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9 votes
2 answers
794 views

Why do these finite group Dedekind matrices seem to have integer spectrum when specialized to the order of group elements?

Let $p$ be a prime and let $f_p$ be the permutation on the set $\{1,2,\cdots,p-1\}$ which is given by taking inverses in $\mathbb{Z}/(p)$: $$x \bmod(p) \mapsto \frac{1}{x} \bmod (p)$$ So for instance, ...
8 votes
1 answer
533 views

What is the minimum $k$ such that $A^k \equiv I$ mod p for invertible matrices?

Let $F$ be a finite field of order $p$, where $p$ is prime. For any $n\times n$ matrix $A$ that is invertible over $F$, then there would appear to exist integers $k$ such that $A^{k} = I$. My question ...