Arf invariant

The theorem also applies to (18.7) once one shows ker(D) is connected, it follows that a nondegenerate quadratic form of even rank over a finite field is determined by its discriminant or Arf invariant. 

Algebraic affine group scheme 24 Algebraic matrix group 29 Anisotropic torus 56 Anti-equivalence 15 Antipode 8 Arf invariant 147 Artin-Schreier theory 143 Augmentation ideal 13 Automorphism group scheme 58... 

The quadratic construction is an equivariant chain level generalization of the functional Steenrod square method used by Browder 5) to define the quadratic function needed to define the Arf invariant of a normal map of even-dimensional geometric Poincare complexes. 

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