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8 votes
1 answer
1k views

Is there an efficient algorithm to check whether two matrices are the same up to row and column permutations?

Define $\mathcal M_n$ as the set of all $n\times n$ matrices with each entry either 1 or $x$. Two such matrices are equivalent iff they can be obtained from each other by swapping pairs of rows and ...
Wolfgang's user avatar
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6 votes
1 answer
500 views

Rank and frequency of permutations

(a) Let $[n] = \{1,\dotsc,n\}$, and let $\pi:[n]\to [n]$ be a permutation. Define an $n$-by-$n$ matrix $A=A(\pi)$ as follows: $A_{i,j}=1$ if $j>i$ and $\pi(j)>\pi(i)$, $A_{i,j}=-1$ If $j<i$ ...
H A Helfgott's user avatar
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3 votes
2 answers
316 views

Relation graph isomorphism to discrete logarithm

$\DeclareMathOperator\ora{ora}$Let $A_0$ be the adjacency matrix of graph $G$ and $P_0$ permutation matrix of multiplicative order $\rho$. Let $X$ be positive integer and $B_0=P_0^X A_0 P_0^{-X}$. Q1 ...
joro's user avatar
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