-1/4 a^{c0,c1,a0,a3}_{} b^{}_{c2,a1,a2,a4} eta1^{a4}_{a3} a+(c2) a+(a1) a+(a2) a-(a0) a-(c1) a-(c0)
+1/4 a^{c0,c1,a1,a2}_{} b^{}_{c2,a0,a3,a4} eta1^{a4}_{a2} eta1^{a3}_{a1} a+(c2) a+(a0) a-(c1) a-(c0)
+1/8 a^{c0,c1,a1,a2}_{} b^{}_{c2,a0,a3,a4} lambda2^{a3,a4}_{a1,a2} a+(c2) a+(a0) a-(c1) a-(c0)