Affine Metric Geometry and Weak Orthogonal Groups

By following the ideas underpinning the well-established ``homogeneous model'' of an $n$-dimensional Euclidean space, we investigate whether the motion group or the weak motion group of an $n$-dimensional affine metric space on a vector space $V$ over an arbitrary field admits a specific faithful linear representation as weak orthogonal group of an $(n+1)$-dimensional metric vector space. Apart from a few exceptions, such a representation exists precisely when the metric structure on $V$ is given by a quadratic form with a non-degenerate polar form.