-1/2 a^{a0,a1}_{c2,v0} b^{c0,c2}_{a2,v1} c^{a3}_{c1} gamma1^{a2}_{a3} a+(c1) a+(v0) a+(v1) a-(a1) a-(a0) a-(c0)
-a^{a0,a2}_{c2,v0} b^{c0,c2}_{a3,v1} c^{a1}_{c1} eta1^{a3}_{a2} a+(c1) a+(v0) a+(v1) a-(a1) a-(a0) a-(c0)