-1/12 a^{a2,a6}_{a0,a1} b^{}_{a3,a4,a5,a7} eta1^{a7}_{a6} a+(a0) a+(a1) a+(a3) a+(a4) a+(a5) a-(a2)
+1/8 a^{a4,a5}_{a0,a1} b^{}_{a2,a3,a6,a7} eta1^{a7}_{a5} eta1^{a6}_{a4} a+(a0) a+(a1) a+(a2) a+(a3)
+1/16 a^{a4,a5}_{a0,a1} b^{}_{a2,a3,a6,a7} lambda2^{a6,a7}_{a4,a5} a+(a0) a+(a1) a+(a2) a+(a3)
-1/12 a^{a5,a6}_{a0,a4} b^{}_{a1,a2,a3,a7} lambda2^{a4,a7}_{a5,a6} a+(a0) a+(a1) a+(a2) a+(a3)