1/2 a^{v2}_{a0} b^{c0,v0}_{a1,v2} c^{a2,v1}_{c1,c2} gamma1^{a1}_{a2} a+(c1) a+(c2) a+(a0) a-(v1) a-(v0) a-(c0)
-1/2 a^{v2}_{a1} b^{c0,v0}_{a0,v2} c^{a2,v1}_{c1,c2} gamma1^{a1}_{a2} a+(c1) a+(c2) a+(a0) a-(v1) a-(v0) a-(c0)