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