a^{c0,a2}_{c3,a0} b^{c1}_{v0} c^{c2,c3}_{a1,a3} eta1^{a3}_{a2} a+(a0) a+(a1) a+(v0) a-(c2) a-(c1) a-(c0)
+1/2 a^{c0,a2}_{c3,a0} b^{c3}_{v0} c^{c1,c2}_{a1,a3} eta1^{a3}_{a2} a+(a0) a+(a1) a+(v0) a-(c2) a-(c1) a-(c0)