//(p^4 + p^2)/2 algebras
<a,b,c|ca-baa,cb-ybaaa,pa-zbaaa,pb-tbaaa,pc-baa-bab-xbaaa,class=4>(all y,z,t, x ne 0, x~-x)
<a,b,c|ca-baa,cb-ybaaa,pa-zbaaa,pb-tbaaa,pc-baa-bab,class=4>(all y,z,t, [z,t]~[t,z])
