-1/2 a^{a0}_{c0} b^{c0}_{a2} c^{a1,a3}_{v0,v1} gamma1^{a2}_{a3} a+(v0) a+(v1) a-(a1) a-(a0)
+1/4 a^{a2}_{c0} b^{c0}_{a3} c^{a0,a1}_{v0,v1} eta1^{a3}_{a2} a+(v0) a+(v1) a-(a1) a-(a0)