1/2 a^{c0,a3}_{c2,a0} b^{c1,c2}_{a1,a2} c^{v0}_{a4} eta1^{a4}_{a3} a+(a0) a+(a1) a+(a2) a-(v0) a-(c1) a-(c0)
-a^{c0,a3}_{c2,a0} b^{c1,c2}_{a1,a4} c^{v0}_{a2} eta1^{a4}_{a3} a+(a0) a+(a1) a+(a2) a-(v0) a-(c1) a-(c0)