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