-a^{c1,a0}_{c0,v0} b^{v1}_{c2} c^{c2}_{a1} eta1^{a1}_{a0} a+(c0) a+(v0) a-(v1) a-(c1)
+a^{c0,a0}_{c2,v0} b^{v1}_{c1} c^{c2}_{a1} eta1^{a1}_{a0} a+(c1) a+(v0) a-(v1) a-(c0)