Set s of identities between relators
(xa) a-1,
(yb) b-1,
(xyc) c-1,
(xy6a-1) (xy6xc) (xy5a-1) (xy5xc) (xy4a-1) (xy4xc) (xy3a-1) (xy3xc) (xy2a-1) (xy2xc) (xya-1) (xyxc) c b-1 (y7a-1) (y6a-1) (y6xc) (y5a-1) (y5xc) (y4a-1) (y4xc) (y3a-1) (y3xc) (y2a-1) (y2xc) (ya-1) (yxc) a-1 (xc) (xb-1)