Determinants and Multilinear Forms

Stub. The determinant built two ways — inductively via cofactor expansion, and axiomatically as the alternating n-linear form on the columns/rows — plus bilinear and quadratic forms, and tensor products of vector spaces.

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Two routes to the same object. The computational route (Friedberg–Insel– Spence): determinants of order 2, then order nn by cofactor expansion, their properties (multiplicativity, effect of row operations), and a summary characterization. The structural route (Axler): first build general bilinear/quadratic forms and general alternating multilinear forms, then show the determinant is the alternating nn-linear form on Fn\mathbf{F}^n normalized at the identity — which is also the natural setting to introduce tensor products of vector spaces.

Outline (TODO — flesh out each)

  • Determinants of order 2, and of order nn (cofactor expansion)
  • Properties of determinants; summary of important facts
  • A characterization of the determinant
  • Bilinear forms and symmetric bilinear forms; quadratic forms
  • Alternating multilinear forms and permutations
  • Defining and constructing the determinant as an alternating form
  • Tensor products — of two vector spaces, of inner product spaces, of multiple vector spaces

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