Seifert-matrix presentation of the Alexander module
ID: seifert-matrix-presentation-of-the-alexander-module
Cut a knot exterior along a Seifert surface and stack copies to form its infinite cyclic cover. Linking-dual generators for the homology of the cut-open piece give the positive and negative inclusion matrices and in row convention. The gluing relations therefore have matrix . The H0 gluing map is multiplication by and is injective, so these relations present the entire Alexander module of a knot. Its order is the determinant, up to a Laurent unit.
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