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