1/4 a^{v0,v1}_{c0,a0} b^{a1}_{c3} c^{c3,v2}_{c1,c2} gamma1^{a0}_{a1} a+(c0) a+(c1) a+(c2) a-(v2) a-(v1) a-(v0)
-1/4 a^{v0,v1}_{c3,a0} b^{a1}_{c0} c^{c3,v2}_{c1,c2} gamma1^{a0}_{a1} a+(c0) a+(c1) a+(c2) a-(v2) a-(v1) a-(v0)