Witt group of a field
= Witt group of a field
{c}
{title2=$W(K)$}
For a field $K$ of characteristic different from two, $W(K)$ is the group of nonsingular symmetric bilinear forms modulo metabolic forms, with orthogonal sum as addition. A metabolic form has a half-dimensional totally isotropic subspace. Such a form is equivalent to a sum of hyperbolic planes, hence represents zero.