What are GT-shadows?

Vasily A. Dolgushev, Khanh Q. Le, Aidan A. Lorenz

Let $B_4$ (resp. $P{B}_4$) be the braid group (resp. the pure braid group) on 4 strands and $NF{I}_{P{B}_4}(B_4)$ be the poset whose objects are finite index normal subgroups of $B_4$ th…