a^{a0}_{v0} b^{v2}_{a2} c^{a1,a3}_{v1,v2} gamma1^{a2}_{a3} a+(v0) a+(v1) a-(a1) a-(a0)
-1/2 a^{a2}_{v0} b^{v2}_{a3} c^{a0,a1}_{v1,v2} eta1^{a3}_{a2} a+(v0) a+(v1) a-(a1) a-(a0)