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