Combinatorial descriptions of biclosed sets in affine type

Grant T. Barkley, David E Speyer

Let $W$ be a Coxeter group and let ${\Phi }^{+}$ be its positive roots. A subset $B$ of ${\Phi }^{+}$ is called biclosed if, whenever we have roots $\alpha$, $\beta$ and $\gamma$ with $γ\in \mathbb{R}_{>0} α+ \…