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