1/4 a^{a2}_{c0,a0,a1} b^{c1,c2}_{a3} eta1^{a3}_{a2} a+(c0) a+(a0) a+(a1) a-(c2) a-(c1)
-1/2 a^{a2}_{c1,a0,a1} b^{c0,c1}_{a3} a+(a0) a+(a1) a+(a3) a-(a2) a-(c0)
+1/2 a^{a2}_{c1,a0,a1} b^{c0,c1}_{a3} eta1^{a3}_{a2} a+(a0) a+(a1) a-(c0)