1/2 a^{a0,a1,a2}_{} b^{v1}_{a3,a4,v0} eta1^{a4}_{a2} eta1^{a3}_{a1} a+(v0) a-(v1) a-(a0)
+1/4 a^{a0,a1,a2}_{} b^{v1}_{a3,a4,v0} lambda2^{a3,a4}_{a1,a2} a+(v0) a-(v1) a-(a0)
-1/2 a^{a0,a1,a3}_{} b^{v1}_{a2,a4,v0} eta1^{a4}_{a3} a+(a2) a+(v0) a-(v1) a-(a1) a-(a0)