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