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