-1/2 a^{c0,a1}_{c3,a0} b^{c1,c2}_{a2,v0} c^{c3}_{v1} eta1^{a2}_{a1} a+(a0) a+(v0) a+(v1) a-(c2) a-(c1) a-(c0)
+a^{c0,a1}_{c3,a0} b^{c1,c3}_{a2,v0} c^{c2}_{v1} eta1^{a2}_{a1} a+(a0) a+(v0) a+(v1) a-(c2) a-(c1) a-(c0)