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