16.-Linear-Algebra-by-Kenneth-Hoffman · Problem 5.3.12

Determinants

Mathematics — Linear Algebra · permutation-matrices

Problem

If σ\sigma is a permutation of degree nn and AA is an n×nn \times n matrix over the field FF with row vectors α1,…,αn\alpha_1, \ldots, \alpha_n, let σ(A)\sigma(A) denote the n×nn \times n matrix with row vectors ασ1,…,ασn\alpha_{\sigma 1}, \ldots, \alpha_{\sigma n}. ((a)) Prove that σ(AB)=σ(A)B\sigma(AB) = \sigma(A)B, and in particular that σ(A)=σ(I)A\sigma(A) = \sigma(I)A. ((b)) If TT is the linear operator of Exercise 9, prove that the matrix of TT in the standard ordered basis is σ(I)\sigma(I). ((c)) Is σ−1(I)\sigma^{-1}(I) the inverse matrix of σ(I)\sigma(I)? ((d)) Is it true that σ(A)\sigma(A) is similar to AA?

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