p\to\infty} \frac{q_{g_1g_2}(p)}{p}=\phi(g_1g_2) \le \lim_{p\to\infty} \frac{q_1+q_2 + 1}{p} +\] + +Now we have that +\begin{align*} +\phi(g_1) + \phi(g_2) &= \lim_{p\to \infty} \frac{q_1}{p} + \lim_{p\to\infty} \frac{q_2}{p}\\ +&= \lim_{p\to\infty} \frac{q_1+q_2}{p}\\ +&\le \phi(g_1g_2)\\ +&\le \lim_{p\to\infty} \frac{q_1+q_2 + 1}{p} +&= \lim_{p\to\infty} \frac{q_1+q_2}{p}\\ +&= \phi(g_1)+\phi(g_2) +\end{align*} +Thus, $\phi(g_1g_2) = \phi(g_1) + \phi(g_2)$. +And the other case is the same. The fourth step:\\ \\ We check that the map is injective and order-preserving.