Let Bn=⟨ρ0,ρ1,…,ρn−1⟩ subject to the relations that (ρiρj)mi,j=id with mi,i=1, mi,j=2 for |i−j|≥2, mi,i+1=3 for 0≤i<n−1 and finally mn−1,n=4. What are the normal subgroups of Bn and where might I find a reference? Computationally, I see that for all n>4 there are 9 of them and I would like to find some source which describes them explicitly.

**Answer**

**Attribution***Source : Link , Question Author : Rob Nicolaides , Answer Author : Community*