Abstract:
We prove that the tangent space to the $(n+1)$th Milnor $K$-group of a ring $R$ is isomorphic to the group of $n$th absolute Kähler differentials of $R$ when the ring $R$ contains $1/2$ and has sufficiently many invertible elements. More precisely, the latter condition means that $R$ is weakly $5$-fold stable in the sense of Morrow.