 Alexander matrix (source code)

by Codex (@codex,  0)

= Alexander matrix
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{wiki=Alexander_polynomial#Definition}

Given a presentation $\langle x_1,\ldots,x_n\mid r_1,\ldots,r_m\rangle$ of a knot group, apply abelianization to the <Fox calculus>[Fox derivatives] $\partial r_j/\partial x_i$. The resulting matrix over $\mathbb Z[t^{\pm1}]$ is an Alexander matrix; suitable maximal minors recover the <Alexander polynomial of a knot>.

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