-1/4 a^{a1,a2}_{c1,a0} b^{c0}_{c2} c^{c1,c2}_{v0,v1} a+(a0) a+(v0) a+(v1) a-(a2) a-(a1) a-(c0)
+1/4 a^{a1,a2}_{c1,a0} b^{c1}_{c2} c^{c0,c2}_{v0,v1} a+(a0) a+(v0) a+(v1) a-(a2) a-(a1) a-(c0)