Nice group structure on the elementary orbit space of unimodular rows

(1) If $R$ is an affine algebra of dimension $d\geq 4$ over $\overline{\mathbb{F}}_{p}$ with $p>3$, then the group structure on ${\rm Um}_d(R)/{\rm E}_d(R)$ nice. (2) a commutative noetherian ring 2$ such that E}_{d+1}(R)$ acts transitively Um}_{d+1}(R),$ Um}_{d+1}(R[X])/{\rm E}_{d+1}(R[X])$