## Land and Tamme’s new result on the K-theory of pullbacks

Or: just what is a Milnor square? A Milnor square is a certain pullback in the category of associative rings. It happens when we have a ring $R$, a two-sided ideal $I\subseteq R$ and a ring homomorphism $f:R\to S$ such that the restriction $f:I\to f(I)$ is an isomorphism of rings without identity. Since $I$ is […]