Typo fixes
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@ -57,14 +57,14 @@ In other words, show that there is always an integer $n$ so that $f^n(x) = x$.
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\vfill
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\definition{Composition}
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\definition{Composition}<compdef>
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The \textit{composition} of two permutations $f$ and $g$ is the permutation $h(x) = f(g(x))$. \par
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The usual notation for this is $f \circ g$, but we'll simply write $fg$.
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\problem{}
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What is $[1324][4321]$? \par
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How about $[321][213][231]$? \par
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\hint{composition is left-associative, so we evaluate $abc$ as $(ab)c$}
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\hint{is composition is left or right-associative? See \ref{compdef}}
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\vfill
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@ -440,7 +440,7 @@ How about $(123)$? And $(4231)$? \par
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\problem{}
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Say $\sigma$ is a permutation composed of cycles $\sigma_1\sigma_2...\sigma_k$. \par
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Say $\sigma$ is a permutation composed of disjoint cycles $\sigma_1\sigma_2...\sigma_k$. \par
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Say we know the order of all $\sigma_i$. What is the order of $\sigma$?
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\begin{solution}
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@ -479,7 +479,8 @@ Show that any permutation is a product of transpositions.
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Show that any permutation is a product of transpositions of the form $(1, k)$. \par
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\begin{solution}
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Use \ref{simpletrans} and rewrite each $(a, b)$ as $(1, a)(1, b)(1, a)$.
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Use \ref{simpletrans} and rewrite each $(a, b)$ as $(1, a)(1, b)(1, a)$. \par
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Showing that $(a, b) = (1, a)(1, b)(1, a)$ is fairly easy.
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\end{solution}
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\vfill
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@ -491,7 +492,8 @@ Show that any permutation is a product of transpositions of the form $(1, k)$. \
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Show that any transposition $(a, b)$ is equal to the product $(a, a+1)(a+1, b)(a, a+1)$.
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\begin{solution}
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TODO
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This is the same as the $(1, a)(1, b)(1, a)$ case above, but we use $a + 1$
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as a \say{working slot} instead of $1$.
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\end{solution}
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\vfill
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@ -98,7 +98,7 @@ Show that $\mathbb{Z}_7^\times$ and $\mathbb{Z}_9^\times$ are isomorphic.
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\problem{}
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Show that $\mathbb{Z}_{10}^\times$ and $\mathbb{Z}_4^\times$, and $\mathbb{Z}_3$ are isomorphic.
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Show that $\mathbb{Z}_{10}^\times$ and $\mathbb{Z}_5^\times$, and $\mathbb{Z}_4$ are isomorphic.
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\hint{
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Build a bijection with the above properties. \\
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Remember that a group is fully defined by its multiplication table.
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