Kramers--Wannier intertwiner
= Kramers--Wannier intertwiner
{c}
For a one-dimensional periodic <spin> chain, a <Kramers--Wannier intertwiner> maps vertex <spins> in the $X$ basis to edge <domain walls>. It obeys $D(X_iX_{i+1})=\widetilde Z_{i+1/2}D$ and $DZ_i=(\widetilde X_{i-1/2}\widetilde X_{i+1/2})D$ and identifies <spin configurations> related by the global $\mathbb Z_2$ symmetry.