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